Insert models in the database with SQLAlchemy

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Inserting models with SQLAlchemy couldn't be easier! We'll use the db.session¹ variable to .add() a model. Let's begin working on our Item resource:

resources/item.py

@blp.arguments(ItemSchema)
@blp.response(201, ItemSchema)
def post(self, item_data):
    item = ItemModel(**item_data)

    try:
        db.session.add(item)
        db.session.commit()
    except SQLAlchemyError:
        abort(500, message="An error occurred while inserting the item.")

    return item

Similarly in our Store resource:

resources/store.py

@blp.arguments(StoreSchema)
    @blp.response(201, StoreSchema)
    def post(self, store_data):
        store = StoreModel(**store_data)
        try:
            db.session.add(store)
            db.session.commit()
        except IntegrityError:
            abort(
                400,
                message="A store with that name already exists.",
            )
        except SQLAlchemyError:
            abort(500, message="An error occurred creating the store.")

        return store

Note here we're catching two different errors, IntegrityError for when a client attempts to create a store with a name that already exists, and SQLAlchemyError for anything else.

Since the StoreModel's name column is marked as unique=True, then an IntegrityError is raised when we try to insert another row with the same name.

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1. Session Basics (SQLAlchemy Documentation)↩