tFileInputARFF - 6.1

Talend Components Reference Guide

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Design and Development

tFileInputARFF properties

Component Family




tFileInputARFF reads a ARFF file row by row, with simple separated fields.


This component opens a file and reads it row by row, in order to divide it in fields and to send these fields to the next component, as defined in the schema, through a Row connection.

Basic settings

Property type

Either Built-in or Repository.

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



Built-in: No property data stored centrally.



Repository: Select the repository file where the properties are stored. The fields that follow are completed automatically using the data retrieved.


Click this icon to open a connection wizard and store the Excel file connection parameters you set in the component's Basic settings view.

For more information about setting up and storing file connection parameters, see Talend Studio User Guide.


File Name

Name and path of the ARFF file and/or variable to be processed.

For further information about how to define and use a variable in a Job, see Talend Studio User Guide.


Schema and Edit Schema

A schema is a row description, it defines the number of fields to be processed and passed on to the next component. The schema is either Built-in or stored remotely 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 flowcharts. Related topic: see Talend Studio User Guide.

Advanced settings


Select the encoding type from the list or select Custom and define it manually. This field is compulsory for DB data handling.


tStatCatcher Statistics

Select this check box to gather the processing metadata at the Job level as well as at each 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.


Use this component to read a file and separate the fields with the specified separator.


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


Due to license incompatibility, one or more JARs required to use this component are not provided. You can install the missing JARs for this particular component by clicking the Install button on the Component tab view. You can also find out and add all missing JARs easily on the Modules tab in the Integration perspective of your studio. For details, see or the section describing how to configure the Studio in the Talend Installation Guide.

Scenario: Display the content of a ARFF file

This scenario describes a two-component Job in which the rows of an ARFF file are read, the delimited data is selected and the output is displayed in the Run view.

An ARFF file looks like the following:

It is generally made of two parts. The first part describes the data structure, that is to say the rows which begin by @attribute and the second part comprises the raw data, which follows the expression @data.

Dropping and linking components

  1. Drop the tFileInputARFF component from the Palette onto the workspace.

  2. In the same way, drop the tLogRow component.

  3. Right-click the tFileInputARFF and select Row > Main in the menu. Then, drag the link to the tLogRow, and click it. The link is created and appears.

Configuring the components

  1. Double-click the tFileInputARFF.

  2. In the Component view, in the File Name field, browse your directory in order to select your .arff file.

  3. In the Schema field, select Built-In.

  4. Click the [...] button next to Edit schema to add column descriptions corresponding to the file to be read.

  5. Click on the button as many times as required to create the number of columns required, according to the source file. Name the columns as follows.

  6. For every column, the Nullable check box is selected by default. Leave the check boxes selected, for all of the columns.

  7. Click OK.

  8. In the workspace, double-click the tLogRow to display its Component view.

  9. Click the [...] button next to Edit schema to check that the schema has been propagated. If not, click the Sync columns button.

Saving and executing the Job

  1. Press Ctrl+S to save your Job.

  2. Press F6 to execute your Job.

    The console displays the data contained in the ARFF file, delimited using a vertical line (the default separator).