Remove 'PatchRelationSerializer'

This wasn't writeable for reasons I haven't been able to figure out.
However, it's not actually needed: the 'PatchSerializer' can do the job
just fine, given enough information. This exposes a bug in DRF, which
has been reported upstream [1]. While we wait for that fix, or some
variant of it, to be merged, we must monkey patch the library.

[1] https://github.com/encode/django-rest-framework/issues/7550
[2] https://github.com/encode/django-rest-framework/pull/7574

Signed-off-by: Stephen Finucane <stephen@that.guru>
Reported-by: Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de>
Closes: #379
Cc: Daniel Axtens <dja@axtens.net>
Cc: Rohit Sarkar <rohitsarkar5398@gmail.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/patchwork/api/__init__.py b/patchwork/api/__init__.py
index e69de29..efc0dd8 100644
--- a/patchwork/api/__init__.py
+++ b/patchwork/api/__init__.py
@@ -0,0 +1,50 @@
+# Patchwork - automated patch tracking system
+# Copyright (C) 2020, Stephen Finucane <stephen@that.guru>
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+from rest_framework.fields import empty
+from rest_framework.fields import get_attribute
+from rest_framework.fields import SkipField
+from rest_framework.relations import ManyRelatedField
+
+
+# monkey patch django-rest-framework to work around issue #7550 [1] until #7574
+# [2] or some other variant lands
+#
+# [1] https://github.com/encode/django-rest-framework/issues/7550
+# [2] https://github.com/encode/django-rest-framework/pull/7574
+
+def _get_attribute(self, instance):
+    # Can't have any relationships if not created
+    if hasattr(instance, 'pk') and instance.pk is None:
+        return []
+
+    try:
+        relationship = get_attribute(instance, self.source_attrs)
+    except (KeyError, AttributeError) as exc:
+        if self.default is not empty:
+            return self.get_default()
+        if self.allow_null:
+            return None
+        if not self.required:
+            raise SkipField()
+        msg = (
+            'Got {exc_type} when attempting to get a value for field '
+            '`{field}` on serializer `{serializer}`.\nThe serializer '
+            'field might be named incorrectly and not match '
+            'any attribute or key on the `{instance}` instance.\n'
+            'Original exception text was: {exc}.'.format(
+                exc_type=type(exc).__name__,
+                field=self.field_name,
+                serializer=self.parent.__class__.__name__,
+                instance=instance.__class__.__name__,
+                exc=exc
+            )
+        )
+        raise type(exc)(msg)
+
+    return relationship.all() if hasattr(relationship, 'all') else relationship
+
+
+ManyRelatedField.get_attribute = _get_attribute