tForeach - 6.3

Talend Open Studio for Big Data Components Reference Guide

EnrichVersion
6.3
EnrichProdName
Talend Open Studio for Big Data
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Function

tForeach creates a loop on a list for an iterate link.

Purpose

tForeach allows you to to create a loop on a list for an iterate link.

tForeach Properties

Component Family

Orchestration

 

Basic settings

Values

Use the [+] button to add rows to the Values table. Then click on the fields to enter the list values to be iterated upon, between double quotation marks.

Advanced settings

tStatCatcher Statistics

Select this check box to collect the log data at a component level.

Global Variables

ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box.

CURRENT_VALUE: the value currently iterated upon. This is a Flow variable and it returns a string.

A Flow variable functions during the execution of a component while an After variable functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl + Space to access the variable list and choose the variable to use from it.

For further information about variables, see Talend Studio User Guide.

Usage

tForeach is an input component and requires an Iterate link to connect it to another component.

Log4j

If you are using a subscription-based version of the Studio, the activity of this component can be logged using the log4j feature. For more information on this feature, see Talend Studio User Guide.

For more information on the log4j logging levels, see the Apache documentation at http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html.

Limitation

n/a

Scenario: Iterating on a list and retrieving the values

This scenario describes a two component Job in which a list is created and iterated upon in a tForeach component. The values are then retrieved in a tJava component.

  • Drop a tForeach and a tJava component onto the design workspace:

  • Link tForeach to tJava using a Row > Iterate connection.

  • Double-click tForeach to open its Basic settings view:

  • Click the [+] button to add as many rows to the Values list as required.

  • Click on the Value fields to enter the list values, between double quotation marks.

  • Double-click tJava to open its Basic settings view:

  • Enter the following Java code in the Code area: System.out.println(globalMap.get("tForeach_1_CURRENT_VALUE")+"_out");

  • Save the Job and press F6 to run it

    The tJava run view displays the list values retrieved from tForeach, each one suffixed with _out: