Refactored the way save() works so that non-integer primary keys are …

…now possible. custom_pk unit tests (from [458]) now pass. Refs #81.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@462 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/meta/__init__.py

@@ -208,6 +208,14 @@ def __init__(self, module_name='', verbose_name='', verbose_name_plural='', db_t
         if self.pk is None:
             self.fields.insert(0, AutoField('id', 'ID', primary_key=True))
             self.pk = self.fields[0]
+        # Cache whether this has an AutoField.
+        self.has_auto_field = False
+        for f in self.fields:
+            is_auto = isinstance(f, AutoField)
+            if is_auto and self.has_auto_field:
+                raise AssertionError, "A model can't have more than one AutoField."
+            elif is_auto:
+                self.has_auto_field = True
 
     def __repr__(self):
         return '<Options for %s>' % self.module_name
@@ -717,37 +725,27 @@ def method_save(opts, self):
         self._pre_save()
     non_pks = [f for f in opts.fields if not f.primary_key]
     cursor = db.db.cursor()
-    add = not bool(getattr(self, opts.pk.name))
-    for f in non_pks:
-        f.pre_save(self, getattr(self, f.name), add)
-    db_values = [f.get_db_prep_save(getattr(self, f.name)) for f in non_pks]
-    # OneToOne objects are a special case because there's no AutoField, and the
-    # primary key field is set manually.
-    if isinstance(opts.pk.rel, OneToOne):
-        cursor.execute("UPDATE %s SET %s WHERE %s=%%s" % \
-            (opts.db_table, ','.join(['%s=%%s' % f.name for f in non_pks]),
-            opts.pk.name), db_values + [getattr(self, opts.pk.name)])
-        if cursor.rowcount == 0: # If nothing was updated, add the record.
-            field_names = [f.name for f in opts.fields]
-            placeholders = ['%s'] * len(field_names)
-            cursor.execute("INSERT INTO %s (%s) VALUES (%s)" % \
-                (opts.db_table, ','.join(field_names), ','.join(placeholders)),
-                [f.get_db_prep_save(getattr(self, f.name)) for f in opts.fields])
-    else:
-        if not add:
-            cursor.execute("UPDATE %s SET %s WHERE %s=%%s" % \
-                (opts.db_table, ','.join(['%s=%%s' % f.name for f in non_pks]),
-                opts.pk.name), db_values + [getattr(self, opts.pk.name)])
-        else:
-            field_names = [f.name for f in non_pks]
-            placeholders = ['%s'] * len(field_names)
-            if opts.order_with_respect_to:
-                field_names.append('_order')
-                placeholders.append('(SELECT COUNT(*) FROM %s WHERE %s = %%s)' % \
-                    (opts.db_table, opts.order_with_respect_to.name))
-                db_values.append(getattr(self, opts.order_with_respect_to.name))
-            cursor.execute("INSERT INTO %s (%s) VALUES (%s)" % \
-                (opts.db_table, ','.join(field_names), ','.join(placeholders)), db_values)
+
+    # First, try an UPDATE. If that doesn't update anything, do an INSERT.
+    pk_set = bool(getattr(self, opts.pk.name))
+    if pk_set:
+        db_values = [f.get_db_prep_save(f.pre_save(getattr(self, f.name), False)) for f in non_pks]
+        cursor.execute("UPDATE %s SET %s WHERE %s=%%s" % (opts.db_table,
+            ','.join(['%s=%%s' % f.name for f in non_pks]), opts.pk.name),
+            db_values + [getattr(self, opts.pk.name)])
+    if not pk_set or cursor.rowcount == 0:
+        field_names = [f.name for f in opts.fields if not isinstance(f, AutoField)]
+        placeholders = ['%s'] * len(field_names)
+        db_values = [f.get_db_prep_save(f.pre_save(getattr(self, f.name), True)) for f in opts.fields if not isinstance(f, AutoField)]
+        if opts.order_with_respect_to:
+            field_names.append('_order')
+            # TODO: This assumes the database supports subqueries.
+            placeholders.append('(SELECT COUNT(*) FROM %s WHERE %s = %%s)' % \
+                (opts.db_table, opts.order_with_respect_to.name))
+            db_values.append(getattr(self, opts.order_with_respect_to.name))
+        cursor.execute("INSERT INTO %s (%s) VALUES (%s)" % (opts.db_table,
+            ','.join(field_names), ','.join(placeholders)), db_values)
+        if opts.has_auto_field:
             setattr(self, opts.pk.name, db.get_last_insert_id(cursor, opts.db_table, opts.pk.name))
     db.db.commit()
     # Run any post-save hooks.

django/core/meta/fields.py

@@ -82,12 +82,9 @@ def __init__(self, name, verbose_name=None, primary_key=False,
         else:
             self.db_index = db_index
 
-    def pre_save(self, obj, value, add):
-        """
-        Hook for altering the object obj based on the value of this field and
-        and on the add/change status.
-        """
-        pass
+    def pre_save(self, value, add):
+        "Returns field's value just before saving."
+        return value
 
     def get_db_prep_save(self, value):
         "Returns field's value prepared for saving into a database."
@@ -236,6 +233,10 @@ def get_choices(self, include_blank=True, blank_choice=BLANK_CHOICE_DASH):
 
 class AutoField(Field):
     empty_strings_allowed = False
+    def __init__(self, *args, **kwargs):
+        assert kwargs.get('primary_key', False) is True, "%ss must have primary_key=True." % self.__class__.__name__
+        Field.__init__(self, *args, **kwargs)
+
     def get_manipulator_fields(self, opts, manipulator, change, name_prefix='', rel=False):
         if not rel:
             return [] # Don't add a FormField unless it's in a related context.
@@ -280,9 +281,10 @@ def get_db_prep_lookup(self, lookup_type, value):
             value = str(value)
         return Field.get_db_prep_lookup(self, lookup_type, value)
 
-    def pre_save(self, obj, value, add):
+    def pre_save(self, value, add):
         if self.auto_now or (self.auto_now_add and add):
-            setattr(obj, self.name, datetime.datetime.now())
+            return datetime.datetime.now()
+        return value
 
     def get_db_prep_save(self, value):
         # Casts dates into string format for entry into database.
@@ -483,9 +485,10 @@ def get_db_prep_lookup(self, lookup_type, value):
             value = str(value)
         return Field.get_db_prep_lookup(self, lookup_type, value)
 
-    def pre_save(self, obj, value, add):
+    def pre_save(self, value, add):
         if self.auto_now or (self.auto_now_add and add):
-            setattr(obj, self.name, datetime.datetime.now().time())
+            return datetime.datetime.now().time()
+        return value
 
     def get_db_prep_save(self, value):
         # Casts dates into string format for entry into database.