io.cdap.directives.transformation

Class ColumnExpression

java.lang.Object

io.cdap.directives.transformation.ColumnExpression

All Implemented Interfaces:

Directive, Executor<List<Row>,List<Row>>, Lineage, Serializable

@Categories(categories="transform")
public class ColumnExpression
extends Object
implements Directive, Lineage

A directive for apply an expression to store the result in a column. The expressions are specified in JEXL format (http://commons.apache.org/proper/commons-jexl/reference/syntax.html) Executor is response for executing only one expression for each Row record that is being passed. The result of expression either adds a new column or replaces the value of the existing column.

Executor step = new ColumnExpression(lineno, directive, column, "if (age > 24 ) { 'adult' } else { 'teen' }");

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	NAME

Fields inherited from interface io.cdap.wrangler.api.Directive

TYPE

Constructor Summary

Constructors

Constructor and Description
ColumnExpression()

Method Summary

Modifier and Type	Method and Description
UsageDefinition	define()
void	destroy()
List<Row>	execute(List<Row> rows, ExecutorContext context)
void	initialize(Arguments args)
Mutation	lineage()

Methods inherited from class java.lang.Object

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

Field Detail

NAME

public static final String NAME

See Also:

Constant Field Values

Constructor Detail

ColumnExpression

public ColumnExpression()

Method Detail

define

public UsageDefinition define()

Specified by:

define in interface Directive

initialize

public void initialize(Arguments args)
                throws DirectiveParseException

Specified by:

initialize in interface Executor<List<Row>,List<Row>>

Throws:

DirectiveParseException

destroy

public void destroy()

Specified by:

destroy in interface Executor<List<Row>,List<Row>>

execute

public List<Row> execute(List<Row> rows,
                         ExecutorContext context)
                  throws DirectiveExecutionException

Specified by:

execute in interface Executor<List<Row>,List<Row>>

Throws:

DirectiveExecutionException

lineage

public Mutation lineage()

Specified by:

lineage in interface Lineage