Add more fields to REST API get DAG(dags/dag_id) endpoint

The DagModel columns have increased since this endpoint was created. This PR improves the
endpoint by including all the missing fields of the DagModel on the endpoint.

This update also touched on DAGDetails schema because it inherits from DAGSchema.
In a future PR, when more details would be added to the DAGDetails endpoint, we could
separate it from the DAGSchema. They are related but not really the same. One is a
database object while the other is not

airflow/api_connexion/openapi/v1.yaml

@@ -2111,6 +2111,58 @@ components:
           description: Whether the DAG is SubDAG.
           type: boolean
           readOnly: true
+        last_parsed_time:
+          type: string
+          format: date-time
+          readOnly: true
+          nullable: true
+          description: |
+            The last time the DAG was parsed.
+
+            *New in version 2.3.0*
+        last_pickled:
+          type: string
+          format: date-time
+          readOnly: true
+          nullable: true
+          description: |
+            The last time the DAG was pickled.
+
+            *New in version 2.3.0*
+        last_expired:
+          type: string
+          format: date-time
+          readOnly: true
+          nullable: true
+          description: |
+            Time when the DAG last received a refresh signal
+            (e.g. the DAG's "refresh" button was clicked in the web UI)
+
+            *New in version 2.3.0*
+        scheduler_lock:
+          type: boolean
+          readOnly: true
+          nullable: true
+          description: |
+            Whether (one of) the scheduler is scheduling this DAG at the moment
+
+            *New in version 2.3.0*
+        pickle_id:
+          type: string
+          readOnly: true
+          nullable: true
+          description: |
+            Foreign key to the latest pickle_id
+
+            *New in version 2.3.0*
+        default_view:
+          type: string
+          nullable: true
+          readOnly: true
+          description: |
+            Default view of the DAG inside the webserver
+
+            *New in version 2.3.0*
         fileloc:
           description: The absolute path to the file.
           type: string
@@ -2136,13 +2188,89 @@ components:
             describe DAG contents.
         schedule_interval:
           $ref: '#/components/schemas/ScheduleInterval'
+        timetable_description:
+          type: string
+          readOnly: true
+          nullable: true
+          description: |
+            Timetable/Schedule Interval description.
+
+            *New in version 2.3.0*
         tags:
           description: List of tags.
           type: array
           nullable: true
           items:
             $ref: '#/components/schemas/Tag'
           readOnly: true
+        max_active_tasks:
+          type: integer
+          nullable: true
+          readOnly: true
+          description: |
+            Maximum number of active tasks that can be run on the DAG
+
+            *New in version 2.3.0*
+        max_active_runs:
+          type: integer
+          nullable: true
+          readOnly: true
+          description: |
+            Maximum number of active DAG runs for the DAG
+
+            *New in version 2.3.0*
+        has_task_concurrency_limits:
+          type: boolean
+          nullable: true
+          readOnly: true
+          description: |
+            Whether the DAG has task concurrency limits
+
+            *New in version 2.3.0*
+        has_import_errors:
+          type: boolean
+          nullable: true
+          readOnly: true
+          description: |
+            Whether the DAG has import errors
+
+            *New in version 2.3.0*
+        next_dagrun:
+          type: string
+          format: date-time
+          readOnly: true
+          nullable: true
+          description: |
+            The logical date of the next dag run.
+
+            *New in version 2.3.0*
+        next_dagrun_data_interval_start:
+          type: string
+          format: date-time
+          readOnly: true
+          nullable: true
+          description: |
+            The start of the interval of the next dag run.
+
+            *New in version 2.3.0*
+        next_dagrun_data_interval_end:
+          type: string
+          format: date-time
+          readOnly: true
+          nullable: true
+          description: |
+            The end of the interval of the next dag run.
+
+            *New in version 2.3.0*
+        next_dagrun_create_after:
+          type: string
+          format: date-time
+          readOnly: true
+          nullable: true
+          description: |
+            Earliest time at which this ``next_dagrun`` can be created.
+
+            *New in version 2.3.0*
 
     DAGCollection:
       description: |

airflow/api_connexion/schemas/dag_schema.py

@@ -51,12 +51,27 @@ class Meta:
     is_paused = auto_field()
     is_active = auto_field(dump_only=True)
     is_subdag = auto_field(dump_only=True)
+    last_parsed_time = auto_field(dump_only=True)
+    last_pickled = auto_field(dump_only=True)
+    last_expired = auto_field(dump_only=True)
+    scheduler_lock = auto_field(dump_only=True)
+    pickle_id = auto_field(dump_only=True)
+    default_view = auto_field(dump_only=True)
     fileloc = auto_field(dump_only=True)
     file_token = fields.Method("get_token", dump_only=True)
     owners = fields.Method("get_owners", dump_only=True)
     description = auto_field(dump_only=True)
     schedule_interval = fields.Nested(ScheduleIntervalSchema)
+    timetable_description = auto_field(dump_only=True)
     tags = fields.List(fields.Nested(DagTagSchema), dump_only=True)
+    max_active_tasks = auto_field(dump_only=True)
+    max_active_runs = auto_field(dump_only=True)
+    has_task_concurrency_limits = auto_field(dump_only=True)
+    has_import_errors = auto_field(dump_only=True)
+    next_dagrun = auto_field(dump_only=True)
+    next_dagrun_data_interval_start = auto_field(dump_only=True)
+    next_dagrun_data_interval_end = auto_field(dump_only=True)
+    next_dagrun_create_after = auto_field(dump_only=True)
 
     @staticmethod
     def get_owners(obj: DagModel):

airflow/models/dag.py

@@ -2689,7 +2689,7 @@ class DagModel(Base):
     owners = Column(String(2000))
     # Description of the dag
     description = Column(Text)
-    # Default view of the inside the webserver
+    # Default view of the DAG inside the webserver
     default_view = Column(String(25))
     # Schedule interval
     schedule_interval = Column(Interval)