Rails 3: How to move code from view to controller (or model)?

Question

I have this in the index view:

<% @submissions.each do |submission| %>
    <tr>
        <td><%= submission.id %></td>
        <td><%= User.find_by_id(submission.user_id).name.to_s %></td>
    </tr>
<% end %>

I know I am not supposed to use find_by in the view.

How can I move this to the controller (or model)?

I tried to insert this in the index method of my submission controller and using the username variable but it doesn't work.

def index
    @submissions = Submission.all
    @submissions.each do |submission|
      username = User.find_by_id(submission.user_id).name.to_s
    end
end

You have a N+1 problem

aromero
– aromero

2013-02-27 23:52:54 +00:00
Commented Feb 27, 2013 at 23:52 — aromero
– aromero, Commented Feb 27, 2013 at 23:52

aromero · Accepted Answer · 2013-02-27 23:54:25Z

3

Model, add relation to user

class Submission
  belongs_to :user
end

Controller, eager load users to avoid N+1 queries.

def index
  @submissions = Submission.includes(:user).all
end

View, just project the user from each submission

<% @submissions.each do |submission| %>
    <tr>
        <td><%= submission.id %></td>
        <td><%= submission.user.name.to_s %></td>
    </tr>
<% end %>

answered Feb 27, 2013 at 23:54

aromero

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4 Comments

John Powel Over a year ago

Can I also use this approach on another model type when submission has_many types?

aromero Over a year ago

Yes, you can. In that case you will have many 'types', and you will need iterate them.

John Powel Over a year ago

Thank you, in my case, I just use submission has_one type since I only have one type for each submission. Another question though: my submission model belongs_to another model base, but the base model uses a different table name self.table_name = submission_bases. When I try to do the something like user, it doesn't work anymore, in my view I used submission.base but it cannot recognize the model base. In my submissions table I have a foreign key submission_base_id

John Powel Over a year ago

Never mind, I found the problem: need to set: belongs_to :base, :foreign_key => :submission_base_id

MrYoshiji · Accepted Answer · 2013-02-28 00:12:49Z

2

#in controller
def index
  @submissions = Submission.all
end

#in view
<% @submissions.each do |submission| %>
    <tr>
        <td><%= submission.id %></td>
        <td><%= submission.user.name %></td>
    </tr>
<% end %>

This code implies you have declared the following relations:

Submission belongs_to :user
User has_many :submissions (or has_one)

You can use eager loading (uses less queries to the DB) to improve the previous code:

@submissions = Submission.includes(:user).all

edited Feb 28, 2013 at 0:12

answered Feb 27, 2013 at 23:51

MrYoshiji

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Comments

windywindy · Accepted Answer · 2013-02-27 23:47:35Z

0

You can use an ActiveRecord association:

class Submission
  belongs_to :user

  # etc
end

Then in your view:

<td><%= submission.id %></td>
<td><%= submission.user.first_name</td> <!-- or whatever -->

answered Feb 27, 2013 at 23:47

windywindy

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