Do not check schema name/version if no catalog

CHANGELOG.md

@@ -7,7 +7,7 @@
   - Organization can nom define a custom metadata of a choosen type
   - Dataset belonging to the organization can assign a value to the defined metadata
   - Metadata value must match the choosen type by the organization
-- Harvest DCAT conformsTo into schemas for resources and datasets
+- Harvest DCAT conformsTo into schemas for resources and datasets[#2949](https://github.com/opendatateam/udata/pull/2949) [#2970](https://github.com/opendatateam/udata/pull/2970)
 - Better reporting in spam detection (show the writer of the discussion/message) [#2965](https://github.com/opendatateam/udata/pull/2965)
 - Fix: spam lang detection not lowering input resulting in false positives [#2965](https://github.com/opendatateam/udata/pull/2965)
 - Fix: do not send mail about discussions when there is no owner / no organisation members [#2962](https://github.com/opendatateam/udata/pull/2962)

udata/core/dataset/models.py

@@ -192,13 +192,21 @@ def clean(self):
             # Nothing more to do since an URL can point to anywhere and have a random name/version
             return
 
+        # All the following checks are only run if there is 
+        # some schemas in the catalog. If there is no catalog
+        # or no schema in the catalog we do not check the validity
+        # of the name and version
+        catalog_schemas = ResourceSchema.all()
+        if not catalog_schemas:
+            return
+
         # We know this schema so we can do some checks
         existing_schema = ResourceSchema.get_schema_by_name(self.name)
         if not existing_schema:
             message = _('Schema name "{schema}" is not an allowed value. Allowed values: {values}')
             raise FieldValidationError(message.format(
                 schema=self.name,
-                values=', '.join(map(lambda schema: schema['name'], ResourceSchema.all()))
+                values=', '.join(map(lambda schema: schema['name'], catalog_schemas))
             ), field='name')
 
         if self.version: