Ruby on Rails：显示下拉菜单，其中包含来自其他模型的数据

Question

I have a Ruby on Rails system whereby I have the tables: Users, UserAccounts, Accounts, and Emails with the schemas:

User (id, firstname, surname, password)
UserAccount (user_id, account_id)
Account (id, emailaddress, port, domain)
Email (id, account_id, subject, message)

What I am trying to do is when creating new email, I want all of the user's accounts' emailaddress variable to display on the view in a drop down menu and when the user clicks save I want the account_id to be saved in the Emails table.

At the minute I can display the account_id in a drop down menu on the views/emails/_form.html.erb with the following line of code:

<%= f.collection_select :account_id, Useraccount.where(user_id: session[:user_id]), :account_id, :account_id %>

But I cannot change this to show the email address, I have tried the following code to do so:

<%= f.collection_select :account_id, Useraccount.where(user_id: session[:user_id]), :account_id, :Account.where(id: account_id).email %>

But this gives me the error undefined local variable or method account_id' for #<#:0x72cde60>`

Can anyone please help?

My whole code for the form is:

<%= form_for @email do |f| %>

  <% if @email.errors.any? %>
    <div id="error_explanation">
      <h2>
        <%= pluralize(@email.errors.count, "error") %> prohibited this email from being saved:
      </h2>
      <ul>
        <% @email.errors.full_messages.each do |msg| %>
          <li><%= msg %></li>
        <% end %>
      </ul>
    </div>
  <% end %>
 <%= f.collection_select :account_id, Useraccount.where(user_id: session[:user_id]), :account_id, :Account.where(id: account_id).email %>
  <p>
    <%= f.label :subject %><br>
    <%= f.text_field :subject %>
  </p>

  <p>
    <%= f.label :message %><br>
    <%= f.text_area :message %>
  </p>

  <p>
    <%= f.submit %>
  </p>

Answer 1

You haven't posted quite enough code to be able to help you very much. At least need to see the form that you are putting that collection_select on... assuming that it is a form for the new email you are wanting to send?

BTW it is very unusual to have Active Record class names that are plural. Breaking Rails naming conventions is a good way to get yourself into confusing situations.

Answer 2

It is easier to do with select instead of collection_select . I also assume that you have has_many through association in User model.

f.select :account_id, User.find(session[:user_id]).accounts.map{ |a| [a.emailaddress, a.id] }

collection_select takes methods names as arguments and it just won't work in your case.