Question

I have the following model setup – a User is interested in projects in many project
Categories. Each Project has many categories. Like so:

class User
  has_many :projects
  has_and_belongs_to_many :project_categories

class Project
  belongs_to :user
  has_and_belongs_to_many :project_categories

class ProjectCategory
  has_and_belongs_to_many :projects
  has_and_belongs_to_many :users

Now, I’d like to do a find for projects with any of the catogories
that a certain user are interested in, i.e. if a user is interested in
project categories A,B,C then I’d like to find projects which are part
of one or more of those project categories.

Anyone?

Answer 1

Thanks for the help! Being a much too eager noob at the moment I haven’t gone through all possible AR solutions, but it would be interesting if something like this brakes the AR abstractions as Pierre said. I went with a modified version of Randy’s suggestion:

pids = Project.find_by_sql ["SELECT project_id FROM project_categories_projects JOIN project_categories_users ON project_categories_projects.project_category_id = project_categories_users.project_category_id WHERE user_id = ?", current_user.id]
mytags_projects = Project.find(pids.collect(&:project_id), :limit => 10, :order => "created_at DESC")