[GitHub] [airflow] ashb commented on a diff in pull request #29946: Delay ConnectionModelView init until it's accessed

["ashb (via GitHub)" <gi...@apache.org>]

ashb commented on code in PR #29946:
URL: https://github.com/apache/airflow/pull/29946#discussion_r1127720560


##########
airflow/www/views.py:
##########
@@ -4397,7 +4376,42 @@ class ConnectionModelView(AirflowModelView):
 
     base_order = ("conn_id", "asc")
 
-    extra_field_name_mapping: dict[str, str] = {}
+    def _iter_extra_field_names(self) -> Iterator[tuple[str, str]]:
+        """Iterate through provider-backed connection fields.
+
+        Note that this cannot be a property (including a cached property)
+        because Flask-Appbuilder attempts to access all members on startup, and
+        using a property would initialize the providers manager too eagerly.
+        """
+        return ((k, v.field_name) for k, v in ProvidersManager().connection_form_widgets.items())
+
+    @property
+    def add_columns(self) -> list[str]:
+        """A list of columns to show in the Add form.
+
+        This dynamically calculates additional fields from providers and add
+        them to the backing list. This calculation is done exactly once (by
+        checking we're referencing the class-level variable instead of the
+        instance-level), and only after we enter the request context (to skip
+        superfuluous checks done by Flask-Appbuilder on startup).
+        """
+        if self._add_columns is type(self)._add_columns and has_request_context():
+            self._add_columns = [*self._add_columns, *(k for k, _ in self._iter_extra_field_names())]
+        return self._add_columns
+
+    @property
+    def edit_columns(self) -> list[str]:
+        """A list of columns to show in the Edit form.
+
+        This dynamically calculates additional fields from providers and add
+        them to the backing list. This calculation is done exactly once (by
+        checking we're referencing the class-level variable instead of the
+        instance-level), and only after we enter the request context (to skip
+        superfuluous checks done by Flask-Appbuilder on startup).
+        """
+        if self._edit_columns is type(self)._edit_columns and has_request_context():
+            self._edit_columns = [*self._edit_columns, *(k for k, _ in self._iter_extra_field_names())]
+        return self._edit_columns

Review Comment:
   Do add and edit columns differ? Could this be simply be `return self.add_columns`?



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