Airflow 2.2.2 - templating conn not defined - jinja2

Question

I'm using Airflow 2.2.2 with the latest providers installed as appropriate.
I'm trying to use the Azure and MySQL hooks and have created custom operators with templates defined for what variables can be templated.
When I do so, I get an error saying that conn or var cannot be found
e.g. my passed parameter is
{{ conn.<variable_name> }}
or
{{ var.json.value.<variable_name> }}
I believe this should be possible in > v2.0 but not working for me, any ideas why?
EDIT: Below are snippets of code with some sensitive information removed, let me know if anything else is needed?
DAG error -
Broken DAG: [/home/dags/dag.py] Traceback (most recent call last):
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/home/dags/dag.py", line 52, in <module>
wasb_conn_id = {{ conn.wasb }},
NameError: name 'conn' is not defined
task in dag.py
t1 = WasbLogBlobsToCSVOperator(
task_id='task_xyz',
wasb_conn_id = {{ conn.wasb }},
Custom Operator using an extended version of the Microsoft Azure wasb hook , used by dag.py -
class WasbLogBlobsToCSVOperator(BaseOperator):
template_fields = (
'wasb_conn_id',
)
def __init__(
self,
*,
wasb_conn_id: str = 'wasb',
**kwargs,
) -> None:
super().__init__(**kwargs)
self.wasb_conn_id = wasb_conn_id
self.hook = ExtendedWasbHook(wasb_conn_id=self.wasb_conn_id)

Answer 1

There looks to be a few things going on here that should help.
Jinja templates are string expressions. Try wrapping your wasb_conn_id arg in quotes.
wasb_conn_id = "{{ conn.wasb }}",
Templated fields are not rendered until the task runs meaning the Jinja expression won't be evaluated until an operator's execute() method is called. This is why you are seeing an exception from your comment below. The literal string "{{ conn.wasb }}" is being evaluated as the conn_id. If you want to use a template field in the custom operator, you need to move that logic to be in the scope of the execute() method.
Why do you need to use a Jinja expression here? Since the format of accessing the Connection object via Jinja is {{ conn.<my_conn_id> }}, you could just use the value "wasb" directly.