Extent

This class represents a geographic aggregate used to compute the bounding box of a set of geometries. It initializes with a 2D extent specification and utilizes a specialized field type to handle the resulting spatial data. The class also provides a mechanism to convert database-specific extent values into a standardized format via the connection's operations.

Attributes

Attribute	Type	Description
name	string = "Extent"	The internal name of the aggregate function used for identification within the database backend.
is_extent	string = "2D"	A flag indicating the spatial dimensionality of the extent calculation, set to 2D for standard bounding boxes.

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Constructor

Signature

def Extent(
    expression: Any,
    **extra: dict
)

Parameters

Name	Type	Description
expression	Any	The SQL expression or field to aggregate.
**extra	dict	Additional keyword arguments for the aggregate function.

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Signature

def Extent(
    expression: [Expression](../../../../../db/models/expressions/expression.md?sid=django_db_models_expressions_expression),
    **extra: dict
)

Parameters

Name	Type	Description
expression	[Expression](../../../../../db/models/expressions/expression.md?sid=django_db_models_expressions_expression)	The field name or expression representing the geometries to be aggregated into a bounding box.
**extra	dict	Additional keyword arguments to be passed to the parent GeoAggregate constructor.

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Methods

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convert_value()

@classmethod
def convert_value(
    value: Any,
    expression: [Expression](../../../../../db/models/expressions/expression.md?sid=django_db_models_expressions_expression),
    connection: DatabaseConnection
) - > tuple

Converts the raw database value into a format suitable for the Extent field using the backend-specific operations.

Parameters

Name	Type	Description
value	Any	The raw value returned from the database driver.
expression	[Expression](../../../../../db/models/expressions/expression.md?sid=django_db_models_expressions_expression)	The expression that produced the value being converted.
connection	DatabaseConnection	The current database connection providing backend-specific conversion logic.

Returns

Type	Description
tuple	A four-item tuple representing the (xmin, ymin, xmax, ymax) coordinates of the extent.

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