Categorize

categorize.py

def categorize(lst, attrs):
    """
    Generate a dictionary of lists where the keys are generated from
    some specified attribute of the items in the list
    """
    def dive_in(obj, attrs, index=0):
        if not obj or index >= len(attrs):
            return obj
        new_obj = getattr(obj, attrs[index])
        if len(attrs) > 0:
            return dive_in(new_obj, attrs, index+1)
        return new_obj

    categories = {}
    for item in lst:
        value = dive_in(item, attrs)
        if value not in categories:
            categories[value] = []
        categories[value].append(item)

    return categories


categorize(SomeModel.objects.all(), ['related_obj', 'related_obj_attr'])


# Result
{
	"value": [
		obj1,
		obj2
	],
	"other_value": [
		obj3
	],
}


# OR

categories = groupby(affiliates, lambda x: x.category.slug if x.category else None)
categories = {a:list(b) for a, b in categories}