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# Custom Types
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Pydantic-compatible custom field types for MongoDB-specific data types like Decimal128 and Binary.
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## Capabilities
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### DecimalAnnotation
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```python { .api }
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DecimalAnnotation: TypeAlias
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"""Pydantic annotation for handling BSON Decimal128 types."""
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```
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### BsonBinary
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```python { .api }
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BsonBinary: TypeAlias
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"""Pydantic-compatible BSON binary field type."""
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```
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## Usage Examples
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```python
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from beanie import Document, DecimalAnnotation, BsonBinary
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from decimal import Decimal
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class Product(Document):
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    name: str
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    price: DecimalAnnotation  # High-precision decimal
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    image_data: BsonBinary    # Binary data
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    class Settings:
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        collection = "products"
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# Create with custom types
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product = Product(
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    name="Laptop",
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    price=Decimal("1299.99"),
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    image_data=b"binary_image_data"
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)
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await product.insert()
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```