org.apache.flink.table.sources

Interface FieldComputer<T>

Type Parameters:

T - The result type of the provided expression.

All Known Implementing Classes:

ExistingField, StreamRecordTimestamp, TimestampExtractor

@PublicEvolving
public interface FieldComputer<T>

The FieldComputer interface returns an expression to compute the field of the table schema of a TableSource from one or more fields of the TableSource's return type.

Method Summary

Modifier and Type	Method and Description
String[]	getArgumentFields() Returns the names of all fields that the expression of the field computer accesses.
Expression	getExpression(ResolvedFieldReference[] fieldAccesses) Returns the Expression that computes the value of the field.
TypeInformation<T>	getReturnType() Returns the result type of the expression.
void	validateArgumentFields(TypeInformation<?>[] argumentFieldTypes) Validates that the fields that the expression references have the correct types.

Method Detail

getArgumentFields

String[] getArgumentFields()

Returns the names of all fields that the expression of the field computer accesses.

Returns:

An array with the names of all accessed fields.

getReturnType

TypeInformation<T> getReturnType()

Returns the result type of the expression.

Returns:

The result type of the expression.

validateArgumentFields

void validateArgumentFields(TypeInformation<?>[] argumentFieldTypes)

Validates that the fields that the expression references have the correct types.

Parameters:

argumentFieldTypes - The types of the physical input fields.

getExpression

Expression getExpression(ResolvedFieldReference[] fieldAccesses)

Returns the Expression that computes the value of the field.

Parameters:

fieldAccesses - Field access expressions for the argument fields.

Returns:

The expression to extract the timestamp from the TableSource return type.