feat: provide detailed error on permission denied for upload

docs/changes.rst

@@ -20,6 +20,7 @@ Not yet released.
 * Added page navigation while :ref:`translating`.
 * :ref:`manage-appearance` now has distinct settings for dark mode.
 * Improved :ref:`translation-propagation` performance.
+* More detailed error messages for :http:post:`/api/translations/(string:project)/(string:component)/(string:language)/file/`.
 
 **Bug fixes**
 * Using the `has:variant` field now correctly displays strings that have variant(s) in the search language, see :ref:`search-strings`.

weblate/api/views.py

@@ -1323,8 +1323,8 @@ def file(self, request: Request, **kwargs):
             except Http404 as error:
                 raise ValidationError({"format": str(error)}) from error
 
-        if not user.has_perm("upload.perform", obj):
-            raise PermissionDenied
+        if not (can_upload := user.has_perm("upload.perform", obj)):
+            self.permission_denied(request, can_upload.reason)
 
         serializer = UploadRequestSerializer(data=request.data)
         serializer.is_valid(raise_exception=True)
@@ -1397,8 +1397,7 @@ def units(self, request: Request, **kwargs):
             serializer_class = BilingualUnitSerializer
 
         if request.method == "POST":
-            can_add = request.user.has_perm("unit.add", obj)
-            if not can_add:
+            if not (can_add := request.user.has_perm("unit.add", obj)):
                 self.permission_denied(request, can_add.reason)
             serializer = serializer_class(
                 data=request.data, context={"translation": obj}