Question

High guys. This isn’t behaving the way I think it should which means I’m doing it wrong;

class Tag < ActiveRecord::Base
  has_and_belongs_to_many :properties
end

class Property < ActiveRecord::Base
  has_and_belongs_to_many :tags

  def amenities
    tags.where(:classification => :amenity)
  end
end

So I have Properties and Tags. They have a HABTM relationship with a pivot table.

When I do a .tags on a property, I get the full list and if I do a .clear on that full list it correctly removes the associations from the database.

When I do a .amenities I get only those tags that are flagged with the classification of amenity correctly, but if I do a .clear on those results it fails to remove them but rather just does the .amenities query again in the console with an output of [].

So this means it’s just .clear‘ing the result array.. not the association which is what I actually want.

So the question then is; what is the correct way to .clear an association from a HABTM relationship while giving it essentially a where clause to limit which associations are being removed?

Thanks guys. Hope that wasn’t too confusing..

Answer 1

Instead of defining a method querying tags, you could add another tag association with conditions, like:

class Property < ActiveRecord::Base
  has_and_belongs_to_many :tags

  # this will be just like the tags association, except narrow the results
  # to only tags with the classification of 'amenity'
  has_and_belongs_to_many :amenities, 
                          :class_name => 'Tag', 
                          :conditions => { :classification => 'amenity' }

end

clear, and any other habtm assocation methods, should work as expected.