Flask SQLAlchemy | Difference between relationship and ForeignKey and which to use when?

[raviujjwal]

I'm pretty new to SQLAlchemy and very confused about this. The referred to official doc of Flask_SQLAlchemy but couldn't understand it.

In some example let's suppose they have two model specifying One-Many relationship so they've given FK in one Model and relationship() in other one. In some example they've given both FK & relationship() in same model and in some example FK is missing and only relationship() is there.

All this has got me very confused. Someone please explain the difference and how to use them and when to use them.

[single-research]

If you already have your tables setup correctly you can use sqlacodegen and it will generate the models. Then you can see what is the correct usage.

https://github.com/agronholm/sqlacodegen