has_many associations table confusing-Collection of common programming errors

2 years ago

admin

2 minutes

My goal here is to print list of users from specified city and category with their names, address and club name.Name and address display correctly but when i add club name,says undefined method memberships for #.I know this is because Club is in different model ,So the question is how do i access club name?I am really shallow in complex has_many realtionships.Can anybody make necesary corrections please,This is how far i got.Thank you in advance

MODELS

class User < ActiveRecord::Base
  has_many :memberships 
  has_many : clubs,:through =>:memberships
  belongs_to :category
  belongs_to :city
end

class Club < ActiveRecord::Base
  has_many :users 
  has_many :memberships 
  has_many : users ,:through =>:memberships
  belongs_to :city
end

class Membership < ActiveRecord::Base
  belongs_to :user
  belongs_to :club
end

class City < ActiveRecord::Base
  has_many :clubs 
  has_many :users  
end

class Category < ActiveRecord::Base
  has_many :users
end

CONTROLLER

  @users=User.where("category_id =? AND   city_id=?",Category.find(2),session[:city_id])
  @[email protected]
  @[email protected] #this gives undefined method membership

VIEW

    
   
   
    #attribute name is in the club model not membership

ROUTE

       devise_for :users
      resources :city,:club,:category

The line below returns an array instead of what you are expecting, i.e. User object.
```
@[email protected]
```
If users shown in the view belong to different clubs you should access them directly in the view. You can eager load the clubs if needed.

In your controller
```
@users=User.where(:category_id => Category.find(2), :city_id=>session[:city_id]).
  include(:clubs)
```
In your view
```
  
  
  
    
    
```

First of all, you have an error in Club class. You cant have 2 relations with the same name. Second one will override first.

has_many : users ,:through =>:memberships

should be

has_many :members, :through =>:memberships, :foreign_key => 'user_id'

The search should be:

@users = User.where(:category_id => 2, :city_id => 3).include(:clubs)

Or whatever it values you want to search by.The view is:


  
  
   #attribute name is in the club model not membership

Your routes are fine.

Originally posted 2013-11-09 22:49:54.