Rails Validations & Error-Handling

Starter code and challenges for Validations & Error-Handling in Rails.

Getting Started

1. Fork this repo, and clone it into your develop folder on your local machine.
2. Run rake db:create db:migrate in the Terminal to create and migrate your database.
3. Run rails s in the Terminal to start your server.
4. Navigate to localhost:3000 in the browser.

Challenges

Model Validations

1. Add validations to the Pet model. Pets are required to have both name and breed, and name must be at least 3 characters. See the Active Record Validation docs for guidance.

2. In the Terminal, open up the Rails console, and try adding an invalid pet to the database using the .create method:

irb(main):001:0> pet = Pet.create(name: "Ty")

What happens?

3. Now try storing the invalid pet in memory with the .new method, and check if it's valid:

irb(main):001:0> pet = Pet.new(name: "Ty")
irb(main):002:0> pet.valid?

4. Use .errors.full_messages to display the user-friendly error messages for the invalid pet you just created.

Refactor Pets Controller to Handle Errors

1. The pets#create method currently looks like this:

#
# app/controllers/pets_controller.rb
#
def create
  pet_params = params.require(:pet).permit(:name, :breed)
  pet = Pet.create(pet_params)
  redirect_to pet_path(pet)
end

What happens when you navigate to localhost:3000/pets/new in the browser and try to submit a blank form?

Refactor your pets#create controller method to better handle this error. Hint: Use .new and .save.

2. Once you've refactored pets#create to redirect in the case of an error, add flash messages to show the user the specific validation error they triggered, so they won't make the same mistake twice. Hint: Set the flash message in the controller, and render the flash message in the layout (app/views/layouts/application.html.erb).

Stretch Challenges

1. You already have routes for pets#edit and pets#update, since you're calling resources :pets in routes.rb. Now set up controller methods for pets#edit and pets#update, as well as a view for editing pets (edit form).

2. Make sure your pets#update method also handles errors by redirecting if the user submits invalid data and displaying a flash message in the view.

3. Read the Rails docs for partials, and use a partial to DRY up the code in new.html.erb and edit.html.erb.