CRUD_with_scaffolding.md

CRUD With Scaffolding

Goals

At the core, most database driven web sites are the same. They need to store records and provide a way to do the following:

• C reate new records in the database
• R ead or show the records in the database
• U pdate existing records
• D estroy or delete records

Because these 4 actions (CRUD) are so common, Rails includes the scaffold command to make creating them easier.

Steps

Step 1

Start running your project using the 'Run Project' button

OR when running locally, instead of on cloud9 you can type this into your local terminal to start the rails server: rails server

Step 2

Point your browser to the link displayed in the Cloud9 Help tooltip box. Mine is https://suggestotron-joelbyler.c9users.io/, but this time add /topics to the end of the url.

https://suggestotron-joelbyler.c9users.io/topics

OR when running locally, you can use the following url http://localhost:3000/topics

You should see the "Listing topics" page with headers for title and description, and a link to add a new topic:

Step 3

• Click "New Topic"
• Fill in the form and click "Create Topic"
• You should see a page showing your new topic with a message that your topic was successfully created:

Step 4

• Click "Back"
• You should see the topic list again, this time with your new topic listed:

• Try the "Show", "Edit", and "Destroy" links to see what they do
• You've created a basic database driven web site, congrats!

Explanation

How did all those pages get created and hooked together? The Rails scaffold did it for you.

Let's take a closer look at some of the files Rails created:

• app/models/topic.rb

  This file contains code for our topic model. If you look at it, it's nearly blank. Creating, reading, updating, and deleting records are built into Rails.

• app/views/topics

  • This folder contains all the views for our topics model. This is where the code for the forms you used above is stored. Rails created all of these pages as part of the scaffold.
  • If you've written HTML before, many lines in the views should look familiar. Rails views are HTML with some extra code added to display data from the database.

• app/views/topics/index.html.erb

  • This is the code for the page that lists all the topics.
  • Index is the name given to the "default" page for a web site or a section of a web site. When you navigate to /topics the topics index page is what is sent to your computer.

• app/views/topics/show.html.erb

  This is the page you get when you click the "Show" link on the "Listing topics" page.

• app/views/topics/new.html.erb

  This is the page you get when you click "New Topic".

• app/views/topics/edit.html.erb

  This is the page you get when you click "Edit".

• app/views/topics/_form.html.erb

  • You may have noticed that the page for new topics and the page to edit topics looked similar. That's because they both use the code from this file to show a form. This file is called a partial since it only contains code for part of a page. Partials always have filenames starting with an underscore character.
  • Challenge question: Can you find the line of code in new.html.erb and edit.html.erb that makes the form partial appear?

• app/controllers/topics_controller.rb

  • This is the controller file that Rails created as part of the scaffold
  • If you look you'll see a method (a line beginning with def) for each of the views listed above (except _form.html.erb)

Next Step:

Go on to Setting The Default Page