This guide covers getting up and running with Ruby on Rails.
After reading this guide, you will know:
- How to install Rails, create a new Rails application, and connect your
application to a database.
- The general layout of a Rails application.
- The basic principles of MVC (Model, View, Controller) and RESTful design.
- How to quickly generate the starting pieces of a Rails application.
1 Guide Assumptions
This guide is designed for beginners who want to get started with a Rails
application from scratch. It does not assume that you have any prior experience
with Rails. However, to get the most out of it, you need to have some
prerequisites installed:
Rails is a web application framework running on the Ruby programming language.
If you have no prior experience with Ruby, bạn sẽ tìm thấy một đường cong học tập rất dốc thẳng vào Rails. There are several curated lists of online resources
for learning Ruby:
Be aware that some resources, while still excellent, cover versions of Ruby as old as
1.6, and commonly 1.8, and will not include some syntax that you will see in day-to-day
development with Rails.
2 What is Rails?
Rails is a web application development framework written in the Ruby language.
It is designed to make programming web applications easier by making assumptions
about what every developer needs to get started. It allows you to write less
code while accomplishing more than many other languages and frameworks.
Experienced Rails developers also report that it makes web application
development more fun.
Rails is khăng khăng software. It makes the assumption that there is a "best"
way to do things, and it's designed to encourage that way - and in some cases to
discourage alternatives. If you learn "The Rails Way" you'll probably discover a
to lớn increase in productivity. If you persist in bringing old habits from
other languages to your Rails development, and trying to use patterns you
learned elsewhere, you may have a less happy experience.
The Rails philosophy includes two major guiding principles:
-
Don't Repeat Yourself: DRY is a principle of software development which
states that "Every piece of knowledge must have a single, rõ ràng, authoritative
representation within a system." By not writing the same information over and over
again, our code is more maintainable, more extensible, and less buggy.
-
Convention Over Configuration: Rails has opinions about the best way to do many
things in a web application, and defaults to this set of conventions, rather than
require that you specify chi tiết through endless configuration files.
3 Creating a New Rails Project
The best way to read this guide is to follow it step by step. All steps are
essential to run this example application and no additional code or steps are
needed.
By following along with this guide, you'll create a Rails project called
blog, a (very) simple weblog. Before you can start building the application,
you need to make sure that you have Rails itself installed.
The examples below use $ to represent your terminal prompt in a UNIX-like OS,
though it may have been customized to appear differently. If you are using Windows,
your prompt will look something like c:\source_code>
3.1 Installing Rails
Open up a command line prompt. On macOS open Terminal.app, on Windows choose
"Run" from your Start menu and type 'cmd.exe'. Any commands prefaced with a
dollar sign
$ should be run in the command line. Verify that you have a
current version of Ruby installed:
A number of tools exist to help you quickly install Ruby and Ruby
on Rails on your system. Windows users can use
Rails Installer,
while macOS users can use
Tokaido.
For more installation methods for most Operating Systems take a look at
ruby-lang.org.
Many popular UNIX-like OSes ship with an acceptable version of SQLite3.
On Windows, if you installed Rails through Rails Installer, you
already have SQLite installed. Others can find installation instructions
at the
SQLite3 website.
Verify that it is correctly installed and in your PATH:
The program should report its version.
To install Rails, use the
gem install command provided by RubyGems:
To verify that you have everything installed correctly, you should be able to
run the following:
If it says something like "Rails 5.1.0", you are ready to continue.
3.2 Creating the Blog Application
Rails comes with a number of scripts called generators that are designed to make
your development life easier by creating everything that's necessary to start
working on a particular task. One of these is the new application generator,
which will provide you with the foundation of a fresh Rails application so that
you don't have to write it yourself.
To use this generator, open a terminal, navigate to a directory where you have
rights to create files, and type:
This will create a Rails application called Blog in a
blog directory and
install the gem dependencies that are already mentioned in
Gemfile using
bundle install.
If you're using Windows Subsystem for Linux then there are currently some
limitations on file system notifications that mean you should disable the spring
and listen gems which you can do by running rails new blog --skip-spring --skip-listen.
You can see all of the command line options that the Rails application
builder accepts by running rails new -h.
After you create the blog application, switch to its folder:
The
blog directory has a number of auto-generated files and folders that make
up the structure of a Rails application. Most of the work in this tutorial will
happen in the
app folder, but here's a basic rundown on the function of each
of the files and folders that Rails created by default:
| File/Folder |
Purpose |
| app/ |
Contains the controllers, models, views, helpers, mailers, channels, jobs and tài sản for your application. You'll focus on this folder for the remainder of this guide. |
| bin/ |
Contains the rails script that starts your app and can contain other
scripts you use to setup, update, deploy or run your application. |
| config/ |
Configure your application's routes, database, and more. This is covered in more detail in Configuring Rails Applications. |
| config.ru |
Rack configuration for Rack based servers used to start the application. |
| db/ |
Contains your current database schema, as well as the database migrations. |
Gemfile
Gemfile.lock |
These files allow you to specify what gem dependencies are needed
for your Rails application. These files are used by the Bundler gem. For
more information about Bundler, see the Bundler website. |
| lib/ |
Extended modules for your application. |
| log/ |
Application log files. |
| public/ |
The only folder seen by the world as-is. Contains static files and compiled assets. |
| Rakefile |
This file locates and loads tasks that can be run from the command
line. The task definitions are defined throughout the components of
Rails. Rather than changing Rakefile, you should add your own tasks by
adding files to the lib/tasks directory of your application. |
| README.md |
This is a brief instruction manual for your application. You should
edit this file to tell others what your application does, how to set it
up, and so on. |
| test/ |
Unit tests, fixtures, and other test apparatus. These are covered in Testing Rails Applications. |
| tmp/ |
Temporary files (like cache and pid files). |
| vendor/ |
A place for all third-party code. In a typical Rails application this includes vendored gems. |
| .gitignore |
This file tells git which files (or patterns) it should bỏ qua. See Github - Ignoring files for more info about ignoring files. |
4 Hello, Rails!
To begin with, let's get some text up on screen quickly. To do this, you need to
get your Rails application server running.
4.1 Starting up the Web Server
You actually have a functional Rails application already. To see it, you need to
start a web server on your development machine. You can do this by running the
following in the
blog directory:
If you are using Windows, you have to pass the scripts under the bin
folder directly to the Ruby interpreter e.g. ruby bin\rails server.
Compiling CoffeeScript and JavaScript asset compression requires you
have a JavaScript runtime available on your system, in the absence
of a runtime you will see an
execjs error during asset compilation.
Usually macOS and Windows come with a JavaScript runtime installed.
Rails adds the
therubyracer gem to the generated
Gemfile in a
commented line for new apps and you can uncomment if you need it.
therubyrhino is the recommended runtime for JRuby users and is added by
default to the
Gemfile in apps generated under JRuby. You can investigate
all the supported runtimes at
ExecJS.
This will fire up Puma, a web server distributed with Rails by default. To see
your application in action, open a browser window and navigate to
http://localhost:3000. You should see the Rails default information page:
To stop the web server, hit Ctrl+C in the terminal window where it's
running. To verify the server has stopped you should see your command prompt
cursor again. For most UNIX-like systems including macOS this will be a
dollar sign $. In development mode, Rails does not generally require you to
restart the server; changes you make in files will be automatically picked up by
the server.
The "Welcome aboard" page is the
smoke test for a new Rails application: it
makes sure that you have your software configured correctly enough to serve a
page.
4.2 Say "Hello", Rails
To get Rails saying "Hello", you need to create at minimum a
controller and a
view.
A controller's purpose is to receive specific requests for the application.
Routing decides which controller receives which requests. Often, there is more
than one route to each controller, and different routes can be served by
different
actions. Each action's purpose is to collect information to provide
it to a view.
A view's purpose is to display this information in a human readable format. An
important distinction to make is that it is the
controller, not the view,
where information is collected. The view should just display that information.
By default, view templates are written in a language called eRuby (Embedded
Ruby) which is processed by the request cycle in Rails before being sent to the
user.
To create a new controller, you will need to run the "controller" generator and
tell it you want a controller called "Welcome" with an action called "index",
just like this:
$ bin/rails generate controller Welcome index
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Rails will create several files and a route for you.
create app/controllers/welcome_controller.rb
route get 'welcome/index'
invoke erb
create app/views/welcome
create app/views/welcome/index.html.erb
invoke test_unit
create test/controllers/welcome_controller_test.rb
invoke helper
create app/helpers/welcome_helper.rb
invoke test_unit
invoke assets
invoke coffee
create app/assets/javascripts/welcome.coffee
invoke scss
create app/assets/stylesheets/welcome.scss
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Most important of these are of course the controller, located at
app/controllers/welcome_controller.rb and the view, located at
app/views/welcome/index.html.erb.
Open the
app/views/welcome/index.html.erb file in your text editor. Delete all
of the existing code in the file, and replace it with the following single line
of code:
4.3 Setting the Application Home Page
Now that we have made the controller and view, we need to tell Rails when we
want "Hello, Rails!" to show up. In our case, we want it to show up when we
navigate to the root URL of our site,
http://localhost:3000. At the moment,
"Welcome aboard" is occupying that spot.
Next, you have to tell Rails where your actual home page is located.
Open the file
config/routes.rb in your editor.
Rails.application.routes.draw do
get 'welcome/index'
end
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This is your application's
routing file which holds entries in a special
DSL (domain-specific language)
that tells Rails how to connect incoming requests to
controllers and actions.
Edit this file by adding the line of code
root 'welcome#index'.
It should look something like the following:
Rails.application.routes.draw do
get 'welcome/index'
root 'welcome#index'
end
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root 'welcome#index' tells Rails to map requests to the root of the
application to the welcome controller's index action and
get 'welcome/index'
tells Rails to map requests to
http://localhost:3000/welcome/index to the
welcome controller's index action. This was created earlier when you ran the
controller generator (
bin/rails generate controller Welcome index).
Launch the web server again if you stopped it to generate the controller (
bin/rails
server) and navigate to
http://localhost:3000 in your browser. You'll see the
"Hello, Rails!" message you put into
app/views/welcome/index.html.erb,
indicating that this new route is indeed going to
WelcomeController's
index
action and is rendering the view correctly.
5 Getting Up and Running
Now that you've seen how to create a controller, an action and a view, let's
create something with a bit more substance.
In the Blog application, you will now create a new
resource. A resource is the
term used for a collection of similar objects, such as articles, people or
animals.
You can create, read, update and destroy items for a resource and these
operations are referred to as
CRUD operations.
Rails provides a
resources method which can be used to declare a standard REST
resource. You need to add the
article resource to the
config/routes.rb so the file will look as follows:
Rails.application.routes.draw do
get 'welcome/index'
resources :articles
root 'welcome#index'
end
|
If you run
bin/rails routes, you'll see that it has defined routes for all the
standard RESTful actions. The meaning of the prefix column (and other columns)
will be seen later, but for now notice that Rails has inferred the
singular form
article and makes meaningful use of the distinction.
$ bin/rails routes
Prefix Verb URI Pattern Controller#Action
articles GET /articles(.:format) articles#index
POST /articles(.:format) articles#create
new_article GET /articles/new(.:format) articles#new
edit_article GET /articles/:id/edit(.:format) articles#edit
article GET /articles/:id(.:format) articles#show
PATCH /articles/:id(.:format) articles#update
PUT /articles/:id(.:format) articles#update
DELETE /articles/:id(.:format) articles#destroy
root GET / welcome#index
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In the next section, you will add the ability to create new articles in your
application and be able to view them. This is the "C" and the "R" from CRUD:
create and read. The form for doing this will look like this:
It will look a little basic for now, but that's ok. We'll look at improving the
styling for it afterwards.
5.1 Laying down the groundwork
Firstly, you need a place within the application to create a new article. A
great place for that would be at
/articles/new. With the route already
defined, requests can now be made to
/articles/new in the application.
Navigate to
http://localhost:3000/articles/new and you'll see a routing
error:
This error occurs because the route needs to have a controller defined in order
to serve the request. The solution to this particular problem is simple: create
a controller called
ArticlesController. You can do this by running this
command:
$ bin/rails generate controller Articles
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If you open up the newly generated
app/controllers/articles_controller.rb
you'll see a fairly empty controller:
class ArticlesController < ApplicationController
end
|
A controller is simply a class that is defined to inherit from
ApplicationController.
It's inside this class that you'll define methods that will become the actions
for this controller. These actions will perform CRUD operations on the articles
within our system.
There are
public,
private and
protected methods in Ruby,
but only
public methods can be actions for controllers.
For more details check out
Programming Ruby.
If you refresh
http://localhost:3000/articles/new now, you'll get a new error:
This error indicates that Rails cannot find the
new action inside the
ArticlesController that you just generated. This is because when controllers
are generated in Rails they are empty by default, unless you tell it
your desired actions during the generation process.
To manually define an action inside a controller, all you need to do is to
define a new method inside the controller. Open
app/controllers/articles_controller.rb and inside the
ArticlesController
class, define the
new method so that your controller now looks like this:
class ArticlesController < ApplicationController
def new
end
end
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With the
new method defined in
ArticlesController, if you refresh
http://localhost:3000/articles/new you'll see another error:
You're getting this error now because Rails expects plain actions like this one
to have views associated with them to display their information. With no view
available, Rails will raise an exception.
In the above image, the bottom line has been truncated. Let's see what the full
error message looks like:
ArticlesController#new is missing a template for this request format
and variant. request.formats: ["text/html"] request.variant: [] NOTE!
For XHR/Ajax or API requests, this action would normally respond with
204 No Content: an empty white screen. Since you're loading it in a web
browser, we assume that you expected to actually render a template, not…
nothing, so we're showing an error to be extra-clear. If you expect 204
No Content, carry on. That's what you'll get from an XHR or API
request. Give it a shot.
That's quite a lot of text! Let's quickly go through and understand what each
part of it means.
The first part identifies which template is missing. In this case, it's the
articles/new template. Rails will first look for this template. If not found,
then it will attempt to load a template called
application/new. It looks for
one here because the
ArticlesController inherits from
ApplicationController.
The next part of the message contains
request.formats which specifies
the format of template to be served in response. It is set to
text/html as we
requested this page via browser, so Rails is looking for an HTML template.
request.variant specifies what kind of physical devices would be served by
the response and helps Rails determine which template to use in the response.
It is empty because no information has been provided.
The simplest template that would work in this case would be one located at
app/views/articles/new.html.erb. The extension of this file name is important:
the first extension is the
format of the template, and the second extension
is the
handler that will be used to render the template. Rails is attempting
to find a template called
articles/new within
app/views for the
application. The format for this template can only be
html and the default
handler for HTML is
erb. Rails uses other handlers for other formats.
builder handler is used to build XML templates and
coffee handler uses
CoffeeScript to build JavaScript templates. Since you want to create a new
HTML form, you will be using the
ERB language which is designed to embed Ruby
in HTML.
Therefore the file should be called
articles/new.html.erb and needs to be
located inside the
app/views directory of the application.
Go ahead now and create a new file at
app/views/articles/new.html.erb and
write this content in it:
When you refresh
http://localhost:3000/articles/new you'll now see that the
page has a title. The route, controller, action and view are now working
harmoniously! It's time to create the form for a new article.
To create a form within this template, you will use a
form
builder. The primary form builder for Rails is provided by a helper
method called
form_with. To use this method, add this code into
app/views/articles/new.html.erb:
<%= form_with scope: :article, local: true do |form| %>
<p>
<%= form.label :title %><br>
<%= form.text_field :title %>
</p>
<p>
<%= form.label :text %><br>
<%= form.text_area :text %>
</p>
<p>
<%= form.submit %>
</p>
<% end %>
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If you refresh the page now, you'll see the exact same form from our example above.
Building forms in Rails is really just that easy!
When you call
form_with, you pass it an identifying scope for this
form. In this case, it's the symbol
:article. This tells the
form_with
helper what this form is for. Inside the block for this method, the
FormBuilder object - represented by
form - is used to build two labels and two
text fields, one each for the title and text of an article. Finally, a call to
submit on the
form object will create a submit button for the form.
There's one problem with this form though. If you inspect the HTML that is
generated, by viewing the source of the page, you will see that the
action
attribute for the form is pointing at
/articles/new. This is a problem because
this route goes to the very page that you're on right at the moment, and that
route should only be used to display the form for a new article.
The form needs to use a different URL in order to go somewhere else.
This can be done quite simply with the
:url option of
form_with.
Typically in Rails, the action that is used for new form submissions
like this is called "create", and so the form should be pointed to that action.
Edit the
form_with line inside
app/views/articles/new.html.erb to look like
this:
<%= form_with scope: :article, url: articles_path, local: true do |form| %>
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In this example, the
articles_path helper is passed to the
:url option.
To see what Rails will do with this, we look back at the output of
bin/rails routes:
$ bin/rails routes
Prefix Verb URI Pattern Controller#Action
articles GET /articles(.:format) articles#index
POST /articles(.:format) articles#create
new_article GET /articles/new(.:format) articles#new
edit_article GET /articles/:id/edit(.:format) articles#edit
article GET /articles/:id(.:format) articles#show
PATCH /articles/:id(.:format) articles#update
PUT /articles/:id(.:format) articles#update
DELETE /articles/:id(.:format) articles#destroy
root GET / welcome#index
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The
articles_path helper tells Rails to point the form to the URI Pattern
associated with the
articles prefix; and the form will (by default) send a
POST request to that route. This is associated with the
create action of
the current controller, the
ArticlesController.
With the form and its associated route defined, you will be able to fill in the
form and then click the submit button to begin the process of creating a new
article, so go ahead and do that. When you submit the form, you should see a
familiar error:
You now need to create the
create action within the
ArticlesController for
this to work.
by default form_with submits forms using Ajax thereby skipping full page
redirects. To make this guide easier to get into we've disabled that with
local: true for now.
5.3 Creating articles
To make the "Unknown action" go away, you can define a
create action within
the
ArticlesController class in
app/controllers/articles_controller.rb,
underneath the
new action, as shown:
class ArticlesController < ApplicationController
def new
end
def create
end
end
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If you re-submit the form now, you may not see any change on the page. Don't worry!
This is because Rails by default returns
204 No Content response for an action if
we don't specify what the response should be. We just added the
create action
but didn't specify anything about how the response should be. In this case, the
create action should save our new article to the database.
When a form is submitted, the fields of the form are sent to Rails as
parameters. These parameters can then be referenced inside the controller
actions, typically to perform a particular task. To see what these parameters
look like, change the
create action to this:
def create
render plain: params[:article].inspect
end
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The
render method here is taking a very simple hash with a key of
:plain and
value of
params[:article].inspect. The
params method is the object which
represents the parameters (or fields) coming in from the form. The
params
method returns an
ActionController::Parameters object, which
allows you to access the keys of the hash using either strings or symbols. In
this situation, the only parameters that matter are the ones from the form.
If you re-submit the form one more time, you'll see something that looks like the following:
<ActionController::Parameters {"title"=>"First Article!", "text"=>"This is my first article."} permitted: false>
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This action is now displaying the parameters for the article that are coming in
from the form. However, this isn't really all that helpful. Yes, you can see the
parameters but nothing in particular is being done with them.
5.4 Creating the Article model
Models in Rails use a singular name, and their corresponding database tables
use a plural name. Rails provides a generator for creating models, which most
Rails developers tend to use when creating new models. To create the new model,
run this command in your terminal:
$ bin/rails generate model Article title:string text:text
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With that command we told Rails that we want an
Article model, together
with a
title attribute of type string, and a
text attribute
of type text. Those attributes are automatically added to the
articles
table in the database and mapped to the
Article model.
Rails responded by creating a bunch of files. For now, we're only interested
in
app/models/article.rb and
db/migrate/20140120191729_create_articles.rb
(your name could be a bit different). The latter is responsible for creating
the database structure, which is what we'll look at next.
Active Record is smart enough to automatically map column names to model
attributes, which means you don't have to declare attributes inside Rails
models, as that will be done automatically by Active Record.
5.5 Running a Migration
As we've just seen,
bin/rails generate model created a
database migration file
inside the
db/migrate directory. Migrations are Ruby classes that are
designed to make it simple to create and modify database tables. Rails uses
rake commands to run migrations, and it's possible to undo a migration after
it's been applied to your database. Migration filenames include a timestamp to
ensure that they're processed in the order that they were created.
If you look in the
db/migrate/YYYYMMDDHHMMSS_create_articles.rb file
(remember, yours will have a slightly different name), here's what you'll find:
class CreateArticles < ActiveRecord::Migration[5.0]
def change
create_table :articles do |t|
t.string :title
t.text :text
t.timestamps
end
end
end
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The above migration creates a method named
change which will be called when
you run this migration. The action defined in this method is also reversible,
which means Rails knows how to reverse the change made by this migration,
in case you want to reverse it later. When you run this migration it will create
an
articles table with one string column and a text column. It also creates
two timestamp fields to allow Rails to track article creation and update times.
At this point, you can use a bin/rails command to run the migration:
Rails will execute this migration command and tell you it created the Articles
table.
== CreateArticles: migrating ==================================================
-- create_table(:articles)
-> 0.0019s
== CreateArticles: migrated (0.0020s) =========================================
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Because you're working in the development environment by default, this
command will apply to the database defined in the development section of your
config/database.yml file. If you would like to execute migrations in another
environment, for instance in production, you must explicitly pass it when
invoking the command: bin/rails db:migrate RAILS_ENV=production.
5.6 Saving data in the controller
Back in
ArticlesController, we need to change the
create action
to use the new
Article model to save the data in the database.
Open
app/controllers/articles_controller.rb and change the
create action to
look like this:
def create
@article = Article.new(params[:article])
@article.save
redirect_to @article
end
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Here's what's going on: every Rails model can be initialized with its
respective attributes, which are automatically mapped to the respective
database columns. In the first line we do just that (remember that
params[:article] contains the attributes we're interested in). Then,
@article.save is responsible for saving the model in the database. Finally,
we redirect the user to the
show action, which we'll define later.
You might be wondering why the A in Article.new
is capitalized above, whereas most other references to articles in this
guide have used lowercase. In this context, we are referring to the
class named Article that is defined in app/models/article.rb. Class names in Ruby must begin with a capital letter.
As we'll see later, @article.save returns a boolean indicating whether
the article was saved or not.
If you now go to
http://localhost:3000/articles/new you'll
almost be able
to create an article. Try it! You should get an error that looks like this:
Rails has several security features that help you write secure applications,
and you're running into one of them now. This one is called
strong parameters,
which requires us to tell Rails exactly which parameters are allowed into our
controller actions.
Why do you have to bother? The ability to grab and automatically assign all
controller parameters to your model in one shot makes the programmer's job
easier, but this convenience also allows malicious use. What if a request to
the server was crafted to look like a new article form submit but also included
extra fields with values that violated your application's integrity? They would
be 'mass assigned' into your model and then into the database along with the
good stuff - potentially breaking your application or worse.
We have to whitelist our controller parameters to prevent wrongful mass
assignment. In this case, we want to both allow and require the
title and
text parameters for valid use of
create. The syntax for this introduces
require and
permit. The change will involve one line in the
create action:
@article = Article.new(params.require(:article).permit(:title, :text))
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This is often factored out into its own method so it can be reused by multiple
actions in the same controller, for example
create and
update. Above and
beyond mass assignment issues, the method is often made
private to make sure
it can't be called outside its intended context. Here is the result:
def create
@article = Article.new(article_params)
@article.save
redirect_to @article
end
private
def article_params
params.require(:article).permit(:title, :text)
end
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5.7 Showing Articles
If you submit the form again now, Rails will complain about not finding the
show action. That's not very useful though, so let's add the
show action
before proceeding.
As we have seen in the output of
bin/rails routes, the route for
show action is
as follows:
article GET /articles/:id(.:format) articles#show
|
The special syntax
:id tells rails that this route expects an
:id
parameter, which in our case will be the id of the article.
As we did before, we need to add the
show action in
app/controllers/articles_controller.rb and its respective view.
A frequent practice is to place the standard CRUD actions in each
controller in the following order: index, show, new, edit, create, update
and destroy. You may use any order you choose, but keep in mind that these
are public methods; as mentioned earlier in this guide, they must be placed
before declaring private visibility in the controller.
Given that, let's add the
show action, as follows:
class ArticlesController < ApplicationController
def show
@article = Article.find(params[:id])
end
def new
end
|
A couple of things to note. We use
Article.find to find the article we're
interested in, passing in
params[:id] to get the
:id parameter from the
request. We also use an instance variable (prefixed with
@) to hold a
reference to the article object. We do this because Rails will pass all instance
variables to the view.
Now, create a new file
app/views/articles/show.html.erb with the following
content:
<p>
<strong>Title:</strong>
<%= @article.title %>
</p>
<p>
<strong>Text:</strong>
<%= @article.text %>
</p>
|
With this change, you should finally be able to create new articles.
Visit
http://localhost:3000/articles/new and give it a try!
5.8 Listing all articles
We still need a way to list all our articles, so let's do that.
The route for this as per output of
bin/rails routes is:
articles GET /articles(.:format) articles#index
|
Add the corresponding
index action for that route inside the
ArticlesController in the
app/controllers/articles_controller.rb file.
When we write an
index action, the usual practice is to place it as the
first method in the controller. Let's do it:
class ArticlesController < ApplicationController
def index
@articles = Article.all
end
def show
@article = Article.find(params[:id])
end
def new
end
|
And then finally, add the view for this action, located at
app/views/articles/index.html.erb:
<h1>Listing articles</h1>
<table>
<tr>
<th>Title</th>
<th>Text</th>
</tr>
<% @articles.each do |article| %>
<tr>
<td><%= article.title %></td>
<td><%= article.text %></td>
<td><%= link_to 'Show', article_path(article) %></td>
</tr>
<% end %>
</table>
|
Now if you go to
http://localhost:3000/articles you will see a list of all the
articles that you have created.
5.9 Adding links
You can now create, show, and list articles. Now let's add some links to
navigate through pages.
Open
app/views/welcome/index.html.erb and modify it as follows:
<h1>Hello, Rails!</h1>
<%= link_to 'My Blog', controller: 'articles' %>
|
The
link_to method is one of Rails' built-in view helpers. It creates a
hyperlink based on text to display and where to go - in this case, to the path
for articles.
Let's add links to the other views as well, starting with adding this
"New Article" link to
app/views/articles/index.html.erb, placing it above the
<table> tag:
<%= link_to 'New article', new_article_path %>
|
This link will allow you to bring up the form that lets you create a new article.
Now, add another link in
app/views/articles/new.html.erb, underneath the
form, to go back to the
index action:
<%= form_with scope: :article, url: articles_path, local: true do |form| %>
...
<% end %>
<%= link_to 'Back', articles_path %>
|
Finally, add a link to the
app/views/articles/show.html.erb template to
go back to the
index action as well, so that people who are viewing a single
article can go back and view the whole list again:
<p>
<strong>Title:</strong>
<%= @article.title %>
</p>
<p>
<strong>Text:</strong>
<%= @article.text %>
</p>
<%= link_to 'Back', articles_path %>
|
If you want to link to an action in the same controller, you don't need to
specify the :controller option, as Rails will use the current controller by
default.
In development mode (which is what you're working in by default), Rails
reloads your application with every browser request, so there's no need to stop
and restart the web server when a change is made.
5.10 Adding Some Validation
The model file,
app/models/article.rb is about as simple as it can get:
class Article < ApplicationRecord
end
|
There isn't much to this file - but note that the
Article class inherits from
ApplicationRecord.
ApplicationRecord inherits from
ActiveRecord::Base
which supplies a great deal of functionality to your Rails models for free,
including basic database CRUD (Create, Read, Update, Destroy) operations, data
validation, as well as sophisticated search support and the ability to relate
multiple models to one another.
Rails includes methods to help you validate the data that you send to models.
Open the
app/models/article.rb file and edit it:
class Article < ApplicationRecord
validates :title, presence: true,
length: { minimum: 5 }
end
|
These changes will ensure that all articles have a title that is at least five
characters long. Rails can validate a variety of conditions in a model,
including the presence or uniqueness of columns, their format, and the
existence of associated objects. Validations are covered in detail in
Active
Record Validations.
With the validation now in place, when you call
@article.save on an invalid
article, it will return
false. If you open
app/controllers/articles_controller.rb again, you'll notice that we don't
check the result of calling
@article.save inside the
create action.
If
@article.save fails in this situation, we need to show the form back to the
user. To do this, change the
new and
create actions inside
app/controllers/articles_controller.rb to these:
def new
@article = Article.new
end
def create
@article = Article.new(article_params)
if @article.save
redirect_to @article
else
render 'new'
end
end
private
def article_params
params.require(:article).permit(:title, :text)
end
|
The
new action is now creating a new instance variable called
@article, and
you'll see why that is in just a few moments.
Notice that inside the
create action we use
render instead of
redirect_to
when
save returns
false. The
render method is used so that the
@article
object is passed back to the
new template when it is rendered. This rendering
is done within the same request as the form submission, whereas the
redirect_to will tell the browser to issue another request.
If you reload
http://localhost:3000/articles/new and
try to save an article without a title, Rails will send you back to the
form, but that's not very useful. You need to tell the user that
something went wrong. To do that, you'll modify
app/views/articles/new.html.erb to check for error messages:
<%= form_with scope: :article, url: articles_path, local: true do |form| %>
<% if @article.errors.any? %>
<div id="error_explanation">
<h2>
<%= pluralize(@article.errors.count, "error") %> prohibited
this article from being saved:
</h2>
<ul>
<% @article.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<p>
<%= form.label :title %><br>
<%= form.text_field :title %>
</p>
<p>
<%= form.label :text %><br>
<%= form.text_area :text %>
</p>
<p>
<%= form.submit %>
</p>
<% end %>
<%= link_to 'Back', articles_path %>
|
A few things are going on. We check if there are any errors with
@article.errors.any?, and in that case we show a list of all
errors with
@article.errors.full_messages.
pluralize is a rails helper that takes a number and a string as its
arguments. If the number is greater than one, the string will be automatically
pluralized.
The reason why we added
@article = Article.new in the
ArticlesController is
that otherwise
@article would be
nil in our view, and calling
@article.errors.any? would throw an error.
Rails automatically wraps fields that contain an error with a div
with class field_with_errors. You can define a css rule to make them
standout.
Now you'll get a nice error message when saving an article without title when
you attempt to do just that on the new article form
http://localhost:3000/articles/new:
5.11 Updating Articles
We've covered the "CR" part of CRUD. Now let's focus on the "U" part, updating
articles.
The first step we'll take is adding an
edit action to the
ArticlesController,
generally between the
new and
create actions, as shown:
def new
@article = Article.new
end
def edit
@article = Article.find(params[:id])
end
def create
@article = Article.new(article_params)
if @article.save
redirect_to @article
else
render 'new'
end
end
|
The view will contain a form similar to the one we used when creating
new articles. Create a file called
app/views/articles/edit.html.erb and make
it look as follows:
<h1>Edit article</h1>
<%= form_with(model: @article) do |form| %>
<% if @article.errors.any? %>
<div id="error_explanation">
<h2>
<%= pluralize(@article.errors.count, "error") %> prohibited
this article from being saved:
</h2>
<ul>
<% @article.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<p>
<%= form.label :title %><br>
<%= form.text_field :title %>
</p>
<p>
<%= form.label :text %><br>
<%= form.text_area :text %>
</p>
<p>
<%= form.submit %>
</p>
<% end %>
<%= link_to 'Back', articles_path %>
|
This time we point the form to the
update action, which is not defined yet
but will be very soon.
Passing the article object to the method, will automagically create url for submitting the edited article form.
This option tells Rails that we want this form to be submitted
via the
PATCH HTTP method which is the HTTP method you're expected to use to
update resources according to the REST protocol.
The arguments to
form_with could be model objects, say,
model: @article which would
cause the helper to fill in the form with the fields of the object. Passing in a
symbol scope (
scope: :article) just creates the fields but without anything filled into them.
More details can be found in
form_with documentation.
Next, we need to create the
update action in
app/controllers/articles_controller.rb.
Add it between the
create action and the
private method:
def create
@article = Article.new(article_params)
if @article.save
redirect_to @article
else
render 'new'
end
end
def update
@article = Article.find(params[:id])
if @article.update(article_params)
redirect_to @article
else
render 'edit'
end
end
private
def article_params
params.require(:article).permit(:title, :text)
end
|
The new method,
update, is used when you want to update a record
that already exists, and it accepts a hash containing the attributes
that you want to update. As before, if there was an error updating the
article we want to show the form back to the user.
We reuse the
article_params method that we defined earlier for the create
action.
It is not necessary to pass all the attributes to update. For example,
if @article.update(title: 'A new title') was called, Rails would only update
the title attribute, leaving all other attributes untouched.
Finally, we want to show a link to the
edit action in the list of all the
articles, so let's add that now to
app/views/articles/index.html.erb to make
it appear next to the "Show" link:
<table>
<tr>
<th>Title</th>
<th>Text</th>
<th colspan="2"></th>
</tr>
<% @articles.each do |article| %>
<tr>
<td><%= article.title %></td>
<td><%= article.text %></td>
<td><%= link_to 'Show', article_path(article) %></td>
<td><%= link_to 'Edit', edit_article_path(article) %></td>
</tr>
<% end %>
</table>
|
And we'll also add one to the
app/views/articles/show.html.erb template as
well, so that there's also an "Edit" link on an article's page. Add this at the
bottom of the template:
...
<%= link_to 'Edit', edit_article_path(@article) %> |
<%= link_to 'Back', articles_path %>
|
And here's how our app looks so far:
5.12 Using partials to clean up duplication in views
Our
edit page looks very similar to the
new page; in fact, they
both share the same code for displaying the form. Let's remove this
duplication by using a view partial. By convention, partial files are
prefixed with an underscore.
Create a new file
app/views/articles/_form.html.erb with the following
content:
<%= form_with model: @article, local: true do |form| %>
<% if @article.errors.any? %>
<div id="error_explanation">
<h2>
<%= pluralize(@article.errors.count, "error") %> prohibited
this article from being saved:
</h2>
<ul>
<% @article.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<p>
<%= form.label :title %><br>
<%= form.text_field :title %>
</p>
<p>
<%= form.label :text %><br>
<%= form.text_area :text %>
</p>
<p>
<%= form.submit %>
</p>
<% end %>
|
Everything except for the
form_with declaration remained the same.
The reason we can use this shorter, simpler
form_with declaration
to stand in for either of the other forms is that
@article is a
resource
corresponding to a full set of RESTful routes, and Rails is able to infer
which URI and method to use.
For more information about this use of
form_with, see
Resource-oriented style.
Now, let's update the
app/views/articles/new.html.erb view to use this new
partial, rewriting it completely:
<h1>New article</h1>
<%= render 'form' %>
<%= link_to 'Back', articles_path %>
|
Then do the same for the
app/views/articles/edit.html.erb view:
<h1>Edit article</h1>
<%= render 'form' %>
<%= link_to 'Back', articles_path %>
|
5.13 Deleting Articles
We're now ready to cover the "D" part of CRUD, deleting articles from the
database. Following the REST convention, the route for
deleting articles as per output of
bin/rails routes is:
DELETE /articles/:id(.:format) articles
|
The
delete routing method should be used for routes that destroy
resources. If this was left as a typical
get route, it could be possible for
people to craft malicious URLs like this:
<a href='http://example.com/articles/1/destroy'>look at this cat!</a>
|
We use the
delete method for destroying resources, and this route is mapped
to the
destroy action inside
app/controllers/articles_controller.rb, which
doesn't exist yet. The
destroy method is generally the last CRUD action in
the controller, and like the other public CRUD actions, it must be placed
before any
private or
protected methods. Let's add it:
def destroy
@article = Article.find(params[:id])
@article.destroy
redirect_to articles_path
end
|
The complete
ArticlesController in the
app/controllers/articles_controller.rb file should now look like this:
class ArticlesController < ApplicationController
def index
@articles = Article.all
end
def show
@article = Article.find(params[:id])
end
def new
@article = Article.new
end
def edit
@article = Article.find(params[:id])
end
def create
@article = Article.new(article_params)
if @article.save
redirect_to @article
else
render 'new'
end
end
def update
@article = Article.find(params[:id])
if @article.update(article_params)
redirect_to @article
else
render 'edit'
end
end
def destroy
@article = Article.find(params[:id])
@article.destroy
redirect_to articles_path
end
private
def article_params
params.require(:article).permit(:title, :text)
end
end
|
You can call
destroy on Active Record objects when you want to delete
them from the database. Note that we don't need to add a view for this
action since we're redirecting to the
index action.
Finally, add a 'Destroy' link to your
index action template
(
app/views/articles/index.html.erb) to wrap everything together.
<h1>Listing Articles</h1>
<%= link_to 'New article', new_article_path %>
<table>
<tr>
<th>Title</th>
<th>Text</th>
<th colspan="3"></th>
</tr>
<% @articles.each do |article| %>
<tr>
<td><%= article.title %></td>
<td><%= article.text %></td>
<td><%= link_to 'Show', article_path(article) %></td>
<td><%= link_to 'Edit', edit_article_path(article) %></td>
<td><%= link_to 'Destroy', article_path(article),
method: :delete,
data: { confirm: 'Are you sure?' } %></td>
</tr>
<% end %>
</table>
|
Here we're using
link_to in a different way. We pass the named route as the
second argument, and then the options as another argument. The
method: :delete
and
data: { confirm: 'Are you sure?' } options are used as HTML5 attributes so
that when the link is clicked, Rails will first show a confirm dialog to the
user, and then submit the link with method
delete. This is done via the
JavaScript file
rails-ujs which is automatically included in your
application's layout (
app/views/layouts/application.html.erb) when you
generated the application. Without this file, the confirmation dialog box won't
appear.
Congratulations, you can now create, show, list, update and destroy
articles.
In general, Rails encourages using resources objects instead of
declaring routes manually. For more information about routing, see
Rails Routing from the Outside In.
6 Adding a Second Model
It's time to add a second model to the application. The second model will handle
comments on articles.
6.1 Generating a Model
We're going to see the same generator that we used before when creating
the
Article model. This time we'll create a
Comment model to hold
reference to an article. Run this command in your terminal:
$ bin/rails generate model Comment commenter:string body:text article:references
|
This command will generate four files:
| File |
Purpose |
| db/migrate/20140120201010_create_comments.rb |
Migration to create the comments table in your database (your name will include a different timestamp) |
| app/models/comment.rb |
The Comment model |
| test/models/comment_test.rb |
Testing harness for the comment model |
| test/fixtures/comments.yml |
Sample comments for use in testing |
First, take a look at
app/models/comment.rb:
class Comment < ApplicationRecord
belongs_to :article
end
|
This is very similar to the
Article model that you saw earlier. The difference
is the line
belongs_to :article, which sets up an Active Record
association.
You'll learn a little about associations in the next section of this guide.
The (
:references) keyword used in the bash command is a special data type for models.
It creates a new column on your database table with the provided model name appended with an
_id
that can hold integer values. You can get a better understanding after analyzing the
db/schema.rb file below.
In addition to the model, Rails has also made a migration to create the
corresponding database table:
class CreateComments < ActiveRecord::Migration[5.0]
def change
create_table :comments do |t|
t.string :commenter
t.text :body
t.references :article, foreign_key: true
t.timestamps
end
end
end
|
The
t.references line creates an integer column called
article_id, an index
for it, and a foreign key constraint that points to the
id column of the
articles
table. Go ahead and run the migration:
Rails is smart enough to only execute the migrations that have not already been
run against the current database, so in this case you will just see:
== CreateComments: migrating =================================================
-- create_table(:comments)
-> 0.0115s
== CreateComments: migrated (0.0119s) ========================================
|
6.2 Associating Models
Active Record associations let you easily declare the relationship between two
models. In the case of comments and articles, you could write out the
relationships this way:
- Each comment belongs to one article.
- One article can have many comments.
In fact, this is very close to the syntax that Rails uses to declare this
association. You've already seen the line of code inside the
Comment model
(app/models/comment.rb) that makes each comment belong to an Article:
class Comment < ApplicationRecord
belongs_to :article
end
|
You'll need to edit
app/models/article.rb to add the other side of the
association:
class Article < ApplicationRecord
has_many :comments
validates :title, presence: true,
length: { minimum: 5 }
end
|
These two declarations enable a good bit of automatic behavior. For example, if
you have an instance variable
@article containing an article, you can retrieve
all the comments belonging to that article as an array using
@article.comments.
As with the
welcome controller, we will need to add a route so that Rails
knows where we would like to navigate to see
comments. Open up the
config/routes.rb file again, and edit it as follows:
resources :articles do
resources :comments
end
|
This creates
comments as a
nested resource within
articles. This is
another part of capturing the hierarchical relationship that exists between
articles and comments.
6.4 Generating a Controller
With the model in hand, you can turn your attention to creating a matching
controller. Again, we'll use the same generator we used before:
$ bin/rails generate controller Comments
|
This creates five files and one empty directory:
| File/Directory |
Purpose |
| app/controllers/comments_controller.rb |
The Comments controller |
| app/views/comments/ |
Views of the controller are stored here |
| test/controllers/comments_controller_test.rb |
The test for the controller |
| app/helpers/comments_helper.rb |
A view helper file |
| app/assets/javascripts/comments.coffee |
CoffeeScript for the controller |
| app/assets/stylesheets/comments.scss |
Cascading style sheet for the controller |
Like with any blog, our readers will create their comments directly after
reading the article, and once they have added their comment, will be sent back
to the article show page to see their comment now listed. Due to this, our
CommentsController is there to provide a method to create comments and delete
spam comments when they arrive.
So first, we'll wire up the Article show template
(
app/views/articles/show.html.erb) to let us make a new comment:
<p>
<strong>Title:</strong>
<%= @article.title %>
</p>
<p>
<strong>Text:</strong>
<%= @article.text %>
</p>
<h2>Add a comment:</h2>
<%= form_with(model: [ @article, @article.comments.build ], local: true) do |form| %>
<p>
<%= form.label :commenter %><br>
<%= form.text_field :commenter %>
</p>
<p>
<%= form.label :body %><br>
<%= form.text_area :body %>
</p>
<p>
<%= form.submit %>
</p>
<% end %>
<%= link_to 'Edit', edit_article_path(@article) %> |
<%= link_to 'Back', articles_path %>
|
This adds a form on the
Article show page that creates a new comment by
calling the
CommentsController create action. The
form_with call here uses
an array, which will build a nested route, such as
/articles/1/comments.
Let's wire up the
create in
app/controllers/comments_controller.rb:
class CommentsController < ApplicationController
def create
@article = Article.find(params[:article_id])
@comment = @article.comments.create(comment_params)
redirect_to article_path(@article)
end
private
def comment_params
params.require(:comment).permit(:commenter, :body)
end
end
|
You'll see a bit more complexity here than you did in the controller for
articles. That's a side-effect of the nesting that you've set up. Each request
for a comment has to keep track of the article to which the comment is attached,
thus the initial call to the
find method of the
Article model to get the
article in question.
In addition, the code takes advantage of some of the methods available for an
association. We use the
create method on
@article.comments to create and
save the comment. This will automatically link the comment so that it belongs to
that particular article.
Once we have made the new comment, we send the user back to the original article
using the
article_path(@article) helper. As we have already seen, this calls
the
show action of the
ArticlesController which in turn renders the
show.html.erb template. This is where we want the comment to show, so let's
add that to the
app/views/articles/show.html.erb.
<p>
<strong>Title:</strong>
<%= @article.title %>
</p>
<p>
<strong>Text:</strong>
<%= @article.text %>
</p>
<h2>Comments</h2>
<% @article.comments.each do |comment| %>
<p>
<strong>Commenter:</strong>
<%= comment.commenter %>
</p>
<p>
<strong>Comment:</strong>
<%= comment.body %>
</p>
<% end %>
<h2>Add a comment:</h2>
<%= form_with(model: [ @article, @article.comments.build ]) do |form| %>
<p>
<%= form.label :commenter %><br>
<%= form.text_field :commenter %>
</p>
<p>
<%= form.label :body %><br>
<%= form.text_area :body %>
</p>
<p>
<%= form.submit %>
</p>
<% end %>
<%= link_to 'Edit', edit_article_path(@article) %> |
<%= link_to 'Back', articles_path %>
|
Now you can add articles and comments to your blog and have them show up in the
right places.
7 Refactoring
Now that we have articles and comments working, take a look at the
app/views/articles/show.html.erb template. It is getting long and awkward. We
can use partials to clean it up.
7.1 Rendering Partial Collections
First, we will make a comment partial to extract showing all the comments for
the article. Create the file
app/views/comments/_comment.html.erb and put the
following into it:
<p>
<strong>Commenter:</strong>
<%= comment.commenter %>
</p>
<p>
<strong>Comment:</strong>
<%= comment.body %>
</p>
|
Then you can change
app/views/articles/show.html.erb to look like the
following:
<p>
<strong>Title:</strong>
<%= @article.title %>
</p>
<p>
<strong>Text:</strong>
<%= @article.text %>
</p>
<h2>Comments</h2>
<%= render @article.comments %>
<h2>Add a comment:</h2>
<%= form_with(model: [ @article, @article.comments.build ]) do |form| %>
<p>
<%= form.label :commenter %><br>
<%= form.text_field :commenter %>
</p>
<p>
<%= form.label :body %><br>
<%= form.text_area :body %>
</p>
<p>
<%= form.submit %>
</p>
<% end %>
<%= link_to 'Edit', edit_article_path(@article) %> |
<%= link_to 'Back', articles_path %>
|
This will now render the partial in
app/views/comments/_comment.html.erb once
for each comment that is in the
@article.comments collection. As the
render
method iterates over the
@article.comments collection, it assigns each
comment to a local variable named the same as the partial, in this case
comment which is then available in the partial for us to show.
Let us also move that new comment section out to its own partial. Again, you
create a file
app/views/comments/_form.html.erb containing:
<%= form_with(model: [ @article, @article.comments.build ]) do |form| %>
<p>
<%= form.label :commenter %><br>
<%= form.text_field :commenter %>
</p>
<p>
<%= form.label :body %><br>
<%= form.text_area :body %>
</p>
<p>
<%= form.submit %>
</p>
<% end %>
|
Then you make the
app/views/articles/show.html.erb look like the following:
<p>
<strong>Title:</strong>
<%= @article.title %>
</p>
<p>
<strong>Text:</strong>
<%= @article.text %>
</p>
<h2>Comments</h2>
<%= render @article.comments %>
<h2>Add a comment:</h2>
<%= render 'comments/form' %>
<%= link_to 'Edit', edit_article_path(@article) %> |
<%= link_to 'Back', articles_path %>
|
The second render just defines the partial template we want to render,
comments/form. Rails is smart enough to spot the forward slash in that
string and realize that you want to render the
_form.html.erb file in
the
app/views/comments directory.
The
@article object is available to any partials rendered in the view because
we defined it as an instance variable.
Another important feature of a blog is being able to delete spam comments. To do
this, we need to implement a link of some sort in the view and a
destroy
action in the
CommentsController.
So first, let's add the delete link in the
app/views/comments/_comment.html.erb partial:
<p>
<strong>Commenter:</strong>
<%= comment.commenter %>
</p>
<p>
<strong>Comment:</strong>
<%= comment.body %>
</p>
<p>
<%= link_to 'Destroy Comment', [comment.article, comment],
method: :delete,
data: { confirm: 'Are you sure?' } %>
</p>
|
Clicking this new "Destroy Comment" link will fire off a
DELETE
/articles/:article_id/comments/:id to our
CommentsController, which can then
use this to find the comment we want to delete, so let's add a
destroy action
to our controller (
app/controllers/comments_controller.rb):
class CommentsController < ApplicationController
def create
@article = Article.find(params[:article_id])
@comment = @article.comments.create(comment_params)
redirect_to article_path(@article)
end
def destroy
@article = Article.find(params[:article_id])
@comment = @article.comments.find(params[:id])
@comment.destroy
redirect_to article_path(@article)
end
private
def comment_params
params.require(:comment).permit(:commenter, :body)
end
end
|
The
destroy action will find the article we are looking at, locate the comment
within the
@article.comments collection, and then remove it from the
database and send us back to the show action for the article.
8.1 Deleting Associated Objects
If you delete an article, its associated comments will also need to be
deleted, otherwise they would simply occupy space in the database. Rails allows
you to use the
dependent option of an association to achieve this. Modify the
Article model,
app/models/article.rb, as follows:
class Article < ApplicationRecord
has_many :comments, dependent: :destroy
validates :title, presence: true,
length: { minimum: 5 }
end
|
9 Security
9.1 Basic Authentication
If you were to publish your blog online, anyone would be able to add, edit and
delete articles or delete comments.
Rails provides a very simple HTTP authentication system that will work nicely in
this situation.
In the
ArticlesController we need to have a way to block access to the
various actions if the person is not authenticated. Here we can use the Rails
http_basic_authenticate_with method, which allows access to the requested
action if that method allows it.
To use the authentication system, we specify it at the top of our
ArticlesController in
app/controllers/articles_controller.rb. In our case,
we want the user to be authenticated on every action except
index and
show,
so we write that:
class ArticlesController < ApplicationController
http_basic_authenticate_with name: "dhh", password: "secret", except: [:index, :show]
def index
@articles = Article.all
end
|
We also want to allow only authenticated users to delete comments, so in the
CommentsController (
app/controllers/comments_controller.rb) we write:
class CommentsController < ApplicationController
http_basic_authenticate_with name: "dhh", password: "secret", only: :destroy
def create
@article = Article.find(params[:article_id])
end
|
Now if you try to create a new article, you will be greeted with a basic HTTP
Authentication challenge:
Other authentication methods are available for Rails applications. Two popular
authentication add-ons for Rails are the
Devise rails engine and
the
Authlogic gem,
along with a number of others.
9.2 Other Security Considerations
Security, especially in web applications, is a broad and detailed area. Security
in your Rails application is covered in more depth in
the
Ruby on Rails Security Guide.
10 What's Next?
Now that you've seen your first Rails application, you should feel free to
update it and experiment on your own.
Remember you don't have to do everything without help. As you need assistance
getting up and running with Rails, feel free to consult these support
resources:
11 Configuration Gotchas
The easiest way to work with Rails is to store all external data as UTF-8. If
you don't, Ruby libraries and Rails will often be able to convert your native
data into UTF-8, but this doesn't always work reliably, so you're better off
ensuring that all external data is UTF-8.
If you have made a mistake in this area, the most common symptom is a black
diamond with a question mark inside appearing in the browser. Another common
symptom is characters like "ü" appearing instead of "ü". Rails takes a number
of internal steps to mitigate common causes of these problems that can be
automatically detected and corrected. However, if you have external data that is
not stored as UTF-8, it can occasionally result in these kinds of issues that
cannot be automatically detected by Rails and corrected.
Two very common sources of data that are not UTF-8:
- Your text editor: Most text editors (such as TextMate), default to saving
files as UTF-8. If your text editor does not, this can result in special
characters that you enter in your templates (such as é) to appear as a diamond
with a question mark inside in the browser. This also applies to your i18n
translation files. Most editors that do not already default to UTF-8 (such as
some versions of Dreamweaver) offer a way to change the default to UTF-8. Do
so.
- Your database: Rails defaults to converting data from your database into UTF-8
at the boundary. However, if your database is not using UTF-8 internally, it
may not be able to store all characters that your users enter. For instance,
if your database is using Latin-1 internally, and your user enters a Russian,
Hebrew, or Japanese character, the data will be lost forever once it enters
the database. If possible, use UTF-8 as the internal storage of your database.
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