creating associations

Signed-off-by: man13 <man13@inf.ufpr.br>

app/models/mime_type.rb

 class MimeType < ActiveRecord::Base
+  has_and_belongs_to_many :object_types
 end

app/models/object_type.rb

 class ObjectType < ActiveRecord::Base
   has_many :learning_objects
+  has_and_belongs_to_many :mime_types
 
   validates :name, presence: true
 end

db/migrate/20160310124058_remove_mime_types_from_object_types.rb

+class RemoveMimeTypesFromObjectTypes < ActiveRecord::Migration
+  def change
+    remove_column :object_types, :mime_type, :string
+  end
+end

db/migrate/20160310124059_add_associations_to_object_types_and_mime_types.rb

+class AddAssociationsToObjectTypesAndMimeTypes < ActiveRecord::Migration
+  def change
+    create_table :mime_types_object_types do |t|
+      t.belongs_to :object_type, index: true
+      t.belongs_to :mime_type, index: true
+    end
+  end
+end