Join query in Ruby on Rails

Question

I have to make a join query on 2 tables in ruby on rails. It works fine, but object doesn't contains column in 2 tables that I have joined.

In controllers

@posts = Posts.select("*").joins(:users).joins(:categories).all

In view

<% @posts.each do |p| %>
<%= p.inspect %>
<% end %>

Result in view

Doesn't have column username in table user, etc...

Answer 1

Actually it should work.

Although the inspect only shows you the Post attributes, After doing this:

@posts = Post.select("*").joins(:users).joins(:categories).all

try to get to a specific attribute of a user

<% @posts.each do |p| %>
  <%= p.first_name %> # or any other user attribute
<% end %>

and it should show you the users first name.

if its not working you could do:

@posts = Post.select("posts.*, users.*, categories.*").joins(:users).joins(:categories).all

• pay attention that the table names in the select(...HERE...) are in their plural form, because its the name of the tables in the DB itself.

Answer 2

The object that comes after using the join query actually contains the data of both the tables, butt will not display it while giving puts or inspect.

we can directly call the attributes of the users table from the @posts object like,

<%= @posts.first.user_name %> or any other field.

Answer 3

Please try :

@posts = Posts.select("users.username, users.column2, users.column-n, categories.name, categories.column2, categories.column-n*").joins(:users, :categories).all