SQLAlchemy Compatibility Mode¶

Saffier already supports SQLAlchemy-style expressions via Model.columns.<name>.

For progressive migrations from legacy SQLAlchemy models, you can opt in to class-attribute compatibility so Model.<name> resolves to SQLAlchemy columns.

Enable Per Model¶

import saffier
import sqlalchemy


class Workspace(saffier.SQLAlchemyModelMixin, saffier.StrictModel):
    id = saffier.IntegerField(primary_key=True, autoincrement=True)
    name = saffier.CharField(max_length=255)

    class Meta:
        registry = models


statement = sqlalchemy.select(Workspace.id).where(Workspace.id == 1)

Enable Once On An Abstract Base¶

If many models need this mode, declare it once on an abstract base model:

class SACompatBase(saffier.SQLAlchemyModelMixin, saffier.StrictModel):
    class Meta:
        abstract = True


class Workspace(SACompatBase):
    id = saffier.IntegerField(primary_key=True, autoincrement=True)
    name = saffier.CharField(max_length=255)

    class Meta:
        registry = models

Concrete subclasses inherit the compatibility behavior automatically.

What Works¶

On opted-in concrete models:

sqlalchemy.select(Workspace.id)
sqlalchemy.select(Workspace.id).where(Workspace.id == some_value)
sqlalchemy.select(Workspace.id).order_by(Workspace.id)

Foreign keys are exposed as scalar aliases using SQLAlchemy-style names:

# for `owner = saffier.ForeignKey(User, ...)`
Workspace.owner_id

What Does Not Work¶

Relationship collections and reverse relations are not scalar columns:

• Many-to-many fields such as Workspace.tags
• Reverse relationship fields
• RefForeignKey helper fields

For these, continue using Saffier's relationship and queryset APIs.

Compatibility Notes¶

• This mode is explicit and opt-in only.
• Non-opted-in models keep existing behavior, so Model.id still raises AttributeError.
• Existing Saffier query patterns keep working, including Model.columns.<name>, keyword filters, and Q.

FAQ¶

Can I enable this once in an abstract base model?¶

Yes. All concrete subclasses inherit the compatibility mode. You do not need to repeat SQLAlchemyModelMixin on every child model.

Does this change normal Saffier query behavior?¶

No. It only adds SQLAlchemy Core style class-attribute access for opted-in concrete models.