Add radio button rendering for enum Dag Params

airflow-core/docs/core-concepts/params.rst

@@ -253,6 +253,11 @@ The following features are supported in the Trigger UI Form:
             * ``format="multiline"``: Generate a multi-line textarea
             * | ``enum=["a", "b", "c"]``: Generates a
               | drop-down select list for scalar values.
+              | If the choices come from an external config file,
+              | read that file while the Dag is parsed and pass the
+              | resulting list to ``enum``; the trigger form reads
+              | the serialized Dag Params and does not call dynamic
+              | choice providers when the form opens.
               | As of JSON validation, a value must be
               | selected or the field must be marked as
               | optional explicit. See also details inside

airflow-core/newsfragments/71180.improvement.rst

@@ -0,0 +1 @@
+Documented how to populate enum Dag Params from external config files for the trigger Dag form.

airflow-core/src/airflow/example_dags/example_params_ui_interfaces.ini

@@ -0,0 +1,25 @@
+# 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.
+
+[InterfaceA]
+TYPE = Script
+
+[InterfaceB]
+TYPE = EBICS
+
+[InterfaceC]
+TYPE = Script

airflow-core/src/airflow/example_dags/example_params_ui_tutorial.py

@@ -23,12 +23,23 @@
 
 from __future__ import annotations
 
+import configparser
 import datetime
 import json
 from pathlib import Path
 
 from airflow.sdk import DAG, Param, task
 
+
+def _get_script_interfaces_from_config() -> list[str]:
+    config = configparser.ConfigParser()
+    config.read(Path(__file__).with_name("example_params_ui_interfaces.ini"))
+
+    return [section for section in config.sections() if config[section].get("TYPE") == "Script"]
+
+
+SCRIPT_INTERFACES = _get_script_interfaces_from_config()
+
 with DAG(
     dag_id=Path(__file__).stem,
     dag_display_name="Params UI tutorial",
@@ -75,6 +86,19 @@
             enum=[f"value {i}" for i in range(16, 64)],
             section="Typed parameters with Param object",
         ),
+        "script_interface": Param(
+            SCRIPT_INTERFACES[0],
+            schema={
+                "type": "string",
+                "title": "Script interface",
+                "description": "Choices are generated from example_params_ui_interfaces.ini at Dag parse time.",
+                "enum": SCRIPT_INTERFACES,
+                "values_display": {
+                    name: name.replace("Interface", "Interface ") for name in SCRIPT_INTERFACES
+                },
+                "section": "Typed parameters with Param object",
+            },
+        ),
         # [END section_1]
         # Boolean as proper parameter with description
         "bool": Param(