gistfile1.py

from mongoengine import Document, StringField, ReferenceField, BooleanField

class A(Document):                                           
    a = StringField()


class B(Document):
    b = StringField()
    boolfield = BooleanField(default=False)
    ref = ReferenceField(A)


A1 = A(a='abcde')
A1.save()
<A: A object>

A2 = A(a='xyz')
A2.save()
<A: A object>

B11 = B(b='bcd', ref=A1)
B11.save()
<B: B object>

B12 = B(b='bbb', boolfield=True, ref=A1)
B12.save()
<B: B object>

B21 = B(b='zzz', ref=A2)
B21.save()
<B: B object>

B22 = B(b='yyy', boolfield=True, ref=A2)

B22.save()
<B: B object>

a_query = A.objects(a='abcde')
a_query
[<A: A object>]

b_query = B.objects(ref__in=a_query)
b_query
[<B: B object>, <B: B object>]

b_query_bool = b_query.filter(boolfield=True)
b_query_bool

gistfile2.sh

/dev/mongoengine/queryset.pyc in __repr__(self)
   1968         for i in xrange(REPR_OUTPUT_SIZE + 1):
   1969             try:
-> 1970                 data.append(self.next())
   1971             except StopIteration:
   1972                 break

/dev/mongoengine/queryset.pyc in next(self)
   1013                 return self._get_as_pymongo(self._cursor.next())
   1014 
-> 1015             return self._document._from_son(self._cursor.next())
   1016         except StopIteration, e:
   1017             self.rewind()

/dev/mongoengine/queryset.pyc in _cursor(self)
    605         if self._cursor_obj is None:
    606 
--> 607             self._cursor_obj = self._collection.find(self._query,
    608                                                      **self._cursor_args)                                                                                                                                                            
    609             # Apply where clauses to cursor


/dev/mongoengine/queryset.pyc in _query(self)
    387     def _query(self):
    388         if self._mongo_query is None:
--> 389             self._mongo_query = self._query_obj.to_query(self._document)
    390             if self._class_check:
    391                 self._mongo_query.update(self._initial_query)

/dev/mongoengine/queryset.pyc in to_query(self, document)
    208 
    209     def to_query(self, document):
--> 210         query = self.accept(SimplificationVisitor())
    211         query = query.accept(QueryTreeTransformerVisitor())
    212         query = query.accept(QueryCompilerVisitor(document))

/dev/mongoengine/queryset.pyc in accept(self, visitor)
    259                 self.children[i] = self.children[i].accept(visitor)
    260 
--> 261         return visitor.visit_combination(self)
    262 
    263     @property

/dev/mongoengine/queryset.pyc in visit_combination(self, combination)
     78             if all(isinstance(node, Q) for node in combination.children):
     79                 queries = [node.query for node in combination.children]
---> 80                 return Q(**self._query_conjunction(queries))
     81         return combination
     82 

/dev/mongoengine/queryset.pyc in _query_conjunction(self, queries)
     96 
     97             query_ops.update(ops)
---> 98             combined_query.update(copy.deepcopy(query))
     99         return combined_query
    100 

/usr/lib/python2.7/copy.pyc in deepcopy(x, memo, _nil)
    161     copier = _deepcopy_dispatch.get(cls)
    162     if copier:
--> 163         y = copier(x, memo)
    164     else:
    165         try:

/usr/lib/python2.7/copy.pyc in _deepcopy_dict(x, memo)
    255     memo[id(x)] = y
    256     for key, value in x.iteritems():
--> 257         y[deepcopy(key, memo)] = deepcopy(value, memo)
    258     return y
    259 d[dict] = _deepcopy_dict

/usr/lib/python2.7/copy.pyc in deepcopy(x, memo, _nil)
    188                             raise Error(
    189                                 "un(deep)copyable object of type %s" % cls)
--> 190                 y = _reconstruct(x, rv, 1, memo)
    191 
    192     memo[d] = y

/usr/lib/python2.7/copy.pyc in _reconstruct(x, info, deep, memo)
    332     if state:
    333         if deep:
--> 334             state = deepcopy(state, memo)
    335         if hasattr(y, '__setstate__'):
    336             y.__setstate__(state)

/usr/lib/python2.7/copy.pyc in deepcopy(x, memo, _nil)
    161     copier = _deepcopy_dispatch.get(cls)
    162     if copier:
--> 163         y = copier(x, memo)
    164     else:
    165         try:

/usr/lib/python2.7/copy.pyc in _deepcopy_dict(x, memo)
    255     memo[id(x)] = y
    256     for key, value in x.iteritems():
--> 257         y[deepcopy(key, memo)] = deepcopy(value, memo)
    258     return y
    259 d[dict] = _deepcopy_dict

/usr/lib/python2.7/copy.pyc in deepcopy(x, memo, _nil)
    172             copier = getattr(x, "__deepcopy__", None)
    173             if copier:
--> 174                 y = copier(memo)
    175             else:
    176                 reductor = dispatch_table.get(cls)

/envs/alwaysdata/lib/python2.7/site-packages/pymongo/collection.pyc in __call__(self, *args, **kwargs)
   1401                             self.__name)
   1402         raise TypeError("'Collection' object is not callable. If you meant to "
   1403                         "call the '%s' method on a 'Collection' object it is "
   1404                         "failing because no such method exists." %
-> 1405                         self.__name.split(".")[-1])
                                                                                                                                                                                                                                             
TypeError: 'Collection' object is not callable. If you meant to call the '__deepcopy__' method on a 'Collection' object it is failing because no such method exists.