Associations

I’d like to do something like this…in English, a Teacher is in a town
(easy).

They also can have qualifications (from none to lots). How do I do this,
I mean I can see a Teacher could have a QualificationID field which
could have could contain numbers like 3,4,6 (meaning they have
qualifications of X, Y and Z). How do I do it in rails associations?

Teacher (Belongs to a Location)

  • FirstName
  • LastName
  • EmailAddress
  • MobilePhoneNumber
  • LocationID
  • QualificationID(s) <—

Location (Has Many Teachers)

  • Name

Qualification <— what to do here?

  • Name

Ultimately I’d like to do things like Teacher.Location.name (easy).

I’d like to do Teacher.Qualifications also (Not sure how to express this
but you get the idea).

Any help appreciated…

On 16 Apr 2009, at 15:36, bingo bob wrote:

I’d like to do something like this…in English, a Teacher is in a town
(easy).

They also can have qualifications (from none to lots). How do I do
this,
I mean I can see a Teacher could have a QualificationID field which
could have could contain numbers like 3,4,6 (meaning they have
qualifications of X, Y and Z). How do I do it in rails associations?

sounds like you need a has many through (or has and belongs to many)
between teachers and qualifications, since I assume that many teachers
may have the same qualification. This join model could also hold data
like when the qualification was awarded etc.

Fred

You can always add an assignment table like this:

class Teacher < ActiveRecord::Base
belongs_to :location
has_many :qualifications

location_id

end

class Location < ActiveRecord::Base
has_many :teachers
end

class Qualification < ActiveRecord::Base
belongs_to :quality
belongs_to :user

teacher_id, quality_id

end

class Quality < ActiveRecord::Base
has_many :qualifications
end

User.location # New York
User.qualifications # List of qualities

Er, sorry about that. Replace any instances of “user” you saw in there
with “teacher”, lost my train of thought there for a bit.

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