ashb commented on code in PR #74084: URL: https://github.com/apache/airflow/pull/74084#discussion_r4237929211
########## task-sdk/src/airflow/sdk/importers/yaml_importer/models.py: ########## @@ -0,0 +1,409 @@ +# 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. +""" +Pydantic models for the YAML/JSON DAG format. + +These are the single source of truth for the format; they validate an authored +document (rich Pydantic errors) and back the published JSON Schema. Only the +format skeleton and value grammar only is described; operator ``with:`` args, +Dag- and task-level attributes pass through untyped because the Python +constructors validate those at import time. +""" + +from __future__ import annotations + +import collections +import itertools +from typing import TYPE_CHECKING, Annotated, Any, ClassVar + +from pydantic import ( + AliasChoices, + BaseModel, + ConfigDict, + Discriminator, + Field, + RootModel, + Tag, + model_validator, +) + +if TYPE_CHECKING: + from pydantic import GetJsonSchemaHandler + from pydantic.json_schema import JsonSchemaValue + from pydantic_core import CoreSchema + +XCOM_KEYS = ("$x", "$xcom") +TEMPLATE_KEYS = ("$t", "$template") +CONST_KEY = "$const" + +# Keys deferred to a later edition... +DAG_CALLBACK_KEYS = {"on_success_callback", "on_failure_callback"} +TASK_CALLBACK_KEYS = { + "on_success_callback", + "on_failure_callback", + "on_retry_callback", + "on_execute_callback", + "on_skipped_callback", +} +TASK_ASSET_IO_KEYS = {"inlets", "outlets"} + + +class XComTarget(BaseModel): + """The object form of an XCom reference.""" + + task: str + key: str | None = None + + model_config = ConfigDict(extra="forbid") + + +class _MarkerRef(BaseModel): + """Base for a reserved ``$``-marker object.""" + + model_config = ConfigDict(extra="forbid") + + _marker_keys: ClassVar[tuple[str, ...]] + + @classmethod + def __get_pydantic_json_schema__( + cls, core_schema: CoreSchema, handler: GetJsonSchemaHandler + ) -> JsonSchemaValue: + # Emit the marker as a single key in every accepted spelling, nothing else. + schema = handler(core_schema) + (value_schema,) = schema.get("properties", {}).values() + schema["properties"] = {key: value_schema for key in cls._marker_keys} + schema.pop("required", None) + schema["oneOf"] = [{"required": [key]} for key in cls._marker_keys] + schema["additionalProperties"] = False + return schema + + +class XComRef(_MarkerRef): + """An upstream task's XCom output.""" + + _marker_keys = XCOM_KEYS + + target: str | XComTarget = Field( + serialization_alias="$x", + validation_alias=AliasChoices(*XCOM_KEYS), + ) + + +class TemplateRef(_MarkerRef): + """A Jinja template.""" + + _marker_keys = TEMPLATE_KEYS + + source: str = Field(serialization_alias="$t", validation_alias=AliasChoices(*TEMPLATE_KEYS)) + + +class ConstRef(_MarkerRef): + """Force a literal; the value is taken verbatim.""" + + _marker_keys = (CONST_KEY,) + + value: Any = Field(serialization_alias="$const", validation_alias=AliasChoices(CONST_KEY)) + + +def _value_discriminator(v: Any) -> str: + """ + Route a raw value to a marker branch, or to ``literal``. + + The prefix ``$`` is reserved to express Airflow constructs. To prevent + typos, any unknown ``$``-prefixed strings are routed here and rejected. + + If such a key is needed, it can be wrapped in ``$const``, which would + avoid this discrimator (only used by :class:`_Literal`). + """ + if isinstance(v, dict) and len(v) == 1: + (key,) = v + if key in XCOM_KEYS: + return "xcom" + if key in TEMPLATE_KEYS: + return "template" + if key == CONST_KEY: + return "const" + if isinstance(v, XComRef): + return "xcom" + if isinstance(v, TemplateRef): + return "template" + if isinstance(v, ConstRef): + return "const" + return "literal" + + +class _Literal(RootModel): + """ + A literal value. + + Containers are validated recursively so nested markers resolve; scalars pass + through. A ``$``-prefixed key here is a misused marker, so it is rejected. + """ + + root: dict[str, Value] | list[Value] | str | int | float | bool | None Review Comment: Oh, no it turns out it is part of the spec. TIL. -- This is an automated message from the Apache Git Service. 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