Set Reader and Writer Configuration Properties

DataWeave provides configuration properties for data formats, such as JSON (application/json), XML (application/xml), and (application/csv). The properties change the behavior of DataWeave readers and writers for those formats. For example, the default separator for a CSV reader is a comma (,). You can use the format’s separator property to specify a different separator for CSV content.

Refer to DataWeave Formats for more details on available reader and writer properties for various data formats.

Use a Writer Property in an Output Directive

The following example shows how to append writer properties to the DataWeave output directive. The script uses indent = false to compress the JSON output into a single line.

DataWeave Script:

%dw 2.0
output application/json indent = false
---
{
	hello : "world",
	bello : "world",
	mello : "world"
}

Output JSON:

{"hello": "world","bello": "world","mello": "world"}

The following examples also append writer configuration properties to the output directive:

Avro example that uses schemaUrl
Excel (XLSX) example that uses header=true
Flat File example that sets a schemaPath
XML example that uses inlineCloseOn="empty" to close any empty XML elements

Use Reader and Writer Properties in DataWeave Functions

The DataWeave read, readUrl, and write functions accept one or more comma-separated property configurations within curly braces.

In the header of the following script, the value of myVar is a read function that inputs an XML sample with an empty child element (<ex1></ex1>). The function passes an XML reader property {nullValueOn: "empty"} that converts the value of the empty element to null.

In the body of the script, a write function accepts the value of myVar as input. The function passes the JSON writer properties {skipNullOn:"objects", writeAttributes:true} to skip the object with the null value (<ex1>null</ex1>) and to write the attribute and value of <ex3 a='greeting'>hello</ex3>.