def add(self, data, connector):
"""
Add a node to the where-tree. If the data is a list or tuple, it is
expected to be of the form (obj, lookup_type, value), where obj is
a Constraint object, and is then slightly munged before being stored
(to avoid storing any reference to field objects). Otherwise, the 'data'
is stored unchanged and can be any class with an 'as_sql()' method.
"""
if not isinstance(data, (list, tuple)):
super(WhereNode, self).add(data, connector)
return
obj, lookup_type, value = data
if is_iterator(value):
# Consume any generators immediately, so that we can determine
# emptiness and transform any non-empty values correctly.
value = list(value)
# The "value_annotation" parameter is used to pass auxilliary information
# about the value(s) to the query construction. Specifically, datetime
# and empty values need special handling. Other types could be used
# here in the future (using Python types is suggested for consistency).
if isinstance(value, datetime.datetime):
value_annotation = datetime.datetime
elif hasattr(value, 'value_annotation'):
value_annotation = value.value_annotation
else:
value_annotation = bool(value)
if hasattr(obj, "prepare"):
value = obj.prepare(lookup_type, value)
super(WhereNode, self).add((obj, lookup_type, value_annotation, value),
connector)
def _prepare_data(self, data):
"""
Prepare data for addition to the tree. If the data is a list or tuple,
it is expected to be of the form (obj, lookup_type, value), where obj
is a Constraint object, and is then slightly munged before being
stored (to avoid storing any reference to field objects). Otherwise,
the 'data' is stored unchanged and can be any class with an 'as_sql()'
method.
"""
if not isinstance(data, (list, tuple)):
return data
obj, lookup_type, value = data
if is_iterator(value):
# Consume any generators immediately, so that we can determine
# emptiness and transform any non-empty values correctly.
value = list(value)
# The "value_annotation" parameter is used to pass auxilliary information
# about the value(s) to the query construction. Specifically, datetime
# and empty values need special handling. Other types could be used
# here in the future (using Python types is suggested for consistency).
if (isinstance(value, datetime.datetime)
or (isinstance(obj.field, DateTimeField) and lookup_type != 'isnull')):
value_annotation = datetime.datetime
elif hasattr(value, 'value_annotation'):
value_annotation = value.value_annotation
else:
value_annotation = bool(value)
if hasattr(obj, "prepare"):
value = obj.prepare(lookup_type, value)
return (obj, lookup_type, value_annotation, value)
def _get_choices(self):
if is_iterator(self._choices):
choices, self._choices = tee(self._choices)
return choices
else:
return self._choices
