August 17, 2023

tJavaRow – Docs for ESB 5.x

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tJavaRow

tJavaRow_icon32.png

tJavaRow properties

Component Family

Custom Code

  

Function

tJavaRow allows you to enter
customized code which you can integrate in a Talend programme. With tJavaRow, you can enter the Java code to
be applied to each row of the flow.

Purpose

tJavaRow allows you to broaden
the functionality of Talend Jobs, using
the Java language.

Basic settings

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.

This component offers the advantage of the dynamic schema feature. This allows you to
retrieve unknown columns from source files or to copy batches of columns from a source
without mapping each column individually. For further information about dynamic schemas,
see Talend Studio
User Guide.

This dynamic schema feature is designed for the purpose of retrieving unknown columns
of a table and is recommended to be used for this purpose only; it is not recommended
for the use of creating tables.

 

 

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.

When the schema to be reused has default values that are integers or functions, ensure that
these default values are not enclosed within quotation marks. If they are, you must remove
the quotation marks manually.

For more details, see https://help.talend.com/display/KB/Verifying+default+values+in+a+retrieved+schema.
   

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.

 

Code

Enter the Java code to be applied to each line of the data
flow.

Advanced settings

Import

Enter the Java code required to import, if required, the external
library used in the Main code field
of the Basic settings tab.

 

tStatCatcher Statistics

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

Global Variables

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.

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.

To enter a global variable (for example COUNT of
tFileRowCount) in the Code box, you need to type in the entire piece of code manually, that is to
say ((Integer)globalMap.get(“tFileRowCount_COUNT”)).

Usage

This component is used as an intermediary between two other
components. It must be linked to both an input and an output
component.

Limitation

Knowledge of Java language is necessary.

Scenario 1: Transforming data
line by line using tJavaRow

In this scenario, the information of a few cities read from an input delimited file is
transformed using Java code through the tJavaRow
component and printed on the console.

use_case-tjavarow1-1.png

Setting up the Job

  1. Drop a tFileInputDelimited component and
    a tJavaRow component from the Palette onto the design workspace, and label them
    to better identify their roles in the Job.

  2. Connect the two components using a Row >
    Main connection.

Configuring the components

  1. Double-click the tFileInputDelimited
    component to display its Basic settings
    view in the Component tab.

    use_case-tjavarow1-2.png

  2. In the File name/Stream field, type in
    the path to the input file in double quotation marks, or browse to the path
    by clicking the […] button, and define
    the first line of the file as the header.

    In this example, the input file has the following content:

  3. Click the […] button next to Edit
    schema to open the [Schema] dialog box, and
    define the data structure of the input file. Then, click OK to validate the schema setting and close the
    dialog box.

    use_case-tjavarow1-3.png

  4. Double-click the tJavaRow component to
    display its Basic settings view in the
    Component tab.

    use_case-tjavarow1-4.png

  5. Click Sync columns to make sure that the
    schema is correctly retrieved from the preceding component.

  6. In the Code field, enter the code to be
    applied on each line of data based on the defined schema columns.

    In this example, we want to transform the city names to upper case, group
    digits of numbers larger than 1000 using the thousands separator for ease of
    reading, and print the data on the console:

    Note

    In the Code field, input_row refers to the link that connects to
    tJavaRow.

Saving and executing the Job

  1. Press Ctrl+S to save your Job.

  2. Press F6 or click Run on the Run tab to
    execute the Job.

    The city information is transformed by the Java code set through tJavaRow and displayed on the console.

    use_case-tjavarow1-5.png

Scenario 2: Using tJavaRow to handle file content based on a dynamic schema

This scenario describes a three-component Job that uses Java code through a tJavaRow component to display the content of an input file
and pass it to the output component. As all the components in this Job support the
dynamic schema feature, we can leverage this feature to save the time of configuring
each column of the schema.

Setting up the Job

  1. Drop tFileInputDelimited, tJavaRow, and tFileOutputDelimited from the Palette onto the design workspace, and label them according
    to their roles in the Job.

  2. Connect the components in a series using Row > Main links.

    use_case-tjavarow2-1.png

Configuring the input and output components

  1. Double-click the tFileInputDelimited
    component, which is labeled Source, to
    display its Basic settings view.

    use_case-tjavarow2-2.png

    Warning

    The dynamic schema feature is only supported in Built-In mode and requires the input file
    to have a header row.

  2. In the File name/Stream field, type in
    the path to the input file in double quotation marks, or browse to the path
    by clicking the […] button.

  3. In the Header field, type in 1 to define the first line of the file as the
    header.

  4. Click the […] button next to Edit schema to open the [Schema] dialog box.

    use_case-tjavarow2-3.png

  5. Click the [+] button to add a column,
    give a name to the column, dyna in this
    example, and select Dynamic from the
    Type list. This dynamic column will
    retrieve the three columns, FirstName,
    LastName and Address, of the input file.

  6. Click OK to validate the setting and
    close the dialog box.

  7. Double-click the tFileOutputDelimited
    component, which is labeled Target, to
    display its Basic settings view.

    use_case-tjavarow2-4.png

  8. Define the output file path in the File
    Name     field.

  9. Select the Include Header check box to
    include the header in the output file. Leave all the other settings are they
    are.

Configuring the tJavaRow component

  1. Double-click tJavaRow to display its
    Basic settings view and define the
    components properties.

    use_case-tjavarow2-5.png

  2. Click Sync columns to make sure that the
    schema is correctly retrieved from the preceding component.

  3. In the Code field, enter the following
    code to display the content of the input file and pass the data to the next
    component based on the defined dynamic schema column:

    Note

    In the Code field, input_row and output_row correspond to the links to and from tJavaRow.

Saving and executing the Job

  1. Press Ctrl+S to save your Job.

  2. Pressing F6, or click Run on the Run
    tab to execute the Job.

    The content of the input file is displayed on the console and written to
    the output file.

    use_case-tjavarow2-6.png
Document get from Talend https://help.talend.com
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