tExtractDelimitedFields - 6.1

Talend Open Studio for Big Data Components Reference Guide

EnrichVersion
6.1
EnrichProdName
Talend Open Studio for Big Data
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Function

tExtractDelimitedFields generates multiple columns from a delimited string column.

Purpose

tExtractDelimitedFields helps to extract 'fields' from within a string to write them elsewhere for example.

tExtractDelimitedFields properties

Component family

Processing/Fields

 

Basic settings

Field to split

Select an incoming field from the Field to split list to split.

 

Ignore NULL as the source data

Select this check box to ignore the Null value in the source data.

Clear this check box to generate the Null records that correspond to the Null value in the source data.

 

Field separator

Enter character, string or regular expression to separate fields for the transferred data.

Note

Since this component uses regex to split a filed and the regex syntax uses special characters as operators, make sure to precede the regex operator you use as a field separator by a double backslash. For example, you have to use "\\|" instead of "|".

 

Die on error

Clear the check box to skip any rows on error and complete the process for error-free rows. When errors are skipped, you can collect the rows on error using a Row > Reject link.

 

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.

Click Sync columns to retrieve the schema from the previous component connected in the Job.

 

 

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.

Advanced settings

Advanced separator (for number)

Select this check box to change the separator used for numbers. By default, the thousands separator is a comma (,) and the decimal separator is a period (.).

 

Trim column

Select this check box to remove leading and trailing whitespace from all columns.

 

Check each row structure against schema

Select this check box to check whether the total number of columns in each row is consistent with the schema. If not consistent, an error message will be displayed on the console.

 

Validate date

Select this check box to check the date format strictly against the input schema.

 

tStatCatcher Statistics

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

NB_LINE: the number of rows read by an input component or transferred to an output component. This is an After variable and it returns an integer.

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 handles flow of data therefore it requires input and output components. It allows you to extract data from a delimited field, using a Row > Main link, and enables you to create a reject flow filtering data which type does not match the defined type.

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: Extracting a delimited string column of a database table

This scenario describes a Job that writes data including a delimited string column into a MySQL database table and displays the data on the console, then extracts the delimited string column into multiple columns and displays the data after extraction on the console.

Adding and linking components

  1. Create a new Job and add the following components by typing their names in the design workspace or dropping them from the Palette: a tFixedFlowInput component, a tMysqlOutput component, a tMysqlInput component, a tExtractDelimitedFields component, two tLogRow components.

  2. Link tFixedFlowInput to tMysqlOutput using a Row > Main connection.

  3. Do the same to link tMysqlOutput to the first tLogRow, link tMysqlInput to tExtractDelimitedFields, link tExtractDelimitedFields to the second tLogRow.

  4. Link tFixedFlowInput to tMysqlInput using a Trigger > On Subjob Ok connection.

Configuring the components

Populating data in a MySQL database table

  1. Double-click tFixedFlowInput to open its Basic settings view.

  2. Click the [...] button next to Edit schema and in the pop-up window define the schema by adding three columns: Id of Integer type, and Name and DelimitedField of String type.

    Click OK to close the schema editor and accept the propagation prompted by the pop-up dialog box.

  3. In the Mode area, select Use Inline Content(delimited file). Then in the Content field displayed, enter the data to write to the database. This input data includes a delimited string column. In this example, the input data is as follows:

    1;AAA;32,Component Team,Developer
    2;BBB;28,Component Team,Tester
    3;CCC;30,Doc Team,Writer
    4;DDD;35,Doc Team,Leader
    5;EEE;33,QA Team,Tester
  4. Double-click tMysqlOutput to open its Basic settings view.

  5. Fill the Host, Port, Database, Username, Password fields with the MySQL database connection information.

  6. Fill the Table field with the name of the table to be written. In this example, it is employee.

  7. Select Drop table if exists and create from the Action on table list.

  8. Double-click the first tLogRow to open its Basic settings view.

    In the Mode area, select Table (print values in cells of a table) for better readability of the result.

Extracting the delimited string column in the database table into multiple columns

  1. Double-click tMysqlInput to open its Basic settings view.

  2. Fill the Host, Port, Database, Username, Password fields with the MySQL database connection information.

  3. Click the [...] button next to Edit schema and in the pop-up window define the schema of the tMysqlInput component same as the schema of the tMysqlOutput component.

  4. In the Table Name field, enter the name of the table into which the data was written. In this example, it is employee.

  5. Click the Guess Query button to fill the Query field with the SQL query statement to be executed on the specified table. In this example, it is as follows:

    SELECT 
      `employee`.`Id`, 
      `employee`.`Name`, 
      `employee`.`DelimitedField`
    FROM `employee`
  6. Double-click tExtractDelimitedFields to open its Basic settings view.

  7. In the Field to split list, select the delimited string column to be extracted. In this example, it is DelimitedField.

    In the Field separator, enter the separator used to separate the fields in the delimited string column. In this example, it is ,.

  8. Click the [...] button next to Edit schema and in the pop-up window define the schema by adding five columns: Id of Integer type, and Name, Age, Team, Title of String type.

    In this example, the delimited string column DelimitedField is split into three columns Age, Team and Title, and the Id and Name columns are kept as well.

    Click OK to close the schema editor and accept the propagation prompted by the pop-up dialog box.

  9. Double-click the second tLogRow to open its Basic settings view.

    In the Mode area, select Table (print values in cells of a table) for better readability of the result.

Saving and executing the Job

  1. Press Ctrl + S to save the Job.

  2. Execute the Job by pressing F6 or clicking Run on the Run tab.

    As shown above, the primitive input data and the data after extraction are displayed on the console, and the delimited string column DelimitedField is extracted into three columns Age, Team, and Title.