Rails - how do you display data from the database

Im fairly new to Rails and i am simply trying to display the user_id of a record in a sqlite3 database on a page. Here is my code:

Model

class User < ActiveRecord::Base
  set_primary_key :user_id
  has_one :开发者_运维问答user_id
end

Controller

class HomeController < ApplicationController
  def index
    @users = User.find(0)
  end
end

View

<%= User.users.user_id %>

Im sure im making a silly mistake.

Alternatively in your view:

<% User.all.each do |user| %>
  <%= user.id %>
<% end %>

This will print out the user_id for all the records in User

If you only want a UID for a user object it's fairly standard to let rails sort this out for you, so you just generate the required attributes of your table and don't include user_id. However it might be the case you want this user_id in which case ignore what I just said. You don't need the has_one relation unless you have another model named user_id (which is possible I guess)

The index method is generally meant to return all users, or at least a subset (if you use pagination for example) I would therefore recommend using the following in an index method

User.find :all  

Notice I have left the brackets off, it doesn't make a difference but is a rails convention (it make it looks more like a DSL).

To return 1 user you might want a method like this

# GET /posts/1
def show
   @user = User.first      
end

But convention states the id would be specified by url sent, so it might look more like this

# GET /posts/1
def show
   @user = User.find params[:id]      
end

if you then access a url like the one specified above the show method (/posts/1, where 1 is the ID)

The view for this method should look something like this:

<%= @user.user_id %>

Note the @user is a member variable passed to the view by the show method, in this case an instance of a user with the id 1, and you are accessing the user_id attribute of that instance so you don't need the User. as this would be calling on a class method not a method of an instance of the user object.

To answer your specific question it should look more like

Model

class User < ActiveRecord::Base
  set_primary_key :user_id
end

Controller

class HomeController < ApplicationController
  def show
    @user = User.first
  end 
end

Accessing the show view with /users/0

The View would contain

<%= @user.user_id %>

EDIT:

To display the user logged in you will probably need a user session object which is created when a user logs in and destroyed when the user logs out. The user session object should have an associated user object, you can then query the user_session object for which user is logged.

I strongly recommend using authlogic, it's simple enough to know whats going on but does the trick

To print the whole DB use;

Model.all

e.g

User.all

Are you sure about the User.find(0) here? Doesn't the ID start with one? To be safe, do

@user = User.first

The in the view, you would do

<%= @user.user_id %>