Collections of Custom Entities

rubyonrails-talk
1

I have two entities (Department and Project) that extends ActiveRecord::Base. The department is mapped to have many projects. When i make a query using the find(:all) (Department.find(:all)), i get a collection of the departments with the attributes(id, project_id) of the database. I would like to receive in each department one entity of the project class.

I will appreciate any help

2

For a 'has_many' association, the Department key should be in the Project class (not the other way as it appears from your post). You also need to specify the belongs_to side (Project belongs_to :department) and that is usually the easier one to help remember where to place the foreign key: a class belongs_to another class to which it holds a key.

class Department < ActiveRecord::Base   has_many :projects # usually a has many relationship uses the plural form end

class Project < ActiveRecord::Base   belongs_to :department # the belongs_to, though, is singular end

Department.find(:all, :include=>:projects) This will look up all the departments and eager load (SQL JOIN) the projects for each one.