Package org.apache.datafusion

Class ScalarUdf

java.lang.Object

org.apache.datafusion.ScalarUdf

public final class ScalarUdf
extends Object

A scalar UDF registration handle: pairs a ScalarFunction implementation with the metadata DataFusion needs to dispatch SQL calls to it.

Mirrors DataFusion's ScalarUDF struct. Construct one from a ScalarFunction via fromImpl(ScalarFunction) (or the public constructor) and pass it to SessionContext.registerUdf(ScalarUdf).

Constructor Summary

Constructors

Constructor	Description
ScalarUdf(ScalarFunction impl)	Wrap a ScalarFunction for registration.

Method Summary

Modifier and Type	Method	Description
List<org.apache.arrow.vector.types.pojo.Field>	argFields()	Declared argument fields; cached from ScalarFunction.argFields().
static ScalarUdf	fromImpl(ScalarFunction impl)	Equivalent to new ScalarUdf(impl); mirrors Rust's ScalarUDF::new_from_impl.
ScalarFunction	impl()	The wrapped implementation.
String	name()	SQL name; cached from ScalarFunction.name().
org.apache.arrow.vector.types.pojo.Field	returnField()	Declared return field; cached from ScalarFunction.returnField().
Volatility	volatility()	Volatility classification; cached from ScalarFunction.volatility().

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ScalarUdf

public ScalarUdf(ScalarFunction impl)

Wrap a ScalarFunction for registration. Each metadata getter is invoked once here and cached, so a user impl that allocates per call won't be double-evaluated at registration.

Throws:

NullPointerException - if impl or any of its declared metadata is null

Method Details

fromImpl

public static ScalarUdf fromImpl(ScalarFunction impl)

Equivalent to new ScalarUdf(impl); mirrors Rust's ScalarUDF::new_from_impl.

impl

public ScalarFunction impl()

The wrapped implementation.

name

public String name()

SQL name; cached from ScalarFunction.name().

argFields

public List<org.apache.arrow.vector.types.pojo.Field> argFields()

Declared argument fields; cached from ScalarFunction.argFields().

returnField

public org.apache.arrow.vector.types.pojo.Field returnField()

Declared return field; cached from ScalarFunction.returnField().

volatility

public Volatility volatility()

Volatility classification; cached from ScalarFunction.volatility().