tWriteJSONField - 6.1

Talend Components Reference Guide

EnrichVersion
6.1
EnrichProdName
Talend Big Data
Talend Big Data Platform
Talend Data Fabric
Talend Data Integration
Talend Data Management Platform
Talend Data Services Platform
Talend ESB
Talend MDM Platform
Talend Open Studio for Big Data
Talend Open Studio for Data Integration
Talend Open Studio for Data Quality
Talend Open Studio for ESB
Talend Open Studio for MDM
Talend Real-Time Big Data Platform
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Function

tWriteJSONField transforms the incoming data into JSON fields.

Purpose

tWriteJSONField transforms the incoming data into JSON fields and transfers them to a file, a database table, etc.

If you have subscribed to one of the Talend solutions with Big Data, this component is available in the following types of Jobs:

Configuring a JSON Tree

When configuring a JSON tree, the default type of an element is string. If an element is not of type string, you need to add an attribute for the element to set its type.

  • For an integer, double, float, or boolean element, you need to add an attribute named type and set its static value to integer, number, float, or boolean respectively.

  • For an array element, you need to add an attribute named class and set its static value to array, and then add a sub-element named element set as a loop.

  • For an object element, you need to add an attribute named class and set its static value to object.

The following figure shows an example of JSON tree configuration:

tWriteJSONField properties

Component family

Processing/Fields

 

Basic settings

Output Column

List of the columns defined in the output schema to hold the JSON field generated.

 

Configure JSON Tree

Opens the interface to create the JSON data structure. For more information, see Configuring a JSON Tree.

 

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.

 

Sync columns

Click to synchronize the output file schema with the input file schema. The Sync function only displays once the Row connection is linked with the output component.

 

Group by

Define the aggregation set, the columns you want to use to regroup the data.

Warning

Make sure that the data to be grouped is in sequential order.

 

Remove root node

Select this check box to remove the root node from the JSON field generated.

Advanced settings

 

tStatCatcher Statistics

Select this check box to gather the Job processing metadata at a 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

Preceded by an input component, this component wraps the incoming data into a JSON field.

Scenario: Writing flat data into JSON fields

In this scenario, flat data is wrapped into JSON fields via tWriteJSONField.

Linking the components

  1. Drop the following components from the Palette onto the design workspace: tFixedFlowInput, tWriteJSONField and tLogRow.

  2. Link tFixedFlowInput and tWriteJSONField using a Row > Main connection.

  3. Link tWriteJSONField and tLogRow using a Row > Main connection.

Configuring the components

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

  2. Click Edit schema to open the schema editor.

    Click the [+] button to add three columns, namely firstname, lastname and dept, with the type of string.

    Click OK to close the editor.

  3. Select the Use Inline Content option and enter the data below in the Content box:

    Andrew;Wallace;Doc
    John;Smith;R&D
    Christian;Dior;Sales
  4. Click tWriteJSONField to display its Basic settings view.

    Select the Remove root node option to remove the root node setting from the JSON fields generated.

  5. Click Configure JSON Tree to open the XML tree editor.

    The schema of tFixedFlowInput appears in the Linker source panel.

  6. In the Linker target panel, click the default rootTag and type in staff, which is the root node of the JSON field to be generated.

  7. Right-click staff and select Add Sub-element from the context menu.

  8. In the pop-up box, enter the sub-node name, namely firstname.

    Repeat the steps to add two more sub-nodes, namely lastname and dept.

  9. Right-click firstname and select Set As Loop Element from the context menu.

  10. Drop firstname from the Linker source panel to its counterpart in the Linker target panel.

    In the pop-up dialog box, select Add linker to target node.

    Click OK to close the dialog box.

    Repeat the steps to link the two other items.

    Click OK to close the XML tree editor.

  11. Click Edit schema to open the schema editor.

  12. Click the [+] button in the right panel to add one column, namely staff, which will hold the JSON data generated.

    Click OK to close the editor.

  13. Double-click tLogRow to display its Basic settings view.

    Select Table (print values in cells of a table) for a better display of the results.

Executing the Job

  1. Press Ctrl + S to save the Job.

  2. Click F6 to execute the Job.

    As shown above, the JSON fields have been generated correctly, with the root node settings removed.

tWriteJSONField in Talend Map/Reduce Jobs

Warning

The information in this section is only for users that have subscribed to one of the Talend solutions with Big Data and is not applicable to Talend Open Studio for Big Data users.

In a Talend Map/Reduce Job, tWriteJSONField, as well as the other Map/Reduce components preceding it, generates native Map/Reduce code. This section presents the specific properties of tWriteJSONField when it is used in that situation. For further information about a Talend Map/Reduce Job, see Talend Big Data Getting Started Guide.

Component family

Processing/Fields

 

Basic settings

Output Column

List of the columns defined in the output schema to hold the JSON field generated.

 

Configure JSON Tree

Opens the interface to create the JSON data structure. For more information, see Configuring a JSON Tree.

 

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.

 

Sync columns

Click to synchronize the output file schema with the input file schema. The Sync function only displays once the Row connection is linked with the output component.

 

Group by

Define the aggregation set, the columns you want to use to regroup the data.

Warning

Make sure that the data to be grouped is in sequential order.

 

Remove root node

Select this check box to remove the root node from the JSON field generated.

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 in Map/Reduce Jobs

In a Talend Map/Reduce Job, this component is used as an intermediate step and other components used along with it must be Map/Reduce components, too. They generate native Map/Reduce code that can be executed directly in Hadoop.

You need to use the Hadoop Configuration tab in the Run view to define the connection to a given Hadoop distribution for the whole Job.

For further information about a Talend Map/Reduce Job, see the sections describing how to create, convert and configure a Talend Map/Reduce Job of the Talend Big Data Getting Started Guide.

Note that in this documentation, unless otherwise explicitly stated, a scenario presents only Standard Jobs, that is to say traditional Talend data integration Jobs, and non Map/Reduce Jobs.

Related scenarios

No scenario is available for the Map/Reduce version of this component yet.

tWriteJSONField properties in Spark Batch Jobs

Component family

Processing/Fields

 

 Basic settings

Editor

Opens the interface to create the JSON data structure. For more information, see Configuring a JSON Tree.

 

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.

 

Sync columns

Click to synchronize the output file schema with the input file schema. The Sync function only displays once the Row connection is linked with the output component.

 

Group by

Define the aggregation set, the columns you want to use to regroup the data.

Warning

Make sure that the data to be grouped is in sequential order.

 

Remove root node

Select this check box to remove the root node from the JSON field generated.

Usage in Spark Batch Jobs

In a Talend Spark Batch Job, this component is used as an intermediate step and other components used along with it must be Spark Batch components, too. They generate native Spark Batch code that can be executed directly in a Spark cluster.

This component, along with the Spark Batch component Palette it belongs to, appears only when you are creating a Spark Batch Job.

Note that in this documentation, unless otherwise explicitly stated, a scenario presents only Standard Jobs, that is to say traditional Talend data integration Jobs.

Spark Connection

You need to use the Spark Configuration tab in the Run view to define the connection to a given Spark cluster for the whole Job. In addition, since the Job expects its dependent jar files for execution, one and only one file system related component from the Storage family is required in the same Job so that Spark can use this component to connect to the file system to which the jar files dependent on the Job are transferred:

This connection is effective on a per-Job basis.

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.

Related scenarios

No scenario is available for the Spark Batch version of this component yet.

tWriteJSONField properties in Spark Streaming Jobs

Warning

The streaming version of this component is available in the Palette of the studio on the condition that you have subscribed to Talend Real-time Big Data Platform or Talend Data Fabric.

Component family

Processing/Fields

 

Basic settings

Output type

Select the type of the data to be outputted into the target file. The data is byte arrays if you select byte[].

 

Editor

Opens the interface to create the JSON data structure. For more information, see Configuring a JSON Tree.

 

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.

 

Sync columns

Click to synchronize the output file schema with the input file schema. The Sync function only displays once the Row connection is linked with the output component.

 

Group by

Define the aggregation set, the columns you want to use to regroup the data.

Warning

Make sure that the data to be grouped is in sequential order.

 

Remove root node

Select this check box to remove the root node from the JSON field generated.

Usage in Spark Streaming Jobs

In a Talend Spark Streaming Job, this component is used as an intermediate step and other components used along with it must be Spark Streaming components, too. They generate native Spark Streaming code that can be executed directly in a Spark cluster.

This component, along with the Spark Streaming component Palette it belongs to, appears only when you are creating a Spark Streaming Job.

Note that in this documentation, unless otherwise explicitly stated, a scenario presents only Standard Jobs, that is to say traditional Talend data integration Jobs.

Spark Connection

You need to use the Spark Configuration tab in the Run view to define the connection to a given Spark cluster for the whole Job. In addition, since the Job expects its dependent jar files for execution, one and only one file system related component from the Storage family is required in the same Job so that Spark can use this component to connect to the file system to which the jar files dependent on the Job are transferred:

This connection is effective on a per-Job basis.

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.

Related scenarios

No scenario is available for the Spark Streaming version of this component yet.