Fetching related parent objects in a chain in Django

Question

As always, please forgive my ignorance. I promise I searched first.

Ive got my Django views put together for my employee class. One of the properties is the report_to field. This field is populated by a FK to another user obj.

My task now is to build a command tree. So I need a list of A reports to B reports to C reports to D all the way up the chain.

At first I thought is this would end up being a looped queury, but there has to be a better solution.

Prefetch_related maybe? Or select_related?

How do I get this to grab all the relations until it reaches ceo and reports_to is null?

Daniel Roseman · Accepted Answer · 2013-11-18 15:27:19Z

2

What you have there is a tree structure, with the CEO at the top. Those aren't easy to represent in databases generally. Luckily there is a nice algorithm that will do it for you, MPTT, and a great Django implementation in django-mptt. It will involve some changes to your data, but using that will allow you to get all ancestors of an employee - or all descendants - in one go.

answered Nov 18, 2013 at 15:27

Daniel Roseman

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meteorainer Over a year ago

Been doing some research on MPTT. Looks right up my ally. Good call. Thanks

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