danieldekay/ai-ops/django-model-to-domain-converter

When to Use

Use this skill when working with Django models in a Clean Architecture project and need to convert infrastructure layer models to domain entities. Applies when adding to_domain methods to map ORM models to framework-free domain objects.

Procedure

1. Identify the domain entity structure

• Read the domain entity file (e.g., src/tangoatlas/domain/auth/user.py)
• Understand the dataclass structure and required fields
• Note any value objects or complex types used

1. Locate the Django model

• Find the corresponding infrastructure layer model (e.g., src/tangoatlas/infrastructure/django/auth/models.py)
• Identify the model class that needs the to_domain method

1. Implement the to_domain method

```python def to_domain(self) -> DomainEntity: """Convert Django model to domain entity.

Returns: DomainEntity: Framework-free domain object """ return DomainEntity( id=self.id, # Map fields from model to domain entity field_name=self.field_name, # Handle optional fields optional_field=self.optional_field if self.optional_field else None, # Convert value objects coordinates=Coordinates( latitude=self.point.y, longitude=self.point.x ) ) ```

1. Handle field mapping

• Direct field mapping: field=self.field
• Optional fields: field=self.field if self.field else None
• Value objects: Create instances with proper typing
• PostGIS coordinates: Extract from PointField using .x and .y
• Foreign keys: Convert to domain references or IDs

1. Add typing and documentation

• Import the domain entity type
• Add return type annotation
• Include docstring explaining the conversion
• Handle TYPE_CHECKING imports properly

1. Test the conversion

• Verify all required fields are mapped
• Check optional field handling
• Test with edge cases (null values, empty strings)
• Ensure no framework dependencies leak into domain

Pitfalls

• Circular imports: Use TYPE_CHECKING guard to prevent import cycles
• Missing fields: Ensure all domain entity fields are mapped from model
• Null handling: Properly handle optional/nullable fields in domain
• Framework leakage: Never import Django classes in domain layer
• PostGIS coordinates: Remember PointField uses (x, y) not (lat, lon)

Verification

• Run type checking with basedpyright
• Verify no import errors in domain layer
• Test conversion with sample data
• Check that domain entities remain framework-free