Duplicate an AppEngine Query object to create variations of a filter without affecting the base query

In my AppEngine开发者_StackOverflow社区 project I have a need to use a certain filter as a base then apply various different extra filters to the end, retrieving the different result sets separately. e.g.:

base_query = MyModel.all().filter('mainfilter', 123)

Then I need to use the results of various sub queries separately:

subquery1 = basequery.filter('subfilter1', 'xyz')
#Do something with subquery1 results here

subquery2 = basequery.filter('subfilter2', 'abc')
#Do something with subquery2 results here

Unfortunately 'filter()' affects the state of the basequery Query instance, rather than just returning a modified version. Is there any way to duplicate the Query object and use it as a base? Is there perhaps a standard Python way of duping an object that could be used?

The extra filters are actually applied by the results of different forms dynamically within a wizard, and they use the 'running total' of the query in their branch to assess whether to ask further questions.

Obviously I could pass around a rudimentary stack of filter criteria, but I'd rather use the Query itself if possible, as it adds simplicity and elegance to the solution.

There's no officially approved (Eg, not likely to break) way to do this. Simply creating the query afresh from the parameters when you need it is your best option.

As Nick has said, you better create the query again, but you can still avoid repeating yourself. A good way to do that would be like this:

#inside a request handler

def create_base_query():
  return MyModel.all().filter('mainfilter', 123)

subquery1 = create_base_query().filter('subfilter1', 'xyz')
#Do something with subquery1 results here

subquery2 = create_base_query().filter('subfilter2', 'abc')
#Do something with subquery2 results here