Hello,
I just stumbled upon a behaviour about associations I do not really
understand why Rails/ActiveRecord cannot get the connection. Using
activerecord (4.2.0.beta2).
To describe it, lets work with theses models:
class User < ActiveRecord::Base
has_many :project_participations
has_many :projects, through: :project_participations, inverse_of:
:users
end
class ProjectParticipation < ActiveRecord::Base
belongs_to :user
belongs_to :project
enum role: { member: 0, manager: 1 }
end
class Project < ActiveRecord::Base
has_many :project_participations
has_many :users, through: :project_participations, inverse_of:
:projects
end
A user can participate in many projects with a role as a member or a
manager. The connecting model is called ProjectParticipation.
I now have a problem using the associations on unsaved objects. The
following commands work like I think they should work:
first example
u = User.new
p = Project.new
u.projects << p
u.projects
=> #<ActiveRecord::Associations::CollectionProxy [#]>
u.project_participations
=> #<ActiveRecord::Associations::CollectionProxy [#<ProjectParticipation
id: nil, user_id: nil, project_id: nil, role: nil>]>
So far so good - AR created the ProjectParticipation by itself and I can
access the projects of a user with u.projects.
But it does not work if I create the ProjectParticipation by myself:
second example
u = User.new
pp = ProjectParticipation.new
p = Project.new
pp.project = p # assign project to project_participation
u.project_participations << pp # assign project_participation to user
u.project_participations
=> #<ActiveRecord::Associations::CollectionProxy [#<ProjectParticipation
id: nil, user_id: nil, project_id: nil, role: nil>]>
u.projects
=> #<ActiveRecord::Associations::CollectionProxy []>
Why are the projects empty? I cannot access the projects by u.projects
like
before, even the ProjectParticipation is there.
But if I go through the participations directly, the project shows up:
u.project_participations.map(&:project)
=> [#]
Shouldn’t it work like the first example directly:
u.projects returning me all projects not depending on whether I create
the join object by myself or not? Or how can I make AR aware of this?