feat: add export_related flag (#19215)

* feat: add export_related flag

* Fix lint

superset/commands/export/models.py

@@ -0,0 +1,68 @@
+# 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.
+
+from datetime import datetime, timezone
+from typing import Iterator, List, Tuple, Type
+
+import yaml
+from flask_appbuilder import Model
+
+from superset.commands.base import BaseCommand
+from superset.commands.exceptions import CommandException
+from superset.dao.base import BaseDAO
+from superset.utils.dict_import_export import EXPORT_VERSION
+
+METADATA_FILE_NAME = "metadata.yaml"
+
+
+class ExportModelsCommand(BaseCommand):
+
+    dao: Type[BaseDAO] = BaseDAO
+    not_found: Type[CommandException] = CommandException
+
+    def __init__(self, model_ids: List[int], export_related: bool = True):
+        self.model_ids = model_ids
+        self.export_related = export_related
+
+        # this will be set when calling validate()
+        self._models: List[Model] = []
+
+    @staticmethod
+    def _export(model: Model, export_related: bool = True) -> Iterator[Tuple[str, str]]:
+        raise NotImplementedError("Subclasses MUST implement _export")
+
+    def run(self) -> Iterator[Tuple[str, str]]:
+        self.validate()
+
+        metadata = {
+            "version": EXPORT_VERSION,
+            "type": self.dao.model_cls.__name__,  # type: ignore
+            "timestamp": datetime.now(tz=timezone.utc).isoformat(),
+        }
+        yield METADATA_FILE_NAME, yaml.safe_dump(metadata, sort_keys=False)
+
+        seen = {METADATA_FILE_NAME}
+        for model in self._models:
+            for file_name, file_content in self._export(model, self.export_related):
+                if file_name not in seen:
+                    yield file_name, file_content
+                    seen.add(file_name)
+
+    def validate(self) -> None:
+        self._models = self.dao.find_by_ids(self.model_ids)
+        if len(self._models) != len(self.model_ids):
+            raise self.not_found()