Question

I started to learn Rails a few days ago and also have not much experience with Ruby too. The problem with me now is trying to find all the projects of a certain user, given the relationship below.

User Model

class User < ActiveRecord::Base
    has_many :projects_users
    has_many :projects, :through => :projects_users
    attr_accessible :email, :firstname, :id, :lastname, :password, :username, :password
    has_secure_password
end

Project Model

class Project < ActiveRecord::Base
    has_many :projects_users
    has_many :users, :through => :projects_users
    attr_accessible :date_created, :id, :name
end

Project_User Model

class ProjectsUsers < ActiveRecord::Base
    belongs_to :project
    belongs_to :user
end

My attempt so far is:

@projectuserid = ProjectsUsers.find(:all, :conditions => "user_id=#{session[:user_id]}")
@projects = Project.all(@projectuserid)

But it seems like @projectuserid is an array itself so the query doesn’t work. I know it could be achieved in one line of code for this HABTM relationship model, but still I have so little knowledge about Rails.

Another approach of mine looks like this, but a blank result returned:

@projects = Project.find :all,
         :conditions => "id in (select distinct project_id from projects_users where user_id=#{session[:user_id]})"

Answer 1

The error is probably be due to the fact that you aren’t following Rails’ naming convention.

• Models should have names in singular form: ProjectUser rather than ProjectsUsers.
• If you aren’t planning to save any additional data in the ProjectUser model, you’d be better off just using a normal has_and_belongs_to_many relation. In other words: no “join model”, just a join table named projects_users.

So either you do this:

class User < ActiveRecord::Base
    has_and_belongs_to_many :projects
end

class Project < ActiveRecord::Base
    has_and_belongs_to_many :users
end

Or you do this:

class User < ActiveRecord::Base
    has_many :project_users
    has_many :projects, through: :project_users
end

class Project < ActiveRecord::Base
    has_many :project_users
    has_many :users, through: :project_users
end

class ProjectUser < ActiveRecord::Base
    belongs_to :user
    belongs_to :project
end

In both cases you can do this: user.projects and project.users