How in rails 4.1 enum prescribe in migration something like this?
class CreateFriendsUsers < ActiveRecord::Migration
def change
create_table :friends_users, id: false do |t|
t.integer :friend_id
t.integer :user_id
t.integer :status, [:active, :deactive]
end
end
end
this is join table for user and user
has_and_belongs_to_many :friends,
:class_name => "User",
:foreign_key => "user_id",
:association_foreign_key => "friend_id",
:join_table => "friends_users",
:after_add => :add_friend,
:after_remove => :remove_friend
Related
I am trying to save a person's Facebook friends into my database. I want to store the Facebook users in a table and then store their friendships in another table. The friendships would have the integer of the FacebookUser that requested the friendship and the integer of the friend, both of which are foreign keys to the facebook_users table. However I keep getting this message when I try to link the a user's facebook friends with friendships.
Error
ActiveRecord::HasManyThroughSourceAssociationNotFoundError: Could not find the source association(s) :friend or :friends in model Friendship. Try 'has_many :friends, :through => :friendships, :source
=> <name>'. Is it one of :FacebookUser or :FacebookFriend?
friendship.rb
class Friendship < ActiveRecord::Base
attr_accessible :facebook_user_id, :facebook_friend_id
belongs_to :FacebookUser
belongs_to :FacebookFriend, :class_name => :FacebookUser
end
facebook_user.rb
class FacebookUser < ActiveRecord::Base
attr_accessible :first_name, :gender, :last_name
has_many :friendships, :foreign_key => :facebook_user_id
has_many :friends, :through => :friendships, :source => :FacebookUser
end
Schema
create_table "facebook_users", :force => true do |t|
t.string "first_name"
t.string "last_name"
t.string "gender"
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end
create_table "friendships", :force => true do |t|
t.integer "facebook_user_id"
t.integer "facebook_friend_id"
end
the convention Rails uses is to use associations as defined by the class name and the foreign key. if you've set up your tables like above, you should change your models to the following.
class Friendship < ActiveRecord::Base
attr_accessible :facebook_user_id, :facebook_friend_id
belongs_to :facebook_user # implies a foreign key of facebook_user_id and class of FacebookUser
belongs_to :facebook_friend, class_name: 'FacebookUser' #implies a foreign key of facebook_friend_id
end
class FacebookUser < ActiveRecord::Base
attr_accessible :first_name, :gender, :last_name
has_many :friendships
has_many :friends, :through => :friendships, :source => :facebook_friend
end
I've read lots about self referential classes in Rails, but am still having problems getting them working.
I have a class of Articles and I want them to be able to refer to each other, from a source article to an outcome article - and then be able to find the reverse. So I'm trying to do a has_many through, using another class called Links.
My schema is
create_table "articles", :force => true do |t|
t.string "name"
t.text "body"
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "links", :force => true do |t|
t.integer "source_id"
t.integer "outcome_id"
t.string "question"
t.datetime "created_at"
t.datetime "updated_at"
end
The models are
class Article < ActiveRecord::Base
has_many :links_as_source, :foreign_key => "source_id", :class_name => "Link"
has_many :sources, :through => :links_as_source
has_many :links_as_outcome, :foreign_key => "outcome_id", :class_name => "Link"
has_many :outcomes, :through => :links_as_outcome
end
and
class Link < ActiveRecord::Base
belongs_to :source, :foreign_key => "source_id", :class_name => "Article"
belongs_to :outcome, :foreign_key => "outcome_id", :class_name => "Article"
end
I can create articles in the console, and I can link articles together, using a.outcomes << b but the link table is only storing the outcome_id, not the source_id.
What am I doing wrong?
I got this to work in the end. I changed the names - I don't know if that mattered. I did read somewhere that source was a silly name to use for something.
So this is what works:
My schema
create_table "article_relationships", :force => true do |t|
t.integer "parent_id"
t.integer "child_id"
...
end
create_table "articles", :force => true do |t|
t.string "name"
...
end
My article model
has_many :parent_child_relationships,
:class_name => "ArticleRelationship",
:foreign_key => :child_id,
:dependent => :destroy
has_many :parents,
:through => :parent_child_relationships,
:source => :parent
has_many :child_parent_relationships,
:class_name => "ArticleRelationship",
:foreign_key => :parent_id,
:dependent => :destroy
has_many :children,
:through => :child_parent_relationships,
:source => :child
In my Rails 3 project, I have a user model with a self referential join, through the follow model. I want to use this join table to find activity related to the followed user. I have almost everything set up correctly, except that the query generated by the join is totally ignoring the :primary_key option on the join model.
Here is the relevant schema for the relevant models:
create_table "users", :force => true do |t|
t.string "email", :default => "", :null => false
t.string "first_name"
t.string "last_name"
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "follows", :force => true do |t|
t.integer "user_id"
t.integer "followed_user_id"
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "activities", :force => true do |t|
t.integer "user_id"
t.text "body"
t.datetime "created_at"
t.datetime "updated_at"
end
Here's the associations in the models
class User < ActiveRecord::Base
has_many :follows
has_many :followed_users, :through => :follows
has_many :followed_activities, :through => :follows
has_many :activities
end
class Follow < ActiveRecord::Base
belongs_to :user
belongs_to :followed_user, :class_name => "User"
has_many :followed_activities, :primary_key => :followed_user, :foreign_key => :user_id, :class_name => "Activity"
end
The following work just fine:
u = User.first
u.follows # returns corresponding records from the follows table
u.followed_users # returns all users that u is following
u.followed_users.first.activities # returns all activity records corresponding to the first person the user is following
Follow.first.activities # same as the previous
However, the following just returns an empty array:
u.followed_activities
Here is the sql that is generated from the last statement:
Activity Load (0.2ms) SELECT `activities`.* FROM `activities` INNER JOIN `follows` ON `activities`.user_id = `follows`.id WHERE ((`follows`.user_id = 1))
The reason it isn't working is because it is trying to join use 'follows'.id as the primary key rather than 'follows'.followed_user.
Is this a bug, or do I have to repeat the :primary_key declaration somewhere on the user model? I can't find any mention anywhere in the Rails api, or anywhere else online.
Rails Version: 3.0.7
I've found it intuitive to daisy chain relationships with the 'nested_has_many_through' gem, http://rubygems.org/gems/nested_has_many_through which will be a standard part of rails 3.1 and could give you another tool to tackle the issue here
It will let you do something like this:
class Author < User
has_many :posts
has_many :categories, :through => :posts, :uniq => true
has_many :similar_posts, :through => :categories, :source => :posts
has_many :similar_authors, :through => :similar_posts, :source => :author, :uniq => true
has_many :posts_of_similar_authors, :through => :similar_authors, :source => :posts, :uniq => true
has_many :commenters, :through => :posts, :uniq => true
end
class Post < ActiveRecord::Base
belongs_to :author
belongs_to :category
has_many :comments
has_many :commenters, :through => :comments, :source => :user, :uniq => true
end
This has super-simplified my queries and collections. I hope you find an answer to your problem, it's a tough one!
Justin, you have 2 associations called "followed_activities". sure, they have different context (different models), but I'd like to ask you to try method inside the association block like this:
has_many :followed_users, :through => :follows do
def activities
end
end
I would like to join more than three tables in Rails 3.
My code is
class offer < ActiveRecord::Base
belongs_to :user
has_many :usercomments, :dependent => :destroy
has_many :comments, :through => :usercomments, :dependent => :destroy
end
class User < ActiveRecord::Base
has_many :usercomments, :dependent =>:destroy
has_many :comments,:through => :usercomments, :dependent => :destroy
has_many :offers, :dependent => :destroy
end
class Usercomment < ActiveRecord::Base
belongs_to :user
belongs_to :comment
belongs_to :offer
end
class Comment < ActiveRecord::Base
has_one :usercomment, :dependent => :destroy
has_one :offer, :through => :usercomments
has_one :user, :through => :usercomments
end
My schema is:
create_table "offers", :force => true do |t|
t.integer "step_id"
t.integer "user_id"
t.date "offerdate"
end
create_table "users", :force => true do |t|
t.string "firstname", :limit => 100, :default => ""
t.string "lastname", :limit => 100, :default => ""
t.string "email", :limit => 100
end
create_table "usercomments", :force => true do |t|
t.integer "user_id"
t.integer "airoffer_id"
t.integer "comment_id"
t.boolean "shared"
end
create_table "comments", :force => true do |t|
t.string "comment"
t.datetime "created_at"
t.datetime "updated_at"
end
and index.html.erb is:
<% airoffers.each do |airoffer| %>
???
<% end %>
In my html.erb page I would like to find a comment for an offer (offer_id) and an user (user_id).
It looks to me like what you want is:
class User < ActiveRecord::Base
has_many :comments
has_many :offers
end
class Offer < ActiveRecord::Base
has_many :comments
belongs_to :user
end
class Comment < ActiveRecord::Base
belongs_to :user
belongs_to :offer
end
If you want all the Comments that belong to a specific User and a specific Offer, just do Comment.where(:user_id => # :offer_id => #) and pass in the User and Offer you want.
Does this help?
This will give you an array of comments for User#123 en Offer#456
UserComment.find(:all, :conditions => {
:user_id => 123,
:offer_id => 456
}).collect(&:comment)
I would use it this way:
Comment.find(
:all,
:conditions => {
:user_id => 123,
:offer_id => 456
},
:join => :usercomment
)
OR:
Comment.find(
:all,
:conditions => [
"usercomments.user_id = ? AND usercomments.offer_id = ?",
123,
456
],
:join => :usercomment
)
Rails have a lot of beautiful ways to write queries.
Finally, i chose this solution
my code
class offer < ActiveRecord::Base
belongs_to :user
has_many :comments, :dependent => :destroy, :order => "updated_at DESC"
end
class User < ActiveRecord::Base
has_many :comments,:dependent => :destroy
has_many :offers, :dependent => :destroy
end
class Comment < ActiveRecord::Base
has_one :user, :dependent => :destroy
has_one :airoffer, :dependent => :destroy
end
schema
create_table "offers", :force => true do |t|
t.integer "user_id"
t.date "offerdate"
end
create_table "users", :force => true do |t|
t.string "firstname", :limit => 100, :default => ""
t.string "lastname", :limit => 100, :default => ""
t.string "email", :limit => 100
end
create_table "comments", :force => true do |t|
t.integer "user_id"
t.integer "offer_id"
t.string "comment"
t.datetime "created_at"
t.datetime "updated_at"
end
in offer_controller.rb
#offers = User.find(current_user.id).offers.includes(:comments)
and in my index.html.erb
<% #offers.each do |airoffer| %>
<% airoffer.comments[0].comment %>
<% end %>
I know, it's not the better solution, but in the first time i will use it.
I have a Comment class with a :foreign_key of post_id in the Post class.
class Comment < ActiveRecord::Base
belongs_to :post, :class_name => "Post", :foreign_key => "post_id", :counter_cache => true
belongs_to :author, :class_name => "User", :foreign_key => "author_id"
end
But my CreateComments migration does not define a database-level foreign key:
class CreateComments < ActiveRecord::Migration
def self.up
create_table :comments do |t|
t.column "post_id", :integer, :default => 0, :null => false
t.column "author", :string, :default => "", :limit => 25, :null => false
t.column "author_email", :string, :default => "", :limit => 50, :null => false
t.column "content", :text, :null => false
t.column "status", :string, :default => "", :limit => 25, :null => false
t.timestamps
end
end
def self.down
drop_table :comments
end
end
Instead post_id is a simple Integer column.
So, it seems that this foreign key relationship exists only in the mind of Rails, not at the database level.
Is this correct?
Also, is it necessary for the corresponding Post model to also declare its reciprocal foreign key relationship with Comments using the :foreign_key attribute or could that be omitted?
class Post < ActiveRecord::Base
set_table_name("blog_posts")
belongs_to :author, :class_name => "User", :foreign_key => 'author_id'
has_many :comments, :class_name => "Comment",
:foreign_key => 'post_id', :order => "created_at desc", :dependent => :destroy
has_many :categorizations
has_many :categories, :through => :categorizations
named_scope :recent, :order => "created_at desc", :limit => 5
end
The Rails default behaviour is that the column used to hold the foreign key on a model is the name of the association with the suffix _id added. The :foreign_key option lets you set the name of the foreign key directly. The associations between your Post and Comment model classes should look like this:
class Post < ActiveRecord::Base
has_many :comments
end
class Comment < ActiveRecord::Base
belongs_to :post
end
—Note that you don't need :class_name => "Post" in your Comment model. Rails already has that information. You should only be specifying :class_name and :foreign_key when you need to override the Rails' conventions.
You're correct that Rails maintains the foreign key relationships for you. You can enforce them in the database layer if you want by adding foreign key constraints.
I think you would benefit from reading A Guide to ActiveRecord Associations.