Version

    JSONExtract

    Short Description
    Ports
    Metadata
    JSONExtract Attributes
    Details
    Examples
    Best Practices
    Compatibility
    See also

    Short Description

    JSONExtract reads data from JSON files using SAX technology. It can also read data from compressed files, input port, and dictionary.

    ComponentData sourceInput portsOutput portsEach to all outputsDifferent to different outputsTransformationTransf. req.JavaCTLAuto-propagated metadata
    JSONExtractJSON file0-11-n
    no
    yes
    no
    no
    no
    no
    no

    Ports

    Port typeNumberRequiredDescriptionMetadata
    Input0
    no
    		For port reading. See Reading from Input Port.One field (byte, cbyte, string).
    Output0
    yes
    		For correct data recordsAny
    1-n[2]For correct data recordsAny

    [2] 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

    AttributeReqDescriptionPossible values
    Basic
    File URLyes 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 reads lists.

    [Note]Note

    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.

    JSONExtract - mapping the list

    Figure 54.15. JSONExtract - mapping the list


    Best Practices

    We recommend users to explicitly specify Charset.

    Compatibility

    VersionCompatibility Notice
    3.5.0-M2JSONExtract is available since 3.5.0-M2.
    4.1.0-M1You can now map input fields to the output fields in this component.
    4.1.0You can now read lists.