fix: RLS new db migration downgrade fails on SQLite (#20449)

superset/migrations/versions/2022-06-19_16-17_f3afaf1f11f0_add_unique_name_desc_rls.py

@@ -0,0 +1,78 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+"""add_unique_name_desc_rls
+
+Revision ID: f3afaf1f11f0
+Revises: e786798587de
+Create Date: 2022-06-19 16:17:23.318618
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = "f3afaf1f11f0"
+down_revision = "e786798587de"
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import Session
+
+Base = declarative_base()
+
+
+class RowLevelSecurityFilter(Base):
+    __tablename__ = "row_level_security_filters"
+    id = sa.Column(sa.Integer, primary_key=True)
+    name = sa.Column(sa.String(255), unique=True, nullable=False)
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    bind = op.get_bind()
+    session = Session(bind=bind)
+
+    op.add_column(
+        "row_level_security_filters", sa.Column("name", sa.String(length=255))
+    )
+    op.add_column(
+        "row_level_security_filters", sa.Column("description", sa.Text(), nullable=True)
+    )
+
+    # Set initial default names make sure we can have unique non null values
+    all_rls = session.query(RowLevelSecurityFilter).all()
+    for rls in all_rls:
+        rls.name = f"rls-{rls.id}"
+    session.commit()
+
+    # Now it's safe so set non-null and unique
+    # add unique constraint
+    with op.batch_alter_table("row_level_security_filters") as batch_op:
+        # batch mode is required for sqlite
+        batch_op.alter_column(
+            "name",
+            existing_type=sa.String(255),
+            nullable=False,
+        )
+        batch_op.create_unique_constraint("uq_rls_name", ["name"])
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    with op.batch_alter_table("row_level_security_filters") as batch_op:
+        batch_op.drop_constraint("uq_rls_name", type_="unique")
+        batch_op.drop_column("description")
+        batch_op.drop_column("name")