July 30, 2023

tSampleRow – Docs for ESB 7.x

tSampleRow

Selects rows according to a list of single lines and/or a list of groups of
lines.

tSampleRow filters rows
according to line numbers.

tSampleRow Standard properties

These properties are used to configure tSampleRow running in the Standard Job framework.

The Standard
tSampleRow component belongs to the Processing family.

The component in this framework is available in all Talend
products
.

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.

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 in the Job.

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 the schema and store it
locally for the relevant component. 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
.

Range

Enter a range using the relevant syntax to choose a list of single lines and/or
a list of groups of lines.

Global Variables

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

Usage rule

This component handles flows of data therefore it requires input and output
components.

Filtering rows and groups of rows

This scenario describes a three-component Job. A tRowGenerator is used to create random entries which are directly sent to a
tSampleRow where they will be filtered according to a
defined range. In this scenario, we suppose the input flow contains names of salespersons
along with their respective number of sold products and their years of presence in the
enterprise. The result of the filtering operation is displayed on the Run console.

Dropping and linking the components

  1. Drop the following components from the Palette onto
    the design workspace: tRowGenerator, tSampleRow, and tLogRow.
  2. Connect the three components using Row > Main links.

tSampleRow_1.png

Configuring the components

  1. In the design workspace, select tRowgenerator, and
    click the Component tab to define the basic settings
    for tRowGenerator.
  2. Click the […] button next to Edit Schema to define the data you want to use as input. In
    this scenario, the schema is made of five columns.

    tSampleRow_2.png

  3. In the Basic settings view, click RowGenerator Editor to define the data to be generated.
  4. In the RowGenerator Editor, specify the number of
    rows to be generated in the Number of Rows for
    RowGenerator
    field and click OK. The
    RowGenerator Editor closes.

    tSampleRow_3.png

  5. In the design workspace, select tSampleRow and
    click the Component tab to define the basic settings
    for tSampleRow.

    tSampleRow_4.png

  6. In the Basic settings view, set the Schema to Built-In and click
    Sync columns to retrieve the schema from the
    tRowGenerator component.
  7. In the Range panel, set the filter to select your
    rows using the correct syntax as explained. In this scenario, we want to select the
    first and fifth lines along with the group of lines between 9 and 12.
  8. In the design workspace, select tLogRow and click
    the Component tab to define its basic settings. For
    more information about tLogRow, see tLogRow.

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.
tSampleRow_5.png

The filtering result displayed on the console shows the first and fifth rows and the
group of rows between 9 and 12.


Document get from Talend https://help.talend.com
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