# 'Manager' object has no attribute 'filter_by'

- **ID:** `python/django-attribute-error-manager`
- **Domain:** python
- **Category:** type_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Calling a custom method on a manager that doesn't exist, or using incorrect syntax.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.x | active | — | — |

## Workarounds

1. **Define custom manager method** (95% success)
   ```
   class MyModelManager(models.Manager):
    def filter_by(self, **kwargs):
        return self.filter(**kwargs)
class MyModel(models.Model):
    objects = MyModelManager()
   ```
2. **Use standard filter instead** (90% success)
   ```
   MyModel.objects.filter(field=value)
   ```

## Dead Ends

- **Assuming default manager has custom methods** — Default manager only provides standard QuerySet methods. (90% fail)
- **Using objects.filter_by without defining it** — Method must be defined in custom manager. (80% fail)