amoghrajesh commented on code in PR #58992:
URL: https://github.com/apache/airflow/pull/58992#discussion_r2584999817
##########
airflow-core/src/airflow/api_fastapi/core_api/routes/public/xcom.py:
##########
@@ -100,16 +100,25 @@ def get_xcom_entry(
item = copy.copy(result)
if deserialize:
- # We use `airflow.serialization.serde` for deserialization here
because custom XCom backends (with their own
- # serializers/deserializers) are only used on the worker side during
task execution.
-
- # However, the XCom value is *always* stored in the metadata database
as a valid JSON object.
- # Therefore, for purposes such as UI display or returning API
responses, deserializing with
- # `airflow.serialization.serde` is safe and recommended.
- from airflow.serialization.serde import deserialize as
serde_deserialize
-
- # full=False ensures that the `item` is deserialized without loading
the classes, and it returns a stringified version
- item.value = serde_deserialize(XComModel.deserialize_value(item),
full=False)
+ # Custom XCom backends may store references (eg: object storage paths)
in the database.
+ # The custom XCom backend's deserialize_value() resolves these to
actual values, but that is only
+ # used on workers during task execution. The API reads directly from
the database and uses
+ # stringify() to convert DB values (references or serialized data) to
human readable
+ # format for UI display or for API users.
+ import json
+
+ from airflow.serialization.stringify import stringify as stringify_xcom
+
+ try:
+ parsed_value = json.loads(result.value)
+ except (ValueError, TypeError):
+ # Already deserialized (e.g., set via Task Execution API)
+ parsed_value = result.value
+
+ try:
+ item.value = stringify_xcom(parsed_value)
+ except ValueError:
Review Comment:
Thrown when an airflow class is detected. We will need task sdk installed in
order to deserialize that one
##########
airflow-core/src/airflow/serialization/stringify.py:
##########
@@ -0,0 +1,131 @@
+#
+# 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 __future__ import annotations
+
+from typing import Any, TypeVar
+
+T = TypeVar("T", bool, float, int, dict, list, str, tuple, set)
+
+CLASSNAME = "__classname__"
+VERSION = "__version__"
+DATA = "__data__"
+OLD_TYPE = "__type"
+OLD_DATA = "__var"
+OLD_DICT = "dict"
+DEFAULT_VERSION = 0
+
+_primitives = (int, bool, float, str)
+_builtin_collections = (frozenset, list, set, tuple)
+
+
+def _convert(old: dict) -> dict:
+ """Convert an old style serialization to new style."""
+ if OLD_TYPE in old and OLD_DATA in old:
+ # Return old style dicts directly as they do not need wrapping
+ if old[OLD_TYPE] == OLD_DICT:
+ return old[OLD_DATA]
+ return {CLASSNAME: old[OLD_TYPE], VERSION: DEFAULT_VERSION, DATA:
old[OLD_DATA]}
+
+ return old
+
+
+def decode(d: dict[str, Any]) -> tuple[str, int, Any]:
+ """Extract classname, version, and data from a serialized dict."""
+ classname = d[CLASSNAME]
+ version = d[VERSION]
+
+ if not isinstance(classname, str) or not isinstance(version, int):
+ raise ValueError(f"cannot decode {d!r}")
+
+ data = d.get(DATA)
+
+ return classname, version, data
+
+
+def _stringify_builtin_collection(classname: str, value: Any):
+ if classname in ("builtins.tuple", "builtins.set", "builtins.frozenset"):
+ if isinstance(value, (list, tuple, set, frozenset)):
+ items = [str(stringify(v)) for v in value]
+ return f"({','.join(items)})"
+ return None
+
+
+def stringify(o: T | None) -> object:
+ """
+ Convert a serialized object to a human readable representation.
+
+ Matches the behavior of deserialize(full=False) exactly:
+ - Returns objects as-is for primitives, collections, plain dicts
+ - Only returns string when encountering a serialized object (__classname__)
+ """
+ if o is None:
+ return o
+
+ if isinstance(o, _primitives):
+ return o
+
+ # tuples, sets are included here for backwards compatibility
+ if isinstance(o, _builtin_collections):
+ col = [stringify(d) for d in o]
+ if isinstance(o, tuple):
+ return tuple(col)
+
+ if isinstance(o, set):
+ return set(col)
+
+ return col
+
+ if not isinstance(o, dict):
+ # if o is not a dict, then it's already deserialized
+ # in this case we should return it as is
+ return o
+
+ o = _convert(o)
+
+ # plain dict and no type hint
+ if CLASSNAME not in o or VERSION not in o:
+ return {str(k): stringify(v) for k, v in o.items()}
+
+ classname, version, value = decode(o)
+
+ if not classname:
+ raise TypeError("classname cannot be empty")
+
+ # Early detection for `airflow.` classes. These classes will need full
deserialization, not just stringification
+ if isinstance(classname, str) and classname.startswith("airflow."):
+ raise ValueError(
+ f"Cannot stringify Airflow class '{classname}'. "
+ f"Use XComModel.deserialize_value() to deserialize Airflow
classes."
+ )
Review Comment:
Undecided between if I should be even more specific with `airlfow.sdk`
detection here.
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