fix(dashboard): increase json_metadata field (apache#24510)

superset/migrations/versions/2023-06-28_19-49_bf646a0c1501_json_metadata.py

@@ -0,0 +1,53 @@
+# 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.
+"""json_metadata
+
+Revision ID: bf646a0c1501
+Revises: a23c6f8b1280
+Create Date: 2023-06-28 19:49:59.217255
+
+"""
+
+
+import sqlalchemy as sa
+from alembic import op
+
+from superset.utils.core import MediumText
+
+# revision identifiers, used by Alembic.
+revision = "bf646a0c1501"
+down_revision = "a23c6f8b1280"
+
+
+def upgrade():
+    with op.batch_alter_table("dashboards") as batch_op:
+        batch_op.alter_column(
+            "json_metadata",
+            existing_type=sa.Text(),
+            type_=MediumText(),
+            existing_nullable=True,
+        )
+
+
+def downgrade():
+    with op.batch_alter_table("dashboards") as batch_op:
+        batch_op.alter_column(
+            "json_metadata",
+            existing_type=MediumText(),
+            type_=sa.Text(),
+            existing_nullable=True,
+        )

superset/models/dashboard.py

@@ -141,7 +141,7 @@ class Dashboard(Model, AuditMixinNullable, ImportExportMixin):
     css = Column(Text)
     certified_by = Column(Text)
     certification_details = Column(Text)
-    json_metadata = Column(Text)
+    json_metadata = Column(utils.MediumText())
     slug = Column(String(255), unique=True)
     slices: list[Slice] = relationship(
         Slice, secondary=dashboard_slices, backref="dashboards"