Database-Level Validation

The create and update methods perform validation on the passed values at the database level. Specifically:

Foreign Keys Existence Validation

If Child.parent_id is a ForeignKey referencing Parent.id, and the value of parent_id is set via child_manager.create or child_manager.update, an SQL query will be executed to check the existence of a Parent with the provided ID.

If no such object exists, an fastapi.HTTPException will be raised.

Many-to-Many Relationships Existence Validation

If Post.tags represents a ManyToMany relationship with Tag.id, and the tags value is set via post_manager.create or post_manager.update as a list of IDs, an SQL query will be executed to verify the existence of all Tag objects with the provided IDs.

If any of the objects do not exist, an fastapi.HTTPException will be raised.

Unique Fields Validation

If Post.slug is a field defined with unique=True, and the value of slug is set via post_manager.create or post_manager.update, an SQL query will be executed to check that no other Post object exists with the same slug value.

If the uniqueness constraint is violated, an fastapi.HTTPException will be raised.

Unique Constraints Validation

If the model defines unique constraints using sqlalchemy.UniqueConstraint, then when using the create or update methods, an SQL query will be executed to verify that no other objects with the same combination of field values in the unique constraint exist.

If the unique constraint is violated, an fastapi.HTTPException will be raised.