Fix queryset assigment, should always be of MetadataType not DocumentTypeMetadataType, errors out on Postgres.

mayan/apps/metadata/forms.py

@@ -101,7 +101,11 @@ class AddMetadataForm(forms.Form):
     def __init__(self, *args, **kwargs):
         document_type = kwargs.pop('document_type')
         super(AddMetadataForm, self).__init__(*args, **kwargs)
-        self.fields['metadata_type'].queryset = document_type.metadata.all()
+        self.fields['metadata_type'].queryset = MetadataType.objects.filter(
+            pk__in=document_type.metadata.values_list(
+                'metadata_type', flat=True
+            )
+        )
 
 
 class MetadataTypeForm(forms.ModelForm):

mayan/apps/metadata/views.py

@@ -243,7 +243,7 @@ def metadata_add(request, document_id=None, document_id_list=None):
                 try:
                     document_metadata, created = DocumentMetadata.objects.get_or_create(
                         document=document,
-                        metadata_type=metadata_type.metadata_type,
+                        metadata_type=metadata_type,
                         defaults={'value': ''}
                     )
                 except Exception as exception: