feat(model): res position unique index;

- Create a unique index for active resource positions.

Author: JVickery-TBS

ckan/migration/versions/109_e12e991f586b_create_res_position_index.py

@@ -0,0 +1,29 @@
+"""empty message
+
+Revision ID: e12e991f586b
+Revises: f7b64c701a10
+Create Date: 2026-02-10 18:26:31.122945
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'e12e991f586b'
+down_revision = 'f7b64c701a10'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_index(
+        "idx_package_resource_unique_position", "resource",
+        [sa.Column('package_id'), sa.Column('position')],
+        unique=True, postgresql_where=sa.text('"resource".state=\'active\''))
+    print('Created "idx_package_resource_unique_position" index')
+
+
+def downgrade():
+    op.drop_index("idx_package_resource_unique_position")
+    print('Dropped "idx_package_resource_unique_position" index')

ckan/model/resource.py

@@ -59,6 +59,9 @@
     Index('idx_package_resource_id', 'id'),
     Index('idx_package_resource_package_id', 'package_id'),
     Index('idx_package_resource_url', 'url'),
+    Index('idx_package_resource_unique_position',
+          Column('package_id'), Column('position'),
+          unique=True, postgresql_where="(state = 'active'::text)")
 )
 
 

ckan/tests/model/test_resource.py

@@ -1,6 +1,7 @@
 # encoding: utf-8
 
 import pytest
+from sqlalchemy.exc import IntegrityError
 
 import ckan.model as model
 import ckan.tests.factories as factories
@@ -60,3 +61,20 @@ def test_package_purge_deletes_resources(self):
         model.repo.commit_and_remove()
 
         assert model.Resource.active().count() == initial
+
+    def test_resource_unique_positions(self):
+        """
+        Position values should be unique per dataset.
+        """
+        parent = factories.Dataset()
+        factories.Resource(package_id=parent["id"])
+        res2 = factories.Resource(package_id=parent["id"])
+
+        res2.position = 0
+
+        with pytest.raises(IntegrityError) as e:
+            model.Session.add(res2)
+            model.Session.commit()
+
+        err = e.value
+        assert 'duplicate key value violates unique constraint "idx_package_resource_unique_position"' in str(err)