[dashboards] Fix, API update slug uniqueness refusing empty string (#9417)

* [dashboards] Fix, API update slug uniqueness refusing empty string

* [dashboards] tests

superset/dashboards/commands/update.py

@@ -57,7 +57,7 @@ class UpdateDashboardCommand(BaseCommand):
     def validate(self) -> None:
         exceptions: List[ValidationError] = []
         owner_ids: Optional[List[int]] = self._properties.get("owners")
-        slug: str = self._properties.get("slug", "")
+        slug: Optional[str] = self._properties.get("slug")
 
         # Validate/populate model exists
         self._model = DashboardDAO.find_by_id(self._model_id)

superset/dashboards/dao.py

@@ -15,7 +15,7 @@
 # specific language governing permissions and limitations
 # under the License.
 import logging
-from typing import List
+from typing import List, Optional
 
 from sqlalchemy.exc import SQLAlchemyError
 
@@ -39,11 +39,13 @@ class DashboardDAO(BaseDAO):
         return not db.session.query(dashboard_query.exists()).scalar()
 
     @staticmethod
-    def validate_update_slug_uniqueness(dashboard_id: int, slug: str) -> bool:
-        dashboard_query = db.session.query(Dashboard).filter(
-            Dashboard.slug == slug, Dashboard.id != dashboard_id
-        )
-        return not db.session.query(dashboard_query.exists()).scalar()
+    def validate_update_slug_uniqueness(dashboard_id: int, slug: Optional[str]) -> bool:
+        if slug is not None:
+            dashboard_query = db.session.query(Dashboard).filter(
+                Dashboard.slug == slug, Dashboard.id != dashboard_id
+            )
+            return not db.session.query(dashboard_query.exists()).scalar()
+        return True
 
     @staticmethod
     def bulk_delete(models: List[Dashboard], commit=True):

tests/dashboards/api_tests.py

@@ -50,7 +50,7 @@ class DashboardApiTests(SupersetTestCase, ApiOwnersTestCaseMixin):
     def insert_dashboard(
         self,
         dashboard_title: str,
-        slug: str,
+        slug: Optional[str],
         owners: List[int],
         slices: Optional[List[Slice]] = None,
         position_json: str = "",
@@ -647,6 +647,19 @@ class DashboardApiTests(SupersetTestCase, ApiOwnersTestCaseMixin):
         db.session.delete(dashboard2)
         db.session.commit()
 
+        dashboard1 = self.insert_dashboard("title1", None, [admin_id])
+        dashboard2 = self.insert_dashboard("title2", None, [admin_id])
+        self.login(username="admin")
+        # Accept empty slugs and don't validate them has unique
+        dashboard_data = {"dashboard_title": "title2_changed", "slug": ""}
+        uri = f"api/v1/dashboard/{dashboard2.id}"
+        rv = self.client.put(uri, json=dashboard_data)
+        self.assertEqual(rv.status_code, 200)
+
+        db.session.delete(dashboard1)
+        db.session.delete(dashboard2)
+        db.session.commit()
+
     def test_update_published(self):
         """
             Dashboard API: Test update published patch