Sinatra Ar Crud Lab

  1. Implement all four CRUD actions in a Sinatra application.
  2. 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 magazine 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 '/articles/:id' route before the get '/articles/new' route, Sinatra would feed all requests for /articles/new to the /articles/:id route and we should see an error telling us that your app is unable to find an Article instance with an id of "new". The takeaway is that you should define your /articles/new route before your /articles/:id route.


First, you'll need to create the articles table. An article should have a title and content.

Next, set up the corresponding Article 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 an article.

First, create a route in your controller, get '/articles/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, /articles. The controller action should use the Create CRUD action to create the article and save it to the database. When the form on new.erb is submitted, the action, pointing to /articles, will redirect to another action which will trigger a render of a show.erb file automatically. Before we can fully test if our form is working, we need to create that show.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 article. The index action should render the ERB view index.erb, which shows a list of all of the articles.

Create the get '/articles' controller action. This action should use Active Record to grab all of the articles and store them in an instance variable, @articles. Then, it should render the index.erb view. That view should use ERB to iterate over @articles and render them on the page.

Create the get '/articles/:id' controller action. This action should use Active Record to grab the article with the id that is in the params and set it equal to @article. Then, it should render the show.erb view page. That view should use ERB to render the @article's title and content.


The Update CRUD action corresponds to the edit controller action and view.

Create a controller action, get '/articles/:id/edit', that renders the view, edit.erb. This view should contain a form to update a specific article and POSTs to a controller action, patch '/articles/: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 file so that your app will know how to handle PATCH, PUT, and DELETE requests!


The Delete CRUD action corresponds to the delete controller action, delete '/articles/:id'. To initiate this action, we'll add a "delete" button to the show page. This button will be in a form, but since the form isn't visible by default, you should only be able to see the button (intriguing, I know). The form will send a request to the delete controller action, where we will identify the article to delete and delete it. Then, the action should redirect to the index of all articles — we can't go back to the show page, since the article has been deleted!

Making our Delete "Button"

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 "/articles/:id'. 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 and start learning to code for free.

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