python - Simple Inventory App in Django, count residual -


i building small inventory tracking app , wondering how organize database , logic. fresh in django. came basic db scheme: db schema inventory app django (link image)

so wondering if going use arrangement how derive list of residual inventory, ready exported json, probably, , represent in django view properly?

*one of ideas create model list of balances on each inventory item , updated each time new item received or existing used. approach worked extent seems prone mistakes or double entries. *


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