Rails Has_Many :Through Find by Extra Attributes in Join Model

Rails has_many :through Find by Extra Attributes in Join Model

How about adding something like this into your User model?

has_many  :active_events, :through => :event_users, 
          :class_name => "Event", 
          :source => :event, 
          :conditions => ['event_users.active = ?',true]

After that you should be able to get active events for a user just by calling:

User.first.active_events

Add an attribute to a joining model in Rails has_many through

I think you should create a separate model for this Recommendation, dependent of the Like model:

class Book < ActiveRecord::Base
  belongs_to :user
  has_many :comments
  has_many :commenters, :through => :comments, :source => :user 

class User < ActiveRecord::Base
  has_many :books
  has_many :comments
  has_many :commented_books, :through => :comments, :source => :book

class Comment < ActiveRecord::Base
  belongs_to :user
  belongs_to :book

Then, the logic to create a comment for a book:

# Books Controller
def show
  @book = Book.find(params[:id])
  @comment = @book.comments.build
end

# show view of the book
form_for @comment do |form|
  form.hidden_field :user_id, value: current_user.id
  form.hidden_field :book_id
  form.text_area :content # the name of the attribute for the content of the comment

  form.submit "Post comment!"
end

To list all the comments of a specific User:

# users controller (profile page)
def show
  @user = User.find(params[:id])
end

# show view of Users
@user.comments.includes(:book).each do |comment|
  "Comment on the book '#{comment.book.name}' :"
  comment.content
end

using join model attributes in rails has_many :through

solved with

class Group
  has_many :groups_users
  has_many :moderatorships, :class_name => "GroupsUser",:conditions => {:moderator => true}
  has_many :moderators, :through => :moderatorships, :class_name => "User", :source => :user
end

Preferred to Matt van Horn's answer because this one produces only one query when we select user info with @group.moderators, while his solution gives separate query for each moderator

edit: updated to answer Sizzlepants' question. moderators created with this code should have moderator attribute in join model set to true (rails uses :conditions while creating join model), also, if i'd have to code it now, i'd name groups_users memberships for readability.

how to access rails join model attributes when using has_many :through

In your example you have defined in Item model relationship as has_many for collection_items and collections the generated association method is collection_items and collections respectively both of them returns an array so the way you are trying to access here is wrong. this is primarily case of mant to many relationship. just check this Asscociation Documentation for further reference.

---

Related Topics