Understanding reflection in django for refactoring

Question

I am working on my first Django project and I need to understand the way reflection is used in django.

• I have the method category_autocomplete which I use with jQuery to get autocomplete for a category field.
• I need autocomplete in some more places but on different things. I think it might be a good idea to make into a class for reuse.
• I have started making the class but I am not sure how to proceed.

The problem is the way django uses the filter function. It has a parameter which goes like <param-name>_icontains. I can easily reproduce the lambda by using getattr and passing parameter name as a string but I cannot figure out how to use reflection to get the parameter name for the filter function.

Any idea how this can be done?

class Autocomplete():
    @staticmethod
    def get_json_autocomplete(self, cur_objects, func):
        results = []
        for cur_object in cur_objects:
            results.append(func(cur_object))
        return json.dumps(results)

    @staticmethod
    def autocomplete(self, request, class_name, attr_name):
        term = request.GET.get('term', '')
        data = Autocomplete.get_json_autocomplete(
            #Problem here
            class_name.objects.filter(attr_name=term),
            lambda x: getattr(x, attr_name)
        )
        return HttpResponse(data, 'application/json')

def _get_json_autocomplete(cur_objects, func):
    results = []
    for cur_object in cur_objects:
        results.append(func(cur_object))
    return json.dumps(results)

def category_autocomplete(request):
    term = request.GET.get('term', '')
    data = _get_json_autocomplete(
        Category.objects.filter(name__icontains=term),
        lambda x: x.name
    )
    return HttpResponse(data, 'application/json')

Answer 1

What I believe you're looking for is **, take a look here and here.

So that part of your code could be:

def autocomplete(self, request, class_name, attr_name):
    term = request.GET.get('term', '')
    data = Autocomplete.get_json_autocomplete(
        class_name.objects.filter(**{attr_name + '__icontains': term}),
        lambda x: getattr(x, attr_name)
    )
    return HttpResponse(data, 'application/json')