Question

I’m working with DataMapper ORM in Codeigniter 2.1.2:

I have this kind of entities:

Person
-id             PRIMARY KEY
-name
-lastname
-age

Student
-person_id      PRIMARY KEY
-college
-notebook_color
-other attribute

Address
-id             PRIMARY KEY
-street
-number
-person_id

NOTE: Student has no own PK. It uses Person’s ID as PK.

So my problem is. I want to create a student:

$student = new Student();
$student->get_by_person_id($id);

I want $student to have all the data from person, including the addesses. I tried using include_related() to bring the fields from person, but this doesn’t bring the objects related.
I would like my $student look like:

$student                  ->id
                          ->name
                          ->lastname
                          ->age
                          ->college
                          ->notebook_color
                          ->other_attribute
                          ->address (array)
                             [0]    -> id
                                    -> street
                                    -> number

                             [1]    -> id
                                    -> street
                                    -> number

How can I get this to work?

Answer 1

You can not have a PK called ‘person_id’. Datamapper requires all PK’s to be called ‘id’. And FK’s should be called by their relation name, suffixed with ‘_id’. So the FK in address should be called ‘student_id’.

Also, Datamapper doesn’t support composites. So there is no way to merge records from Person and Student.