JSONExtract

Port type	Number	Required	Description	Metadata
Input	0	⨯	For port reading. See Reading from Input Port.	One field (`byte`, `cbyte`, `string`).
Output	0	✓	For correct data records	Any
1-n	^[1]	For correct data records	Any

Input

⨯

For port reading. See Reading from Input Port.

One field (byte, cbyte, string).

Output

✓

For correct data records

Any

1-n

^[1]

For correct data records

Any

¹	Other output ports are required if mapping requires that.

Metadata

JSONExtract does not propagate metadata.

JSONExtract has no metadata template.

Metadata on optional input port must contain string or byte or cbyte field.

Metadata on each output port does not need to be the same.

Each metadata can use Autofilling Functions.

JSONExtract Attributes

Attribute Req Description Possible values

Attribute	Req	Description	Possible values
Basic
File URL	yes	Attribute specifying what data source(s) will be read (JSON file, input port, dictionary). See Supported File URL Formats for Readers.
Charset		Encoding of records which are read.	any encoding, default system one by default
Mapping	^[1]	Mapping of the input JSON structure to output ports. For more information, see XMLExtract Mapping Definition.
Mapping URL	^[1]	Name of an external file, including its path which defines mapping of the input JSON structure to output ports. For more information, see XMLExtract Mapping Definition.
Equivalent XML Schema		URL of a file that should be used for creating the Mapping definition. For more information, see JSONExtract Mapping Editor and XSD Schema.
Use nested nodes		By default, nested elements are also mapped to output ports automatically. If set to `false`, an explicit `<Mapping>` tag must be created for each such nested element.	true (default) \| false
Trim strings		By default, white spaces from the beginning and the end of the elements values are removed. If set to `false`, they are not removed.	true (default) \| false
Advanced
Number of skipped mappings		Number of mappings to be skipped continuously throughout all source files. See Selecting Input Records.	0-N
Max number of rows to output		Maximum number of records to be read continuously throughout all source files. See Selecting Input Records.	0-N

Basic

File URL

yes

Attribute specifying what data source(s) will be read (JSON file, input port, dictionary). See Supported File URL Formats for Readers.

Charset

Encoding of records which are read.

any encoding, default system one by default

Mapping

^[1]

Mapping of the input JSON structure to output ports. For more information, see XMLExtract Mapping Definition.

Mapping URL

^[1]

Name of an external file, including its path which defines mapping of the input JSON structure to output ports. For more information, see XMLExtract Mapping Definition.

Equivalent XML Schema

URL of a file that should be used for creating the Mapping definition. For more information, see JSONExtract Mapping Editor and XSD Schema.

Use nested nodes

By default, nested elements are also mapped to output ports automatically. If set to false, an explicit <Mapping> tag must be created for each such nested element.

true (default) | false

Trim strings

By default, white spaces from the beginning and the end of the elements values are removed. If set to false, they are not removed.

true (default) | false

Advanced

Number of skipped mappings

Number of mappings to be skipped continuously throughout all source files. See Selecting Input Records.

0-N

Max number of rows to output

Maximum number of records to be read continuously throughout all source files. See Selecting Input Records.

0-N

¹	One of these must be specified. If both are specified, Mapping URL has higher priority.

Details

JSONExtract reads data from JSON files using SAX technology. This component is faster than JSONReader which can read JSON files too. JSONExtract does not use DOM, so it uses less memory than JSONReader.

JSONExtract can read lists.

JSONExtract can convert JSON to variant. Result variant can contain field/array values of following data types - null, string, boolean, long and number.

JSONExtract is very similar to XMLExtract. JSONExtract internally transforms JSON to XML and uses XMLExtract to parsing the data. Therefore, you can generate xsd file for corresponding xml file.

Mapping in JSONExtract is almost same as in XMLExtract. The main difference is, that JSON does not have attributes. For more information, see XMLExtract’s Details.

JSONExtract Mapping Editor and XSD Schema

JSONExtract Mapping Editor serves to set up mapping from JSON tree structure to one ore more output ports without the necessity of being aware how to create mapping of field using an XML editor.

To be able to use the editor, the editor needs to have created equivalent xsd schema. The equivalent xsd schema is created automatically. Only the directory for the schema needs to be specified.

Any other operations to set up mapping are described in above mentioned XMLExtract.

Mapping Input Fields to the Output Fields

In JSONExtract, you can map input fields to the output in the same way as you map JSON fields. The input field mapping works in all three processing modes.

Examples

Reading lists

JSON file contains information about employees and orders. Each item contains employee ID and list of order IDs.

{
  "jsonextract_order" : {
    "employee" : "Henri",
    "orders" : [ "order01", "order08", "order15" ]
  },
  "jsonextract_order" : {
    "employee" : "Jane",
    "orders" : [ "order02", "order05", "order09" ]
  }
}

Read data for further processing.

Solution

Use the File URL attribute to point to the source file and the Mapping attribute to define mapping.

Figure 336. JSONExtract - mapping the list

Reading variants

JSON file contains information about employees and orders. Each item contains employee ID and list of order IDs.

{
  "jsonextract_order" : {
    "employee" : "Henri",
    "orders" : [ "order01", "order08", "order15" ]
  },
  "jsonextract_order" : {
    "employee" : "Jane",
    "orders" : [ "order02", "order05", "order09" ]
  }
}

Read data for further processing.

Solution

Use the File URL attribute to point to the source file and the Mapping attribute to define mapping.

Figure 337. JSONExtract - mapping the variant

Content of mapped output variant field depends on structure of input JSON.

// for the first input element
$out.0.employeeData["jsonextract_order"]["employee"]; // contains 'Henri'
$out.0.employeeData["jsonextract_order"]["orders"][0]; // contains 'order01'

Best Practices

We recommend users to explicitly specify Charset.

Compatibility

Version	Compatibility Notice
3.5.0-M2	JSONExtract is available since 3.5.0-M2.
4.1.0-M1	You can now map input fields to the output fields in this component.
4.1.0	You can now read lists.
5.11.0	You can now extract JSON to variant.
5.11.0	Null values are no longer converted to an empty string on output.

Version

Compatibility Notice

3.5.0-M2

JSONExtract is available since 3.5.0-M2.

4.1.0-M1

You can now map input fields to the output fields in this component.

4.1.0

You can now read lists.

5.11.0

You can now extract JSON to variant.

5.11.0

Null values are no longer converted to an empty string on output.

JSONExtract

Short Description

Ports

Metadata

JSONExtract Attributes

Details

JSONExtract Mapping Editor and XSD Schema

Mapping Input Fields to the Output Fields

Examples

Reading lists

Solution

Reading variants

Solution

Best Practices

Compatibility

See also