Map

Short Description

Map manipulates record’s structure or content. This component was formerly called Reformat.

COMPONENT	SAME INPUT METADATA	SORTED INPUTS	INPUTS	OUTPUTS	JAVA	CTL	AUTO-PROPAGATED METADATA
Map	-	x	1	1-N	✓	✓	✓

Ports

PORT TYPE	NUMBER	REQUIRED	DESCRIPTION	METADATA
Input	0	✓	For input data records	Any(In0)
Output	0	✓	For transformed data records	Any(Out0)
	1-n	x	For transformed data records	Any(OutPortNo)

This component has one input port and at least one output port.

The component can send different records to different output ports or even send the same data record to more output ports.

Metadata

Map propagates metadata from the input port to the output port (from left to right), but it does not propagate metadata from the output port to the input port (from right to left). Metadata propagation through Map has low priority.

Map Attributes

ATTRIBUTE	REQ	DESCRIPTION	POSSIBLE VALUES
BASIC
Transform	[1]	The definition of how records should be mapped. Written in the graph source either in CTL or in Java.
Transform URL	[1]	The name of the external file, including the path, containing the definition of the way how records should be mapped; written in CTL or Java.
Transform class	[1]	The name of an external class defining the way how records should be mapped.
Transform source charset		Encoding of external file defining the transformation. The default encoding depends on DEFAULT_SOURCE_CODE_CHARSET in defaultProperties.	E.g. UTF-8
DEPRECATED
Error actions		The definition of an action that should be performed when the specified transformation returns an Error code. See Return Values of Transformations.
Error log		The URL of the file to which error messages for specified Error actions should be written. If not set, they are written to Console.

[1] One of these must be specified. Any of these transformation attributes uses a CTL template for Map or implements a RecordTransform interface.

For more information, see CTL Scripting Specifics or Java Interfaces for Map below.

For detailed information about transformations, see also Defining Transformations.

Details

Map receives potentially unsorted data through the single input port, transforms each of them in a user-specified way and sends the resulting record to the port(s) specified by the user. Return values of the transformation are numbers of output port(s) to which data record will be sent.

A transformation must be defined. The transformation uses a CTL template for Map, implements a RecordTransform interface or inherits from a DataRecordTransform superclass. The interface methods are listed below.

CTL Scripting Specifics

When you define any of the three transformation attributes, specify a transformation that assigns a number of output port to each input record.

For detailed information about Data Shaper Transformation Language, see CTL2 - Data Shaper Transformation Language. (CTL is a full-fledged, yet simple language that allows you to perform almost any imaginable transformation.)

CTL scripting allows you to specify a custom transformation using the simple CTL scripting language.

CTL Templates for Map

Map uses the same transformation template as DataIntersection and Joiners. For more information, see CTL Templates for Joiners.

Java Interfaces for Map

Map implements the same interface as DataIntersection and Joiners. For more information, see Java Interfaces for Joiners.

Examples

Using Map to drop field(s)

This example shows a way to use Map to drop unnecessary metadata fields.

Input metadata contains the firstname, surname and address fields. Output metadata contains the firstname and surname fields. Drop the address field.

Solution In Map, specify the Transform attribute:

function integer transform() {
    $out.0.firstname = $in.0.firstname;
    $out.0.surname = $in.0.surname;

    return ALL;
}

You can use $out.0.* = $in.0.*; instead of specifying the mapping of particular fields.

Splitting the records

This example shows a way to use Map to split one record to multiple parts and send each part to a different output port.

Input metadata contains the ID, firstname, surname and address fields. Send ID, firstname and surname to the first output port and ID and address to the second output port.

Solution In Map, set the Transform attribute.

function integer transform() {
    $out.0.ID = $in.0.ID;
    $out.0.firstname = $in.0.firstname;
	$out.0.surname = $in.0.surname;

    $out.1.ID = $in.0.ID;
    $out.1.address = $in.0.address;

    return ALL;
}

Filtering records

Map can be used as a filter.

Input metadata contains the ID and color fields. Valid colors are red, green, or blue. Send red items to the first output port; green items to the second output port; and blue items to the third output port. Items without correct color should be send to the fourth output port.

Solution

function integer transform() {
    if ( $in.0.color == "red" ) {
        $out.0.* = $in.0.*;
        return 0;
    }
    if ( $in.0.color == "green" ) {
        $out.1.* = $in.0.*;
        return 1;
    }
    if ( $in.0.color == "blue") {
        $out.2.* = $in.0.*;
        return 2;
    }

    $out.3.* = $in.0.*;
    return 3;
}

The component specialized on filtering of records is Filter.

Best Practices

Use Map To

• Drop unwanted fields

• Validate fields using functions or Regular Expressions
• Calculate new or modify existing fields

• Convert data types

If the transformation is specified in an external file (with Transform URL), we recommend users to explicitly specify Transform source charset.

See also

Common Properties of Components Specific attribute types Common Properties of Transformers