Rails外键混乱

Question

I'm trying to learn rails. I have 2 tables Users and Posts, I want to link the email address from Users to Posts but I'm not sure how to go about it.

I have pre-made the table but how to I go about adding a Users.email to the new select box, so far I have this in the index.html.erb.

 <tbody>
    <% @posts.each do |post| %>
      <tr>
        <td><%= post.title %></td>
        <td><%= post.time %></td>
        <td><%= post.body %></td>
        <td><%= post.user_id %></td>
        <td><%= link_to 'Show', post %></td>
        <td><%= link_to 'Edit', edit_post_path(post) %></td>
        <td><%= link_to 'Destroy', post, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>

And this in my form.html.erb

%= form_for(post) do |f| %>
  <% if post.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(post.errors.count, "error") %> prohibited this post from being saved:</h2>

      <ul>
      <% post.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :title %>
    <%= f.text_field :title %>
  </div>

  <div class="field">
    <%= f.label :time %>
    <%= f.datetime_select :time %>
  </div>

  <div class="field">
    <%= f.label :body %>
    <%= f.text_area :body %>
  </div>

  <div class="field">
    <%= f.label :user_id %>
    <%= f.number_field :user_id %>
  </div>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

As you can see I have a user_id field but how would I go about linking that to the primary key of Users? and then to do and email lookup? Thanks.

Answer 1

Assuming you had association between Post and User model,

If user login exists, then you can create post belonging to user like below,

current_user.posts.create(post_params)

If user login not exists, then you can have the select box in post creation screen to choose the user and send the user_id of that user on submit.

Saving user_id in post record is enough to associate post and user.

For example,

<%= f.collection_select :user_id, User.all, :id, :email %>

When viewing the posts, you can grab the user email like below,

<td><%= post.user.email %></td>

Update

To create association between Post and user model, run the following command.

rails g migration add_user_to_posts user:references
rake db:migrate