标签:SQLAlchemy parent Constraint some App db foreign key id
db.relationship
- Allows SQLAlchemy to identify relationships between models
- Links relationships with backrefs (child1.some_parent)
- Configures relationship dynamics between parents and children
- db.relationship does not set up foreign key constraints for you. We need to add a column, some_parent_id, on the child model that has a foreign key constraint
- Whereas we set db.relationship on the parent mode, we set the foreign key constraint on the child model.
- A foreign key constraint prefers referential integrity from one table to another, by ensuring that the foreign key column always maps a primary key in the foreign table.
CREATE TABLE vehicles (
id INTEGER PRIMARY KEY,
make VARCHAR NOT NULL,
model VARCHAR NOT NULL,
year INTEGER NOT NULL,
driver_id REFERENCES drivers(id)
)
driver_id maps to an id that belongs in the drivers table.
driver_id is nonempty
db.ForeignKey
- Option in db.column to specify a foreign key constraint, referring to the primary key of the other table / model
- Gets defined on the Child model
class SomeParent(db.Model):
__tablename__ = 'some_parents'
id = db.Column(db.Integer, primary_key=True)
...
class SomeChild(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(50), nullable=False)
#some_parents.id: Maps to parent table's primary key
# format: {parent tablename}.{parent primary key column name}
some_parent_id = db.Column(db.Integer, db.ForeignKey('some_parents.id'), nullable=False)
标签:SQLAlchemy,parent,Constraint,some,App,db,foreign,key,id 来源: https://blog.csdn.net/BSCHN123/article/details/121561470
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