I have an email sending tasks running in celery shared task. i am passing a python list into html template. but celery converts this list into string. but without using celery task , i am getting actual list.
From the docs you can read:
Data transferred between clients and workers needs to be serialized, so every message in Celery has a content_type header that describes the serialization method used to encode it.
The default serializer is JSON, but you can change this using the task_serializer setting, or for each individual task, or even per message.
As serializers, you can use also pickle, yaml and msgpack but the data, MUST be serialized.
Serialization is mandatory, just keep in mind tasks will be communicating using JSON (that's your case) and de-serialize the data before using it.