i have a user model with fields name and sex. And user can have an one-to-one association called "spouse" with another user, the association must be between a male user and a female user.
with the help of railscasts self-referential-association i create the basic association like this,
class User < ActiveRecord::Base
has_one :spouse_list
has_one :spouse, :through => :spouse_list
has_one :inverse_spouse_list, :class_name => "SpouseList", :foreign_key => "spouse_id"
has_one :inverse_spouse, :through => :inverse_spouse_list, :source => :user
end
class SpouseList < ActiveRecord::Base
belongs_to :spouse, :class_name => "User"
belongs_to :user
end
SpouseList has fields :spouse_id, :user_id,
above association can create many rows for single user and shows the first row if access spouse by #user.spouse_list.spouse.name
How can i restrict between a male user and a female user?
finally i made one-to-one self association for the below condition,
"User can have an one-to-one association called "spouse" with another user, the association must be between a male user and a female user"
added a field spouse_id to user model and created a self association with custom validation,
class User < ActiveRecord::Base
belongs_to :spouse, :class_name => 'User', :inverse_of => :base_user, :foreign_key => "spouse_id"
has_one :base_user, :class_name => 'User', :inverse_of => :spouse
validate :validate_spouse_gender
private
def validate_spouse_gender
errors.add(:spouse_id, 'could not be with same sex') if spouse && spouse.sex == sex
end
end
Now a male user A can only make association as spouse with another user B, if B is of gender female.
hope it helps someone.
Related
I have user model and a car model
I want to have a model which will hold the settings for each car and each user
so I do
class CarSettings < ActiveRecord::Base
belongs_to :user
belongs_to :car
end
for user:
has_many :car_settings
and for cars:
has_many :car_settings
has_many :users, :through => :car_settings
note the name CarSettings, this isn't a mistake, I want it to be settings and not setting
When I do
c=Car.first
c.users
I get
NameError: uninitialized constant Car::CarSetting
from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.2.12/lib/active_record/inheritance.rb:111:in `compute_type'
it is looking for a singular car_setting and not car_settings.
How can I fix this?
You can force the class name on the association using this option:
has_many :car_settings, :class_name => "CarSettings"
In my User model I have the following:
class User < ActiveRecord::Base
has_many :friendships, dependent: :destroy
has_many :friends, :class_name => "User", :foreign_key => "friend_id"
has_many :pending_friends,
:through => :friendships,
:conditions => "status = 'pending'",
:foreign_key => "user_id",
:source => :friend
has_many :requested_friends,
:through => :friendships,
:source => :friend,
:conditions => "status = 'requested'"
def friends
direct_friends | inverse_friends
end
In my Friendship model I have the following:
class Friendship < ActiveRecord::Base
belongs_to :user
belongs_to :friend, :class_name => "User", :foreign_key => "friend_id"
In my view I have created an array of each of the users' friends, shown below. This code works and populates the array with all the data from the friends' "User" database model attributes.
User.first.friends
However, I want to be able to call the users' friend's name's. So, for example, shouldn't I be able to do something like this?
User.first.friends.map(&:name)
How do I get an array containing just the friend's name's, instead of all the friend's user attributes? I would also appreciate if anyone could tell me why .first is used (I got that from here: Rails calling User record from Friends model), as it doesn't just get the first instance of the User's friends (it gets all the instances). And why does just doing:
User.friends
return an empty array?
Try method pluck:
User.first.friends.pluck(:name)
You should use first method to retrieve one object from table. The User is table with a lot of users.
I have two tables with a many to many relationship, through a third table. In the third table is a piece of data I need to assign when I build the relationships between the two tables, how can I use ActiveRecords build method to assign that?
Here is code to show what I mean:
class Company < Contact
has_many :contact_companies
has_many :people, :through => :contact_companies
accepts_nested_attributes_for :people, :allow_destroy => true
accepts_nested_attributes_for :contact_companies
end
class Person < Contact
has_many :contact_companies
has_many :companies, :through => :contact_companies
accepts_nested_attributes_for :companies, :allow_destroy => true
accepts_nested_attributes_for :contact_companies
end
class ContactCompany < ActiveRecord::Base
belongs_to :person
belongs_to :company
end
ContactCompany contains a data member called "position". What I want to do is something like:
c = Person.new
c.companies.build(:name => Faker::Company.name, :position => positions.sample)
EDIT:
When I try the code above I get "unknown attribute: position".
The c.companies.build line is attempting to build a Company object which does not have the position attribute (the ContactCompany does) hence the error. It looks like you are trying to set attributes on two different models, so you'll have to make sure you are setting the appropriate attribute on the right model:
# you can chain these calls but I separated them for readability
cc = c.contact_companies.build(:position => positions.sample)
cc.build_company(:name => Faker::Company.name)
Hi people, long time not been here. But I'm back because I need your help again please. I have a rails 3.0.9 app, and I'm working with nested forms and has_many through association. When i create an instance, it works great. The problems come when I try to edit. Here is an example for a better explanation. (table names and attributes are just for explaining)
Table Client
id
company_name
address
Table Worker
id
first_name
last name
Table Contact
id
client_id
worker_id
my models looks like these
class Worker < ActiveRecord::Base
has_many :contacts, :dependent => :destroy
has_many :clients, :through => :contacts, :foreign_key => 'client_id'
end
class Client < ActiveRecord::Base
has_many :contacts, :foreign_key => "client_id",:dependent => :destroy
has_many :workers, :through => :contacts, :foreign_key => 'worker_id'
accepts_nested_attributes_for :workers, :allow_destroy => false
end
class Contact < ActiveRecord::Base
belongs_to :worker, :foreign_key => "worker_id"
belongs_to :client, :foreign_key => "client_id"
end
Then in my form for create a client, I can create many workers, and rails make the association and creates the instances for the contacts table (by using nested forms).
The thing is, if I want to edit a client by removing a contact, the contact is not removed. As you can see I put this line in the clients model
accepts_nested_attributes_for :workers, :allow_destroy => false
I set the allow_destroy to false, because I don't want to delete the worker itself, I just want to remove the contact tuple.
Does anybody know how can I solve this?? Hope you can help me... Thanks
I've built a simple Friend model, which allows Users to have multiple friends. Here's what that looks like:
class Friend < ActiveRecord::Base
belongs_to :user
class User < ActiveRecord::Base
has_many :friends
Each friend record just has an id, user_id and friend_id. The user_id is the id of the user it belongs to and the friend_id is the id of user they are befriending.
Here's my problem
I'm not quite sure how to display a list of a particular user's friends. #user.friends will give me a list of all the friend records they have, but not the user accounts of those friends.
For instance, I am trying to build a show page for the friends controller:
class FriendsController < ApplicationController
def show
#user = current_user
end
SHOW.HTML.ERB
<% if #user.friends.count > 0 %>
<% #user.friends.each do |friend| %>
<div class="entry">
<%= friend.username %>
This does not work because friend in this case does not have username. I need to do something like this in my controller:
#friend = User.find_by_id(friend.friend_id)
But I'm not sure how I would call that in my view in the #user.friends loop. Any thoughts appreciated. Let me know if I need to be more clear.
UPDATE
I've updated my User model like so:
has_many :friends, :include => :user
has_many :friended_users, :through => :friends, :source => :user, :uniq => true
However, when I run #user.friended_users it's giving me the user_ids (which is the same as #user) rather than friend_ids.
How can I tweak that relationship so it's linking to the friend_id rather than user_id?
The more I think about it, I think I may not have set up the relationship properly in the first place. Maybe a User should has_many :users, through => 'friends', but that doesn't really make sense...
UPDATE
I've updated my models based on #twooface's input:
class User < ActiveRecord::Base
has_many :friendships
has_many :friends, :through => :friendships
class Friendship < ActiveRecord::Base
belongs_to :user
belongs_to :friend, :class_name => 'User'
class Friend < ActiveRecord::Base
has_many :friendships
has_many :users
I'm just not sure what my Friends table should look like. I assume it should have a primary key and a user_id? If I create a friendship and friend record, I can do friendship.user and friendship.friend and get the correct results, but user.friends gives me an empty hash...
I think your relations are built a bit wrong. Try something like this:
class User < ActiveRecord::Base
has_many :friends
has_many :friendships
has_many :friends, :through => :friendships
class Friendship < ActiveRecord::Base
belongs_to :user
belongs_to :friend, :class_name => 'User'
# This class has :user_id and :friend_id
Then everything will be simpler. Every user will have an array of friends that will be just users.
User.first.friends
Will return an array of Users that this User friends.
Hope this helps.