# tExtractJSONFields MapReduce properties (deprecated) Availability-note[Deprecated](https://help.talend.com/r/en-US/Cloud/labels-on-talend-help-center/availability-deprecated) This content is deprecated. These properties are used to configure tExtractJSONFields running in the MapReduce Job framework. The MapReduce tExtractJSONFields component belongs to the Processing family. The component in this framework is available in all Talend products with Big Data and Talend Data Fabric. Availability-note[Deprecated](https://help.talend.com/r/en-US/Cloud/labels-on-talend-help-center/availability-deprecated) This content is deprecated. The MapReduce framework is deprecated from Talend 7.3 onwards. Use Talend Jobs for Apache Spark to accomplish your integration tasks. ## Basic settings | Property type | Either Built-In or Repository. | | --- | --- | | | Built-In: No property data stored centrally. | | | Repository: Select the repository file where the
properties are stored. | | 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. When you create a Spark
Job, avoid the reserved word line when naming the
fields.

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. | | | Repository: You have already created the schema and stored it in the
Repository. You can reuse it in various projects and Job designs. | | Read by | Select a way of extracting the JSON data in the file.

Xpath: Extracts the JSON data based on the XPath query.
JsonPath: Extracts the JSON data based on the JSONPath query. Note that it is recommended to read the data by JSONPath in order to gain better performance.

| | JSON field | List of the JSON fields to be extracted. | | Loop Jasonpath query | Enter the Jsonpath or XPath of the node on which the loop is based.

Note if you have selected Xpath from the Read by drop-down list, the Loop
Xpath query field is displayed instead. | | Mapping | Complete this table to map the columns defined in the schema to the
corresponding JSON nodes.

Column: The Column cells are automatically filled with the defined schema column names.
Json query/JSONPath query: Specify the JSONPath node that holds the desired data. For more information about JSONPath expressions, see http://goessner.net/articles/JsonPath/.

This column is available only when JsonPath is selected from the Read By list.
XPath query: Specify the XPath node that holds the desired data.

This column is available only when Xpath is selected from the Read By list.
Get Nodes: Select this check box to extract the JSON data of all the nodes or select the check box next to a specific node to extract the data of that node.

This column is available only when Xpath is selected from the Read By list.
Is Array: select this check box when the JSON field to be extracted is an array instead of an object.

This column is available only when Xpath is selected from the Read By list.

| | Die on error | Select the check box to stop the execution of the Job when an error
occurs.

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. | ## Advanced settings | Encoding | Select the encoding from the list or select Custom
and define it manually. This field is compulsory for database data handling. The
supported encodings depend on the JVM that you are using. For more information, see
[https://docs.oracle.com](https://docs.oracle.com/). | | --- | --- | ## 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.

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 | **Usage rule** | 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. | | --- | --- |