tRowGenerator - 6.3

Talend Open Studio for Big Data Components Reference Guide

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tRowGenerator generates as many rows and fields as are required using random values taken from a list.


It can be used to create an input flow in a Job for testing purposes, in particular for boundary test sets

The tRowGenerator Editor opens up on a separate window made of two parts: a Schema definition panel at the top of the window and a Function definition and preview panel at the bottom.

Defining the schema

First you need to define the structure of data to be generated.

  • Add as many columns to your schema as needed, using the plus (+) button.

  • Type in the names of the columns to be created in the Columns area and select the Key check box if required

  • Make sure you define then the nature of the data contained in the column, by selecting the Type in the list. According to the type you select, the list of Functions offered will differ. This information is therefore compulsory.

  • Some extra information, although not required, might be useful such as Length, Precision or Comment. You can also hide these columns, by clicking on the Columns drop-down button next to the toolbar, and unchecking the relevant entries on the list.

  • In the Function area, you can select the predefined routine/function if one of them corresponds to your needs.You can also add to this list any routine you stored in the Routine area of the Repository. Or you can type in the function you want to use in the Function definition panel. Related topic: see Talend Studio User Guide.

  • Click Refresh to have a preview of the data generated.

  • Type in a number of rows to be generated. The more rows to be generated, the longer it'll take to carry out the generation operation.

Defining the function

Select the [...] under Function in the Schema definition panel in order to customize the function parameters.

  • Select the Function parameters tab

  • The Parameter area displays Customized parameter as function name (read-only)

  • In the Value area, type in the Java function to be used to generate the data specified.

  • Click on the Preview tab and click Preview to check out a sample of the data generated.

tRowGenerator properties

Component family



Basic settings

Schema and Edit schema

A schema is a row description. It defines the number of fields (columns) to be processed and passed on to the next component. The schema is either Built-In or stored remotely in the Repository.

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: You create and store the schema locally for this component only. Related topic: see Talend Studio User Guide.



Repository: You have already created the schema and stored it in the Repository. You can reuse it in various projects and Job designs. Related topic: see Talend Studio User Guide.


RowGenerator editor

The editor allows you to define the columns and the nature of data to be generated. You can use predefined routines or type in the function to be used to generate the data specified.

Note that in a Storm Job, the value -1 in the Number of rows for RowGenerator field in the RowGenerator editor means to generate infinite rows of input data.

Advanced settings

tStatCatcher Statistics

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

Global Variables

NB_LINE: the number of rows processed. This is an After variable and it returns an integer.

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.


The tRowGenerator Editor's ease of use allows users without any Java knowledge to generate random data for test purposes.


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



Scenario: Generating random java data

The following scenario creates a two-component Job, generating 50 rows structured as follows: a randomly picked-up ID in a 1-to-3 range, a random ascii First Name and Last Name generation and a random date taken in a defined range.

  • Drop a tRowGenerator and a tLogRow component from the Palette to the design workspace.

  • Right-click tRowGenerator and select Row > Main. Drag this main row link onto the tLogRow component and release when the plug symbol displays.

  • Double click tRowGenerator to open the Editor.

  • Define the fields to be generated.

  • The random ID column is of integer type, the First and Last names are of string type and the Date is of date type.

  • In the Function list, select the relevant function or set on the three dots for custom function.

  • On the Function parameters tab, define the Values to be randomly picked up.

  • First_Name and Last_Name columns are to be generated using the getAsciiRandomString function that is predefined in the system routines. By default the length defined is 6 characters long. You can change this if need be.

  • The Date column calls the predefined getRandomDate function. You can edit the parameter values in the Function parameters tab.

  • Set the Number of Rows to be generated to 50.

  • Click OK to validate the setting.

  • Double click tLogRow to view the Basic settings. The default setting is retained for this Job.

  • Press F6 to run the Job.

The 50 rows are generated following the setting defined in the tRowGenerator editor and the output is displayed in the Run console.