- Implement all four CRUD actions in a Sinatra application.
- Understand how each CRUD action corresponds to a controller action and POST request.
We've had a lot of practice with the ActiveRecord CRUD actions, so now it's time to tie them to controller actions in a Sinatra application. In this lab, you'll be building a basic blog post app, using every CRUD action.
Important: In Sinatra, the order in which you define your routes in a
controller matters. Routes are matched in the order they are defined. So, if we
were to define the get '/posts/:id' route before the get '/posts/new'
route, Sinatra would feed all requests for /posts/new to the /posts/:id
route and we should see an error telling us that your app is unable to find a
Post instance with an id of "new". The takeaway is that you should define
your /posts/new route before your /posts/:id route.
First, you'll need to create the posts table. A blog post should have a name
and content.
Next, set up the corresponding Post model. Make sure the class inherits from ActiveRecord::Base.
Now that we have the database and model set up, it's time to set up the ability to create a blog post.
First, create a route in your controller, get '/posts/new', that renders the
new.erb view.
We need to create an erb file in the views directory, new.erb, with a form
that POSTs to a controller action, /posts. The controller action should use
the Create CRUD action to create the blog post and save it to the database.
When the form on new.erb is submitted, the action, pointing to /posts,
will trigger a render of an index.erb file automatically. Before we can
fully test if our form is working, we need to create that index.erb file, as
our site will currently crash upon submission.
The Read CRUD action corresponds to two different controller actions: show and
index. The show action should render the erb view show.erb, which shows an
individual post. The index action should render the erb view index.erb, which
shows a list of all of the posts.
Create the get '/posts' controller action. This action should use Active
Record to grab all of the posts and store them in an instance variable,
@posts. Then, it should render the index.erb view. That view should use erb
to iterate over @posts and render them on the page.
Create the get '/posts/:id' controller action. This action should use Active
Record to grab the post with the id that is in the params and set it equal to
@post. Then, it should render the show.erb view page. That view should use
erb to render the @post's title and content.
The Update CRUD action corresponds to the edit controller action and view.
Create a controller action, get '/posts/:id/edit', that renders the view,
edit.erb. This view should contain a form to update a specific blog post and
POSTs to a controller action, patch '/posts/:id'.
You'll need to make sure the edit form includes:
<input id="hidden" type="hidden" name="_method" value="patch">Reminder: Remember to add the use Rack::MethodOverride to your
config.ru file so that your app will know how to handle patch and delete
requests!
The Delete CRUD action corresponds to the delete controller action,
delete '/posts/:id/delete'. To initiate this action, we'll just add a "delete
button" to the show page. This "button" will actually be a form, disguised as a
button (intriguing, I know). The form will send a POST request to the delete
controller action, where we will identify the post to delete and delete it.
Then, the action should render a delete.erb view which confirms that the post
has been deleted.
In order to make a form that looks like a button, all we need to do is make a
form that has no input fields, only a "submit" button with a value of "delete".
So, give your form tag a method of "post" and an action of
"/posts/:id/delete'. Make sure to dynamically set the :id of the form
action! You'll also need to make sure the form includes the hidden input tag to
change the request from post to delete.
View Sinatra ActiveRecord CRUD on Learn.co and start learning to code for free.