tIterateToFlow - 6.1

Talend Components Reference Guide

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6.1
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Talend Big Data
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task
Data Governance
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Design and Development
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Talend Studio

tIterateToFlow Properties

Component family

Orchestration

 

Function

tIterateToFlow transforms a list into a data flow that can be processed.

Purpose

Allows you to transform non processable data into a processable flow.

Basic settings

Schema and Edit Schema

A schema is a row description, it defines the number of fields that will be processed and passed on to the next component. The schema is either Built-in or remote in the Repository.

Since version 5.6, both the Built-In mode and the Repository mode are available in any of the Talend solutions.

Click Edit schema to make changes to the schema. If the current schema is of the Repository type, three options are available:

  • View schema: choose this option to view the schema only.

  • Change to built-in property: choose this option to change the schema to Built-in for local changes.

  • Update repository connection: choose this option to change the schema stored in the repository and decide whether to propagate the changes to all the Jobs upon completion. If you just want to propagate the changes to the current Job, you can select No upon completion and choose this schema metadata again in the [Repository Content] window.

 

 

Built-in: The schema will be created and stored locally for this component only. Related topic: see Talend Studio User Guide.

 

 

Repository: The schema already exists and is stored in the Repository, hence can be reused in various projects and Job designs. Related topic: see Talend Studio User Guide.

 

Mapping

Column: Enter a name for the column to be created

Value: Press Ctrl+Space to access all of the available variables, be they global or user-defined.

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.

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

This component is not startable (green background) and it requires an output component.

Connections

Outgoing links (from this component to another):

Row: Main.

Trigger: Run if; On Component Ok; On Component Error.

Incoming links (from one component to this one):

Row: Iterate;

For further information regarding connections, see Talend Studio User Guide.

Scenario: Transforming a list of files as data flow

The following scenario describes a Job that iterates on a list of files, picks up the filename and current date and transforms this into a flow, that gets displayed on the console.

  • Drop the following components: tFileList, tIterateToFlow and tLogRow from the Palette to the design workspace.

  • Connect the tFileList to the tIterateToFlow using an iterate link and connect the Job to the tLogRow using a Row main connection.

  • In the tFileList Component view, set the directory where the list of files is stored.

  • In this example, the files are three simple .txt files held in one directory: Countries.

  • No need to care about the case, hence clear the Case sensitive check box.

  • Leave the Include Subdirectories check box unchecked.

  • Then select the tIterateToFlow component et click Edit Schema to set the new schema

  • Add two new columns: Filename of String type and Date of date type. Make sure you define the correct pattern in Java.

  • Click OK to validate.

  • Notice that the newly created schema shows on the Mapping table.

  • In each cell of the Value field, press Ctrl+Space bar to access the list of global and user-specific variables.

  • For the Filename column, use the global variable: tFileList_1CURRENT_FILEPATH. It retrieves the current filepath in order to catch the name of each file, the Job iterates on.

  • For the Date column, use the Talend routine:TalendDate.getCurrentDate() (in Java)

  • Then on the tLogRow component view, select the Print values in cells of a table check box.

  • Save your Job and press F6 to execute it.

The filepath displays on the Filename column and the current date displays on the Date column.