queryset-refactor: Added a Model.from_sequence() constructor for internal and

advanced usage.


git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7474 bcc190cf-cafb-0310-a4f2-bffc1f526a37

Author: malcolmt

django/db/models/base.py

@@ -165,33 +165,6 @@ def _prepare(cls):
 class Model(object):
     __metaclass__ = ModelBase
 
-    def _get_pk_val(self, meta=None):
-        if not meta:
-            meta = self._meta
-        return getattr(self, meta.pk.attname)
-
-    def _set_pk_val(self, value):
-        return setattr(self, self._meta.pk.attname, value)
-
-    pk = property(_get_pk_val, _set_pk_val)
-
-    def __repr__(self):
-        return smart_str(u'<%s: %s>' % (self.__class__.__name__, unicode(self)))
-
-    def __str__(self):
-        if hasattr(self, '__unicode__'):
-            return force_unicode(self).encode('utf-8')
-        return '%s object' % self.__class__.__name__
-
-    def __eq__(self, other):
-        return isinstance(other, self.__class__) and self._get_pk_val() == other._get_pk_val()
-
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
-    def __hash__(self):
-        return hash(self._get_pk_val())
-
     def __init__(self, *args, **kwargs):
         dispatcher.send(signal=signals.pre_init, sender=self.__class__, args=args, kwargs=kwargs)
 
@@ -264,6 +237,59 @@ def __init__(self, *args, **kwargs):
                 raise TypeError, "'%s' is an invalid keyword argument for this function" % kwargs.keys()[0]
         dispatcher.send(signal=signals.post_init, sender=self.__class__, instance=self)
 
+    def from_sequence(cls, values):
+        """
+        An alternate class constructor, primarily for internal use.
+
+        Creates a model instance from a sequence of values (which corresponds
+        to all the non-many-to-many fields in creation order. If there are more
+        fields than values, the remaining (final) fields are given their
+        default values.
+
+        ForeignKey fields can only be initialised using id values, not
+        instances, in this method.
+        """
+        dispatcher.send(signal=signals.pre_init, sender=cls, args=values,
+                kwargs={})
+        obj = Empty()
+        obj.__class__ = cls
+        field_iter = iter(obj._meta.fields)
+        for val, field in izip(values, field_iter):
+            setattr(obj, field.attname, val)
+        for field in field_iter:
+            setattr(obj, field.attname, field.get_default())
+        dispatcher.send(signal=signals.post_init, sender=cls, instance=obj)
+        return obj
+
+    from_sequence = classmethod(from_sequence)
+
+    def __repr__(self):
+        return smart_str(u'<%s: %s>' % (self.__class__.__name__, unicode(self)))
+
+    def __str__(self):
+        if hasattr(self, '__unicode__'):
+            return force_unicode(self).encode('utf-8')
+        return '%s object' % self.__class__.__name__
+
+    def __eq__(self, other):
+        return isinstance(other, self.__class__) and self._get_pk_val() == other._get_pk_val()
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __hash__(self):
+        return hash(self._get_pk_val())
+
+    def _get_pk_val(self, meta=None):
+        if not meta:
+            meta = self._meta
+        return getattr(self, meta.pk.attname)
+
+    def _set_pk_val(self, value):
+        return setattr(self, self._meta.pk.attname, value)
+
+    pk = property(_get_pk_val, _set_pk_val)
+
     def save(self):
         """
         Save the current instance. Override this in a subclass if you want to
@@ -533,6 +559,9 @@ def get_absolute_url(opts, func, self, *args, **kwargs):
 # MISC #
 ########
 
+class Empty(object):
+    pass
+
 if sys.version_info < (2, 5):
     # Prior to Python 2.5, Exception was an old-style class
     def subclass_exception(name, parent, unused):

django/db/models/query.py

@@ -153,7 +153,7 @@ def iterator(self):
                 obj, _ = get_cached_row(self.model, row, index_start,
                         max_depth, requested=requested)
             else:
-                obj = self.model(*row[index_start:])
+                obj = self.model.from_sequence(row[index_start:])
             for i, k in enumerate(extra_select):
                 setattr(obj, k, row[i])
             yield obj
@@ -646,7 +646,7 @@ def get_cached_row(klass, row, index_start, max_depth=0, cur_depth=0,
 
     restricted = requested is not None
     index_end = index_start + len(klass._meta.fields)
-    obj = klass(*row[index_start:index_end])
+    obj = klass.from_sequence(row[index_start:index_end])
     for f in klass._meta.fields:
         if (not f.rel or (not restricted and f.null) or
                 (restricted and f.name not in requested) or f.rel.parent_link):