python - Run code after objects list is created to alter them -

After the object is generated, I want to run the code on the object list of ToManyField .

I have the following code:

  class ResourceB (ModelResource): x = ForeignKey ... y = ForeignKey ... z = ForeignKey ... def alter_list_data_to_serialize ( Change the resources to Resource A (Model Resource): b = ToManyField (ResourceB, 'b', complete = true) ...  

When I try to access the URI of ResourceA , I think that alter_list_data_to_serialize has not been called at all. Why? How can I change the contents of ToManyField after the creation of dehydration ?