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"
Related
I have a class with a nested association to itself:
class Location < ActiveRecord::Base
has_many :location_gateways
has_many :gateways, through: :location_gateways, class_name: "Location", :dependent => :destroy
accepts_nested_attributes_for :gateways, reject_if: :all_blank, allow_destroy: true
belongs_to :location, optional: true
end
The connecting model:
class LocationGateway < ActiveRecord::Base
belongs_to :location, :class_name => "Location"
belongs_to :gateway, :class_name => "Location"
end
Now I would like to make a form that can create a Location and some gateways but I get an Gateway must exist error when I submit it (the call to Location.new)
I'm assuming this is because the model Gateway doesn't exist. How can I make rails understand that it should create another Locationand not a Gateway?
Found no way around this error. I had to make a new class Gateway that inherits from Location and add a type to Locations (STI).
I have two classes (Game and Report) and want to link them with an additional attribute (default = yes or no).
The game should then have default_reports and optional_reports.
The association is then updated by selecting the default and optional reports in a select (multiple) in the games create/edit form.
I have tried using has_many and through as well as polymorphic associations, but nothing seems to fit the use case, where the associated objects are fixed and you only want to manage associations.
class Game < ActiveRecord::Base
has_many :game_reports
has_many :reports, :through => :game_reports
end
class Report < ActiveRecord::Base
has_many :game_reports
has_many :games, :through => :game_reports
end
class GameReport < ActiveRecord::Base
belongs_to :game
belongs_to :report
end
Any help is appreciated!
Thanks
this is just the model. the view and form to create the records is an entirely different matter.
you can always add a conditions option to has_many. I'm assuming you're going to add default to game_reports so change your class to something like.
class Game < ActiveRecord::Base
has_many :game_reports
has_many :reports, :through => :game_reports
has_many :default_reports, through: :game_reports, source: :report, conditions: { game_reports: { default: true } }
end
Rails 4.2+, use a Polymorphic association with scope and specify the foreign_key and foreign_type options.
class GameReport
belongs_to :report, :polymorphic => true
end
class Game
has_many :game_reports, :as => :report, :dependent => :destroy
has_many :reports, -> { where attachable_type: "GameReport"},
class_name: GameReport, foreign_key: :game_report_id,
foreign_type: :game_report_type, dependent: :destroy
end
Other approachs:
Rails Polymorphic Association with multiple associations on the same model
I need to assign students (users) to classes (studentclasses)
I have a simple many-to-many relationship using 3 tables:
studentclasses (lesson details)
users (user... student info)
studentclass_users (Join table containing user_id and studentclass_id)
I'm using has_many :through and my models look like the following:
studentclass.rb
class Studentclass < ActiveRecord::Base
has_many :studentclass_users
has_many :users, :through => :studentclass_users
end
user.rb
class User < ActiveRecord::Base
...more here...
has_many :studentclass_users
has_many :studentclasses, :through => :studentclass_users
end
studentclass_users.rb
class StudentclassUsers < ActiveRecord::Base
belongs_to :studentclass
belongs_to :user
end
For testing purposes, I'm just using a hidden field in my studentclass new view partial to tack on a user id when creating the class and it is as follows:
_new.html.erb
<%= hidden_field_tag "studentclass[user_ids][]", 29%>
And in my studentclass controller:
studentclasses_controller.rb
def new
#studentclass = Studentclass.new
end
def create
#studentclass = Studentclass.new(params[:studentclass])
#studentclass.save!
end
My params comes back:
Parameters: {"utf8"=>"✓", "authenticity_token"=>"MjBTf4rtcyo8inADrSxPZB3vLOKtlZRVFlQJJzfCqWs=", "studentclass"=>{"class_title"=>"hjhkj", "user_ids"=>["29"]}, "commit"=>"Save"}
which seems fine but I get the following error:
NameError (uninitialized constant ActiveRecord::HasManyThroughSourceAssociationMacroError):
I think this is something simple with naming maybe? Any help would be appreciated
So if I have the following relationship
class Item < ActiveRecord::Base
has_many :item_user_relationships
has_many :users, :through => :item_user_relationships
end
class User < ActiveRecord::Base
has_many :item_user_relationships
has_many :items, :through => :item_user_relationships
end
class ItemUserRelationship < ActiveRecord::Base
belongs_to :item
belongs_to :user
attr_accessible :role
end
What's the rails way to include the role attribute when listing all the Users of an Item?
#users = #item.users # I want to include the role as part of a user
Thanks!
UPDATE: I'm still having trouble with this. My goal is to get an array of User models that have their role included in the attributes.
I'm note sure if I understand you correctly, but maybe this is what you want?
#users = #item.users
#users.each do |user|
puts user.item_user_relationships.first.role
end
Hi im quite beginner in rails. i have a problem suggestion will be appreciated.
i have two model "user" and "asset"
an "asset" is created by a "user" and asset" can be assigned to a "user" schema is
Asset { id,name,creator_id,assigned_to_id,price,...}
User{ id,name,....}
now in Asset model class association are
class Asset < ActiveRecord::Base
{
#validation
belongs_to :creator ,:class_name=>'User'
belongs_to :assigned_to, :class_name=>'User' ,:foreign_key=>'assigned_to_id'
}
and User Model is
class User < ActiveRecord::Base
{
#any validation and other stuff
has_many :assets #did not specify either this association is for creator , or assigned_to user.how can is specify that??
}
now in Asset show view i can obtain creator name with
#asset.creator.name
but can't assigned_to name
#asset.assigned_to.name =>(error is )undefined method `first_name' for nil:NilClas
and
#asset.assigned_to_id.name=>(error is) undefined method `first_name' for 1:Fixnum
any suggestion how can i make double association with same model
ok solution was in my last comment.
Multiple relation with same model
class Asset < ActiveRecord::Base
belongs_to :creator ,:class_name=>'User'
belongs_to :assigned_to, :class_name=>'User'
end
user.rb
class User < ActiveRecord::Base
has_many :created_assets, :foreign_key => 'creator_id', :class_name => 'Asset'
has_many :assigned_assets , :foreign_key => 'assigned_to_id', :class_name => 'Asset'
end