Control Query set in Django (filter,object Q)?

Question

Base On URL

querydict = {customer_type:val1,tag:[], city:[],last_contact:valdate}

show/?customer_type=All&tag=2,3&city=3&last_contact=29/12/2009

I am going to filter by made the method:

def get_filter_result(customer_type, tag_selected, city_selected, last_contact_filled):
    if customer_type=has value:
         I filter by this 
       #queryset = Customer.objects.filter(Q(type__name=customer_type))
    if tag = has value :
         I filter by this
         #queryset = Customer.objects.filter(Q(type__name=customer_type)
                                              Q(type__name=tag))
    if city = has value:
        I filter by this
        #queryset = Customer.objects.filter(Q(type__name=customer_type)
                                              Q(type__name=tag),
                                              Q(type__name=city))
    if last_contact = has value:
        I filter by this
        #queryset = Customer.objects.filter(Q(type__name=customer_type)
                                              Q(type__name=tag),
                                              Q(type__name=city),
                                              Q(type__name=last_contact))

Anybody Help give an idea to implement my method more simple and flexible than this? if value of them are missing or equal None(No value is passed) so if... else.... condition will control alots of time and code will be larger..

for example :
      show/?customer_type=All&tag=&city=&last_contact=
      show/?customer_type=All&tag=2,3&city=3&last_contact=29/12/2009
      show/?customer_type=&tag=2,3&city=3&last_contact=
      show/?customer_type=All&tag=2,3&city=&last_contact=29/12/2009

thanks

Answer 1

def get_filter_result(customer_type=None, tag_selected=None, city_selected=None, last_contact_filled=None):
    qdict = {}
    if customer_type is not None:
        qdict['type__name'] = customer_type
    if tag is not None:
        <repeat as appropriate>
    queryset = Customer.objects.filter(**qdict)

Answer 2

If you want to AND all your queries (like in your example), you can create dictionary of parameters, and then call filter method with this dictionary as an argument:

def get_filter_result(**kwargs):
    params = {}
    #delete items with empty strings
    for key in kwargs:
        if kwargs[key]:
            params[key] = kwargs[key]

    queryset = Customer.objects.filter(**params)