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pythondjangodjango-models
zheaton
zheaton

Reputation: 13

Django design patterns - models with ForeignKey references to multiple classes

I'm working through the design of a Django inventory tracking application, and have hit a snag in the model layout. I have a list of inventoried objects (Assets), which can either exist in a Warehouse or in a Shipment. I want to store different lists of attributes for the two types of locations, e.g.:

Since each Warehouse and Shipment can contain multiple Assets, but each Asset can only be in one place at a time, adding a ForeignKey relationship to the Asset model seems like the way to go. However, since Warehouse and Shipment objects have different data models, I'm not certain how to best do this.

One obvious (and somewhat ugly) solution is to create a Location model which includes all of the Shipment and Warehouse attributes and an is_warehouse Boolean attribute, but this strikes me as a bit of a kludge. Are there any cleaner approaches to solving this sort of problem (Or are there any non-Django Python libraries which might be better suited to the problem?)

Upvotes: 0

Views: 241

Answers (2)

jdi
jdi

Reputation: 92559

I think its perfectly reasonable to create a "through" table such as location, which associates an asset, a content (foreign key) and a content_type (warehouse or shipment) . And you could set a unique constraint on the asset_fk so thatt it can only exist in one location at a time

Upvotes: 0

Dave LeBlanc
Dave LeBlanc

Reputation: 251

what about having a generic foreign key on Assets?

Upvotes: 1

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