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Python

James J. McCombie
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James J. McCombie
Python Web Development Techdegree Graduate 21,199 Points
Posted by James J. McCombie
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James J. McCombie
Python Web Development Techdegree Graduate 21,199 Points

Database ORM foreign key's

I have put this question in python's category, because I am mainly dealing with databases via Pewee and Django.

A ForeignKeyField stores in a row in a table, a reference to the primary key of a row in another table I believe.

So what happens if the row in the table is deleted, the ForeignKeyField contains a reference to a row that no longer exists?

James

1 Answer

Tatiana Vasilevskaya
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Tatiana Vasilevskaya
Python Web Development Techdegree Graduate 28,600 Points
Tatiana Vasilevskaya
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Tatiana Vasilevskaya
Python Web Development Techdegree Graduate 28,600 Points

I suggest you check ForeignKey.on_delete argument documentation. https://docs.djangoproject.com/en/1.10/ref/models/fields/#arguments There are various options you can choose when an object referenced by Foreign Key is deleted (delete object containing the foreign key, set the value to NULL, set the value to default, etc).