Rails HABTM还是has_many？

Question

I have two models: Person, and Property. In the Person model I have a field which stores the role of the person(tenant, owner, admin, contractor, etc). Since each property will belong to an owner and potentially have one or more tenants, I thought this would be a good opportunity to use the HABTM model relation.

Do I have this right?

Also, how do I reference the attached model? Assuming my join model is named PropertiesPeople, and I wanted to fetch the tenants for a particular property, would that be the following?

@property.people.where(:role => "tenant")

Answer 1

If the same Person can have more than one Property, you should can use HABTM. Something like this:

class Person < ActiveRecord::Base
  # in the people table you are storing the 'role' value
  has_and_belongs_to_many :properties, join_table: 'people_properties'
end

class Property < ActiveRecord::Base
  has_and_belongs_to_many :people, join_table: 'people_properties'
end

You should create the intermidiate table people_properties with the foreign keys, person_id and property_id .

The problem of this approach is that if a Person can be "tenant" in one property and "contractor" in another, for example, you can't store that information. In that case I will suggest using an intermidiate model, like this

class Person < ActiveRecord::Base
    has_many :property_people
    has_many :properties, through: :property_people
end

class PropertyPerson
    # now you store here the 'role' value
    belongs_to :person
    belongs_to :property
end

class Property < ActiveRecord::Base
    has_many :property_people
    has_many :people, through: :property_people
end

I don't know for sure if the class names are successfully inferred from the relationships names, in that case you can always indicate class_name or even the foreign_key for the associations. Also you can indicate the table for a model, using self.table_name=