[GitHub] [airflow] OmairK commented on a change in pull request #9597: [WIP] Add read-only endpoints for task instances

[GitBox <gi...@apache.org>]

OmairK commented on a change in pull request #9597:
URL: https://github.com/apache/airflow/pull/9597#discussion_r478796025



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File path: airflow/api_connexion/schemas/task_instance_schema.py
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@@ -0,0 +1,147 @@
+# 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 typing import List, NamedTuple
+
+from marshmallow import Schema, fields, ValidationError, post_load
+from marshmallow_sqlalchemy import SQLAlchemySchema, auto_field
+from sqlalchemy import and_
+
+from airflow.api_connexion.schemas.enum_schemas import TaskInstanceStateField
+from airflow.api_connexion.schemas.sla_miss_schema import SlaMissSchema
+from airflow.models import DagRun, TaskInstance, SlaMiss
+from airflow.utils.session import create_session
+
+
+class TaskInstanceSchema(Schema):
+    """Task instance schema"""
+
+    task_id = fields.Str()
+    dag_id = fields.Str()
+    execution_date = fields.DateTime()
+    start_date = fields.DateTime()
+    end_date = fields.DateTime()
+    duration = fields.Float()
+    state = TaskInstanceStateField()
+    _try_number = fields.Int(data_key="try_number")
+    max_tries = fields.Int()
+    hostname = fields.Str()
+    unixname = fields.Str()
+    pool = fields.Str()
+    pool_slots = fields.Int()
+    queue = fields.Str()
+    priority_weight = fields.Int()
+    operator = fields.Str()
+    queued_dttm = fields.DateTime(data_key="queued_when")
+    pid = fields.Int()
+    executor_config = fields.Str()
+    sla_miss = fields.Method("get_sla_miss")
+
+    @staticmethod
+    def get_sla_miss(obj: TaskInstance):
+        with create_session() as session:
+            sla_miss = session.query(SlaMiss).filter(

Review comment:
       Hey @mik-laj we are not using relationships in the model so I was planning to use explicit joins to overcome this n + 1 problem the only downside of that it is returns a tuple of object `(<task instance>,<sla miss>)` so I was planning to overwrite [`get_attribute`](https://marshmallow.readthedocs.io/en/stable/api_reference.html#marshmallow.Schema.get_attribute). Let me know if this sounds like a good idea. I will be doing something similar here 
   ```
   class TaskInstanceReferenceSchema(Schema):
       """Schema for the task instance reference schema"""
       task_id = fields.Str()
       dag_run_id = fields.Method('get_run_id')
       dag_id = fields.Str()
       execution_date = fields.DateTime()
   
       @staticmethod
       def get_run_id(obj: TaskInstance):
           with create_session() as session:
               return session.query(DagRun).filter(DagRun.dag_id==obj.dag_id, DagRun.execution_date==obj.execution_date).one_or_none().run_id
   ```




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