I'm starting to create my first web application in Django. I'm dealing with backEnd part first. In my data structure I need to calculate some fields like average budget of employee's salary for each model object (company, department ..).

I found some ways to calculate and display calculated field in API.

1. Add a property into model and override querySet for better performance.
2. Calculate and add extra field in serializers and display it for API.
3. Use build-in computedfields.models

I can not decide which way is best for calculating fields, what are pros and cons of each way.

Thanks for some advice.