diff options
| -rw-r--r-- | django/db/models/query.py | 13 | ||||
| -rw-r--r-- | django/db/models/sql/query.py | 18 | ||||
| -rw-r--r-- | docs/db-api.txt | 23 |
3 files changed, 53 insertions, 1 deletions
diff --git a/django/db/models/query.py b/django/db/models/query.py index 3011b9d9a6..65048c7ba8 100644 --- a/django/db/models/query.py +++ b/django/db/models/query.py @@ -28,6 +28,17 @@ class QuerySet(object): # PYTHON MAGIC METHODS # ######################## + def __getstate__(self): + """ + Allows the Queryset to be pickled. + """ + # Force the cache to be fully populated. + len(self) + + obj_dict = self.__dict__.copy() + obj_dict['_iter'] = None + return obj_dict + def __repr__(self): return repr(list(self)) @@ -37,7 +48,7 @@ class QuerySet(object): # whilst not messing up any existing iterators against the queryset. if self._result_cache is None: if self._iter: - self._result_cache = list(self._iter()) + self._result_cache = list(self._iter) else: self._result_cache = list(self.iterator()) elif self._iter: diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py index bfed984953..7e9fb00418 100644 --- a/django/db/models/sql/query.py +++ b/django/db/models/sql/query.py @@ -99,6 +99,24 @@ class Query(object): memo[id(self)] = result return result + def __getstate__(self): + """ + Pickling support. + """ + obj_dict = self.__dict__.copy() + del obj_dict['connection'] + return obj_dict + + def __setstate__(self, obj_dict): + """ + Unpickling support. + """ + self.__dict__.update(obj_dict) + # XXX: Need a better solution for this when multi-db stuff is + # supported. It's the only class-reference to the module-level + # connection variable. + self.connection = connection + def get_meta(self): """ Returns the Options instance (the model._meta) from which to start diff --git a/docs/db-api.txt b/docs/db-api.txt index 6299f3497d..405ed87cef 100644 --- a/docs/db-api.txt +++ b/docs/db-api.txt @@ -376,6 +376,29 @@ You can evaluate a ``QuerySet`` in the following ways: iterating over a ``QuerySet`` will take advantage of your database to load data and instantiate objects only as you need them. + +Pickling QuerySets +~~~~~~~~~~~~~~~~~~ + +If you pickle_ a ``QuerySet``, this will also force all the results to be +loaded into memory prior to pickling. This is because pickling is usually used +as a precursor to caching and when the cached queryset is reloaded, you want +the results to already be present. This means that when you unpickle a +``QuerySet``, it contains the results at the moment it was pickled, rather +than the results that are currently in the database. + +If you only want to pickle the necessary information to recreate the +``Queryset`` from the database at a later time, pickle the ``query`` attribute +of the ``QuerySet``. You can then recreate the original ``QuerySet`` (without +any results loaded) using some code like this:: + + >>> import pickle + >>> query = pickle.loads(s) # Assuming 's' is the pickled string. + >>> qs = MyModel.objects.all() + >>> qs.query = query # Restore the original 'query'. + +.. _pickle: http://docs.python.org/lib/module-pickle.html + Limiting QuerySets ------------------ |