Projection¶

Module: aiodynamodb.projection Import: from aiodynamodb import ProjectionAttr

ProjectionAttr¶

A DynamoDB projection attribute path. Inherits from boto3 AttributeBase.

ProjectionAttr("user_id")
ProjectionAttr("address.city")
ProjectionAttr("basket.items[0].qty")

Pass a list of ProjectionAttr instances as projection_expression to: - db.get() - db.query() - db.transact_get() (via TransactGet) - db.batch_get() (via BatchGet)

Path syntax¶

Supports dot notation for nested maps and [n] for list indexing:

ProjectionExpressionArg¶

Type alias:

type ProjectionExpressionArg = list[ProjectionAttr]

This is the type accepted by all projection_expression parameters.

ProjectionExpressionBuilder¶

Internal class that compiles a list of ProjectionAttr into a DynamoDB ProjectionExpression string with ExpressionAttributeNames for reserved word escaping.

Used internally by the client — you do not call this directly.

BuiltProjectionExpression¶

@dataclass
class BuiltProjectionExpression:
    projection_expression: str
    expression_attribute_names: dict[str, str]

The compiled output of ProjectionExpressionBuilder. Contains the expression string and the placeholder-to-name mapping.