Fixed #736 -- Changed behavior of QueryDict items() to be more consistent, fixed mutability holes, gave MultiValueDict many more dictionary methods and added unit tests. Thanks, Kieran Holland. This is slightly backwards-incompatible if you happened to rely on the behavior of QueryDict.items(), which is highly unlikely.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@1504 bcc190cf-cafb-0310-a4f2-bffc1f526a37

4 files changed, 109 insertions, 103 deletions

diff --git a/django/contrib/admin/views/main.py b/django/contrib/admin/views/main.py
index 0cb9dccb26..8a13433613 100644
--- a/django/contrib/admin/views/main.py
+++ b/django/contrib/admin/views/main.py
@@ -57,7 +57,7 @@ class ChangeList(object):
         self.get_modules_and_options(app_label, module_name, request)
         self.get_search_parameters(request)
         self.get_ordering()
-        self.query = request.GET.get(SEARCH_VAR,'')
+        self.query = request.GET.get(SEARCH_VAR, '')
         self.get_lookup_params()
         self.get_results(request)
         self.title = (self.is_popup
@@ -100,13 +100,12 @@ class ChangeList(object):
     def get_search_parameters(self, request):
         # Get search parameters from the query string.
         try:
-            self.req_get = request.GET
             self.page_num = int(request.GET.get(PAGE_VAR, 0))
         except ValueError:
             self.page_num = 0
         self.show_all = request.GET.has_key(ALL_VAR)
         self.is_popup = request.GET.has_key(IS_POPUP_VAR)
-        self.params = dict(request.GET.copy())
+        self.params = dict((k, v) for k, v in request.GET.items())
         if self.params.has_key(PAGE_VAR):
             del self.params[PAGE_VAR]
 
diff --git a/django/core/meta/__init__.py b/django/core/meta/__init__.py
index eb83545897..8b760dced7 100644
--- a/django/core/meta/__init__.py
+++ b/django/core/meta/__init__.py
@@ -1678,7 +1678,6 @@ def manipulator_save(opts, klass, add, change, self, new_data):
                 param = f.get_default()
         params[f.attname] = param
 
-
     if change:
         params[opts.pk.attname] = self.obj_key
 
@@ -1710,7 +1709,7 @@ def manipulator_save(opts, klass, add, change, self, new_data):
                 if change and was_changed:
                     self.fields_changed.append(f.verbose_name)
 
-    expanded_data = DotExpandedDict(new_data.data)
+    expanded_data = DotExpandedDict(dict(new_data))
     # Save many-to-one objects. Example: Add the Choice objects for a Poll.
     for related in opts.get_all_related_objects():
         # Create obj_list, which is a DotExpandedDict such as this:
@@ -1724,7 +1723,6 @@ def manipulator_save(opts, klass, add, change, self, new_data):
             obj_list.sort(lambda x, y: cmp(int(x[0]), int(y[0])))
             params = {}
 
-
             # For each related item...
             for _, rel_new_data in obj_list:
 
@@ -1769,7 +1767,6 @@ def manipulator_save(opts, klass, add, change, self, new_data):
                     if param != None:
                        params[f.attname] = param
 
-
                     # Related links are a special case, because we have to
                     # manually set the "content_type_id" and "object_id" fields.
                     if opts.has_related_links and related.opts.module_name == 'relatedlinks':
@@ -1780,8 +1777,6 @@ def manipulator_save(opts, klass, add, change, self, new_data):
                 # Create the related item.
                 new_rel_obj = related.opts.get_model_module().Klass(**params)
 
-
-
                 # If all the core fields were provided (non-empty), save the item.
                 if all_cores_given:
                     new_rel_obj.save()
@@ -1814,7 +1809,6 @@ def manipulator_save(opts, klass, add, change, self, new_data):
                     new_rel_obj.delete()
                     self.fields_deleted.append('%s "%s"' % (related.opts.verbose_name, old_rel_obj))
 
-
     # Save the order, if applicable.
     if change and opts.get_ordered_objects():
         order = new_data['order_'] and map(int, new_data['order_'].split(',')) or []
diff --git a/django/utils/datastructures.py b/django/utils/datastructures.py
index 2779e2ae00..81e4b30f6e 100644
--- a/django/utils/datastructures.py
+++ b/django/utils/datastructures.py
@@ -43,9 +43,9 @@ class MergeDict:
 class MultiValueDictKeyError(KeyError):
     pass
 
-class MultiValueDict:
+class MultiValueDict(dict):
     """
-    A dictionary-like class customized to deal with multiple values for the same key.
+    A subclass of dictionary customized to handle multiple values for the same key.
 
     >>> d = MultiValueDict({'name': ['Adrian', 'Simon'], 'position': ['Developer']})
     >>> d['name']
@@ -60,35 +60,32 @@ class MultiValueDict:
     which returns a list for every key, even though most Web forms submit
     single name-value pairs.
     """
-    def __init__(self, key_to_list_mapping=None):
-        self.data = key_to_list_mapping or {}
-
-    def __repr__(self):
-        return repr(self.data)
+    def __init__(self, key_to_list_mapping=()):
+        dict.__init__(self, key_to_list_mapping)
 
     def __getitem__(self, key):
-        "Returns the data value for this key; raises KeyError if not found"
-        if self.data.has_key(key):
-            try:
-                return self.data[key][-1] # in case of duplicates, use last value ([-1])
-            except IndexError:
-                return []
-        raise MultiValueDictKeyError, "Key '%s' not found in MultiValueDict %s" % (key, self.data)
-
-    def __setitem__(self, key, value):
-        self.data[key] = [value]
-
-    def __len__(self):
-        return len(self.data)
+        """
+        Returns the last data value for this key, or [] if it's an empty list;
+        raises KeyError if not found.
+        """
+        try:
+            list_ = dict.__getitem__(self, key)
+        except KeyError:
+            raise MultiValueDictKeyError, "Key %r not found in MultiValueDict %r" % (key, self)
+        try:
+            return list_[-1]
+        except IndexError:
+            return []
 
-    def __contains__(self, key):
-        return self.data.has_key(key)
+    def _setitem_list(self, key, value):
+        dict.__setitem__(self, key, [value])
+    __setitem__ = _setitem_list
 
-    def get(self, key, default):
+    def get(self, key, default=None):
         "Returns the default value if the requested data doesn't exist"
         try:
             val = self[key]
-        except (KeyError, IndexError):
+        except KeyError:
             return default
         if val == []:
             return default
@@ -97,47 +94,64 @@ class MultiValueDict:
     def getlist(self, key):
         "Returns an empty list if the requested data doesn't exist"
         try:
-            return self.data[key]
+            return dict.__getitem__(self, key)
         except KeyError:
             return []
 
     def setlist(self, key, list_):
-        self.data[key] = list_
+        dict.__setitem__(self, key, list_)
 
-    def appendlist(self, key, item):
-        "Appends an item to the internal list associated with key"
-        try:
-            self.data[key].append(item)
-        except KeyError:
-            self.data[key] = [item]
+    def setdefault(self, key, default=None):
+        if key not in self:
+            self[key] = default
+        return self[key]
 
-    def has_key(self, key):
-        return self.data.has_key(key)
+    def setlistdefault(self, key, default_list=()):
+        if key not in self:
+            self.setlist(key, default_list)
+        return self.getlist(key)
+
+    def appendlist(self, key, value):
+        "Appends an item to the internal list associated with key"
+        self.setlistdefault(key, [])
+        dict.__setitem__(self, key, self.getlist(key) + [value])
 
     def items(self):
-        # we don't just return self.data.items() here, because we want to use
-        # self.__getitem__() to access the values as *strings*, not lists
-        return [(key, self[key]) for key in self.data.keys()]
+        """
+        Returns a list of (key, value) pairs, where value is the last item in
+        the list associated with the key.
+        """
+        return [(key, self[key]) for key in self.keys()]
 
-    def keys(self):
-        return self.data.keys()
+    def lists(self):
+        "Returns a list of (key, list) pairs."
+        return dict.items(self)
 
-    def update(self, other_dict):
-        if isinstance(other_dict, MultiValueDict):
-            for key, value_list in other_dict.data.items():
-                self.data.setdefault(key, []).extend(value_list)
-        elif type(other_dict) == type({}):
-            for key, value in other_dict.items():
-                self.data.setdefault(key, []).append(value)
-        else:
-            raise ValueError, "MultiValueDict.update() takes either a MultiValueDict or dictionary"
+    def values(self):
+        "Returns a list of the last value on every key list."
+        return [self[key] for key in self.keys()]
 
     def copy(self):
-        "Returns a copy of this object"
+        "Returns a copy of this object."
         import copy
+        # Our custom __setitem__ must be disabled for copying machinery.
+        MultiValueDict.__setitem__ = dict.__setitem__
         cp = copy.deepcopy(self)
+        MultiValueDict.__setitem__ = MultiValueDict._setitem_list
         return cp
 
+    def update(self, other_dict):
+        "update() extends rather than replaces existing key lists."
+        if isinstance(other_dict, MultiValueDict):
+            for key, value_list in other_dict.lists():
+                self.setlistdefault(key, []).extend(value_list)
+        else:
+            try:
+                for key, value in other_dict.items():
+                    self.setlistdefault(key, []).append(value)
+            except TypeError:
+                raise ValueError, "MultiValueDict.update() takes either a MultiValueDict or dictionary"
+
 class DotExpandedDict(dict):
     """
     A special dictionary constructor that takes a dictionary in which the keys
diff --git a/django/utils/httpwrappers.py b/django/utils/httpwrappers.py
index 305ef51607..32f2bfb8f7 100644
--- a/django/utils/httpwrappers.py
+++ b/django/utils/httpwrappers.py
@@ -67,63 +67,62 @@ class QueryDict(MultiValueDict):
     """A specialized MultiValueDict that takes a query string when initialized.
     This is immutable unless you create a copy of it."""
     def __init__(self, query_string):
-        if not query_string:
-            self.data = {}
-            self._keys = []
-        else:
-            self.data = {}
-            self._keys = []
-            for name, value in parse_qsl(query_string, True): # keep_blank_values=True
-                if name in self.data:
-                    self.data[name].append(value)
-                else:
-                    self.data[name] = [value]
-                if name not in self._keys:
-                    self._keys.append(name)
+        MultiValueDict.__init__(self)
+        self._mutable = True
+        for key, value in parse_qsl(query_string, True): # keep_blank_values=True
+            self.appendlist(key, value)
         self._mutable = False
 
-    def __setitem__(self, key, value):
+    def _assert_mutable(self):
         if not self._mutable:
             raise AttributeError, "This QueryDict instance is immutable"
-        else:
-            self.data[key] = [value]
-            if not key in self._keys:
-                self._keys.append(key)
+
+    def _setitem_if_mutable(self, key, value):
+        self._assert_mutable()
+        MultiValueDict.__setitem__(self, key, value)
+    __setitem__ = _setitem_if_mutable
 
     def setlist(self, key, list_):
-        if not self._mutable:
-            raise AttributeError, "This QueryDict instance is immutable"
-        else:
-            self.data[key] = list_
-            if not key in self._keys:
-                self._keys.append(key)
+        self._assert_mutable()
+        MultiValueDict.setlist(self, key, list_)
 
-    def copy(self):
-        "Returns a mutable copy of this object"
-        cp = MultiValueDict.copy(self)
-        cp._mutable = True
-        return cp
+    def appendlist(self, key, value):
+        self._assert_mutable()
+        MultiValueDict.appendlist(self, key, value)
 
-    def assert_synchronized(self):
-        assert(len(self._keys) == len(self.data.keys())), \
-            "QueryDict data structure is out of sync: %s %s" % (str(self._keys), str(self.data))
+    def update(self, other_dict):
+        self._assert_mutable()
+        MultiValueDict.update(self, other_dict)
 
-    def items(self):
-        "Respect order preserved by self._keys"
-        self.assert_synchronized()
-        items = []
-        for key in self._keys:
-            if key in self.data:
-                items.append((key, self.data[key][0]))
-        return items
+    def pop(self, key):
+        self._assert_mutable()
+        return MultiValueDict.pop(self, key)
 
-    def keys(self):
-        self.assert_synchronized()
-        return self._keys
+    def popitem(self):
+        self._assert_mutable()
+        return MultiValueDict.popitem(self)
+
+    def clear(self):
+        self._assert_mutable()
+        MultiValueDict.clear(self)
+
+    def setdefault(self, *args):
+        self._assert_mutable()
+        return MultiValueDict.setdefault(self, *args)
+
+    def copy(self):
+        "Returns a mutable copy of this object."
+        import copy
+        # Our custom __setitem__ must be disabled for copying machinery.
+        QueryDict.__setitem__ = dict.__setitem__
+        cp = copy.deepcopy(self)
+        QueryDict.__setitem__ = QueryDict._setitem_if_mutable
+        cp._mutable = True
+        return cp
 
     def urlencode(self):
         output = []
-        for k, list_ in self.data.items():
+        for k, list_ in self.lists():
             output.extend([urlencode({k: v}) for v in list_])
         return '&'.join(output)