活动记录验证问题

Question

The Coursera course on Ruby on Rails that I am taking has us test the validations of two pages of our example, a posts page and a comments page. When I open up the example in my browser the validation on the comments page works just as it should, not allowing me to submit a comment without a post_id or a body. The problem is when I expect the same result from the posts page, I am allowed to submit anything without receiving an error message, the submission can have no title or body and still be accepted.

Here are the two segments of code in question:

Comments

class Comment < ActiveRecord::Base
 belongs_to :post
 validates_presence_of :post_id
 validates_presence_of :body
end

Posts

class Post < ActiveRecord::Base
 has_many :comments, dependent: :destroy
 validates_presence_of :title
 validates_presence_of :body
end

And the lecture from which I am practicing is here, the code starts at the 9 minute mark. https://class.coursera.org/webapplications-002/lecture/53

Since the comments works as it should, I want to know why my posts page is not working the same way. It does not seem like it is a typo. Any help would be greatly appreciated.

Answer 1

You can start by ruling out your model code by opening a new terminal and typing:

rails console

You will now be in independent ruby mode with your app loaded as well. You can now type:

@post = Post.new(:title => 'My post without a body')

Then to try and save to database you type:

@post.save

You will get a return of true if it's working, and false if it isn't, if it's false type:

@post.errors.full_messages

This should give you an answer as to why it isn't working. If the save does return true, then you know you're all good and we need to look elsewhere.

Answer 2

You may wish to use the new validates directive :

#app/models/post.rb
Class Post < ActiveRecord::Base
   validates :title, :body, presence: true
end

In regards to why this would not catch your "errors" that you've included in your form, there are a number of potential issues.

--

Controller

The most probable is that you'll not be populating the @active_record_object of your form.

This will be a problem because it won't give you the error messages (as mentioned by anti-fun ), but may also prevent you from being able to send the correct data you need.

Here's what I would do:

#app/controllers/posts_controller.rb
Class PostsController < ApplicationController
   def new
      @post = Post.new #-> sets the ActiveRecord object for your form
   end

   def create
      @post = Post.new post_params
      @post.save
   end

   private

   def post_params
      params.require(:post).permit(:title, :body)
   end
end

#app/views/posts/new.html.erb
<%= form_for @post do |f| %>
   <% if @post.errors.any? %>
      <% @post.errors.full_messages.each do |error| %>
          <%= error %>
      <% end %>
   <% end %>

   <%= f.text_field :title %>
   <%= f.text_field :body %>
   <%= f.submit %>
<% end %>

This should pass the required data to your controller, allowing you to validate it correctly