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XML Format

MIME Type: application/xml

ID: xml

The XML data structure is mapped to DataWeave objects that can contain other objects, strings, or null values. XML uses unbounded elements to represent collections, which are mapped to repeated keys in DataWeave objects. In addition, DataWeave natively supports namespaces, CData an xsi:types.

The DataWeave reader for XML input supports the following parsing strategies:

  • Indexed

  • In-Memory

  • Streaming

To understand the parsing strategies that DataWeave readers and writers can apply to this format, see DataWeave Parsing Strategies.

CData Custom Type

CData is a custom DataWeave data type for XML that is used to identify a Character DATA (CDATA) block. The CData type tells the XML writer to wrap content inside a CDATA block or to check for an input string inside a CDATA block. In DataWeave, CData inherits from the type String.

Examples

The following examples show uses of the XML format.

Example: Stream Input XML Data

This example shows how to set up XML streaming, which requires you to specify the following reader properties:

  • streaming=true

  • collectionPath="root.repeated"

The collectionPath setting selects the elements to stream.

When streaming, the XML parser can start processing content without having all the XML content.

Input

The following XML serves as the input payload to the DataWeave source. Assume that it is the content of an XML file myXML.xml.

myXML.xml
<root>
    <text>
        Text
    </text>
    <repeated>
        <user>
            <name>Mariano</name>
            <lastName>de Achaval</lastName>
            <age>36</age>
        </user>
        <user>
            <lastName>Shokida</lastName>
            <name>Leandro</name>
            <age>30</age>
        </user>
        <user>
            <age>29</age>
            <name>Ana</name>
            <lastName>Felissati</lastName>

        </user>
        <user>
            <age>29</age>
            <lastName>Chibana</lastName>
            <name>Christian</name>
        </user>

    </repeated>
</root>

Source

The reader property settings in the DataWeave script tell the XML reader to stream the input and process the repeated keys. The script uses the DataWeave map function to iterate over the repeated keys.

%dw 2.0
var myInput  readUrl('classpath://myXML.xml', 'application/xml', {streaming:true, collectionPath: "root.repeated"})
output application/dw
---
myInput.root.repeated.*user map {
    n: $.name,
    l: $.lastName,
    a: $.age
}

Output

The script transforms the mapped input XML to the DataWeave (dw) format and MIME type.

[
  {
    "n": "Mariano",
    "l": "de Achaval",
    "a": "36"
  },
  {
    "n": "Leandro",
    "l": "Shokida",
    "a": "30"
  },
  {
    "n": "Ana",
    "l": "Felissati",
    "a": "29"
  },
  {
    "n": "Christian",
    "l": "Chibana",
    "a": "29"
  }
]

Example: Null or Empty String in XML

Because there is no standard way to represent a null value in XML, the reader maps the value to null when the nil attribute is set to true.

Input

The following XML serves as the input payload to the DataWeave source. Notice the nil setting in <xsi:nil="true"/>.

<book xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <author xsi:nil="true"/>
</book>

Source

The DataWeave script transforms the input XML to the JSON format and MIME type.

%dw 2.0
output application/json
---
payload

Output

The output is in the JSON format. Notice that the nil value in the input is transformed to null.

{
  "book": {
    "author": null
  }
}

Example: Output null Values for Missing XML Values

The XML reader property nullValueOn accepts the value blank (the default) or empty.

This example uses the nullValueOn default, so it maps the values of the title and author elements to null.

Input

The following XML serves as input to the DataWeave source. Notice that the title and author elements lack values.

Assume that this input is content within the file, myInput.xml.

myXML.xml content:
<book>
    <author></author>
    <title>

</title>
</book>

Source

The DataWeave script transforms the XML input to JSON. Note that it explicitly sets the nullValueOn default, blank, for demonstration purposes.

%dw 2.0
var myInput readUrl('classpath://myXML.xml', 'application/xml', {nullValueOn: "blank"})
output application/json
---
myInput

Output

The title and author keys in the JSON output are assigned null values.

{
  "book": {
    "author": null,
    "title": null
  }
}

Example: Output null Values for Missing XML Values

The XML reader property nullValueOn accepts the value blank (the default) or empty.

The example maps the value of the title element to a String and value of the author element to null because the XML reader property nullValueOn is set to empty.

Input

The following XML serves as input to the DataWeave source. Notice that the title and author elements lack values. The difference between the two elements is the space between the starting and ending tags. The tags of the title element are separated by line breaks (the hidden characters, \n), while the tags of the author element are not separated by any characters.

Assume that this input is content within the file, myInput.xml.

myXML.xml content:
<book>
    <author></author>
    <title>

</title>
</book>

Source

The DataWeave script uses a DataWeave variable to input the content of myXML.xml and applies the nullValueOn: "empty" to it. The script transforms the XML input to JSON.

%dw 2.0
var myInput readUrl('classpath://myXML.xml', 'application/xml', {nullValueOn: "empty"})
output application/json
---
myInput

Output

The JSON output maps the value of the author element to null and value of the title element to the String value "\n\n", which is for the new line characters.

{
  "book": {
    "author": null,
    "title": "\n\n"
  }
}

Example: Represent XML Attributes in the DataWeave (dw) Format

This example maps XML attributes to a canonical DataWeave representation, the application/dw format and MIME type.

Input

The XML serves as the input payload to the DataWeave source. Notice that the input contains XML attributes.

<users>
  <company>MuleSoft</company>
  <user name="Leandro" lastName="Shokida"/>
  <user name="Mariano" lastName="Achaval"/>
</users>

Source

The DataWeave script transforms the XML input payload to the DataWeave (dw) format and MIME type.

%dw 2.0
output application/dw
---
payload

Output

The output shows how the DataWeave (dw) format represents the XML input. Notice how the attributes from the XML input and the empty values are represented.

{
  users: {
    company: "MuleSoft",
    user @(name: "Leandro",lastName: "Shokida"): "",
    user @(name: "Mariano",lastName: "Achaval"): ""
  }
}

Example: Represent XML Namespaces in the DataWeave (dw) Format

This example maps XML namespaces to a canonical DataWeave representation, the application/dw format and MIME type.

Input

The XML serves as the input payload to the DataWeave source. Notice that the input contains XML namespaces.

<root>
    <h:table xmlns:h="http://www.w3.org/TR/html4/">
      <h:tr>
        <h:td>Apples</h:td>
        <h:td>Bananas</h:td>
      </h:tr>
    </h:table>

    <f:table xmlns:f="https://www.w3schools.com/furniture">
      <f:name>African Coffee Table</f:name>
      <f:width>80</f:width>
      <f:length>120</f:length>
    </f:table>
</root>

Source

The DataWeave script transforms the XML input payload to the DataWeave (dw) format and MIME type.

%dw 2.0
output application/dw
---
payload

Output

The output shows how the DataWeave (dw) format represents the XML input. Notice how the namespaces from the XML are represented.

ns h http://www.w3.org/TR/html4/
ns f https://www.w3schools.com/furniture
---
{
  root: {
      h#table: {
        h#tr: {
          h#td: "Apples",
          h#td: "Bananas"
        }
      },
      f#table: {
        f#name: "African Coffee Table",
        f#width: "80",
        f#length: "120"
      }
  }
}

Example: Create a CDATA Element

This example shows how to use the CData type to create a CDATA element in the XML output.

Source

The body of the DataWeave script coerces the String value to the CData type.

%dw 2.0
output application/xml
---
{
    test: "A text <a>" as CData
}

Output

The output encloses the input String value in a CDATA block, which contains the special characters, < and >, from the input.

<?xml version='1.0' encoding='UTF-8'?>
<test><![CDATA[A text <a>]]></test>

Example: Check for CDATA in a String

This example indicates whether a given String value is CDATA.

Input

The XML serves as the input payload to the DataWeave source. Notice that the test element contains a CDATA block.

<?xml version='1.0' encoding='UTF-8'?>
<test><![CDATA[A text <a>]]></test>

Source

The DataWeave script uses the is CData expression to determine whether the String value is CDATA.

%dw 2.0
output application/json
---
{
    test: payload.test is CDATA
}

Output

The JSON output contains the value true, which indicates tha the input String value is CDATA.

{
    "test": true
}

Example: Use the inlineCloseOn Writer Property

This example uses the inlineCloseOn writer property with the value none to act on the key-value pairs from the input.

Source

The DataWeave script transforms the body content to XML. Notice that values of the emptyElement keys are null.

%dw 2.0s
output application/xml inlineCloseOn="none"
---
{
  someXml: {
    parentElement: {
      emptyElement1: null,
      emptyElement2: null,
      emptyElement3: null
    }
  }
}

Output

The emptyElement elements are empty. They do not contain the value null.

<?xml version='1.0' encoding='UTF-8'?>
<someXml>
  <parentElement>
    <emptyElement1></emptyElement1>
    <emptyElement2></emptyElement2>
    <emptyElement3></emptyElement3>
  </parentElement>
</someXml>

Example: Transforms Repeated JSON Keys to Repeated XML Elements

XML encodes collections using repeated (unbounded) elements. DataWeave represents unbounded elements by repeating the same key.

This example shows how to convert the repeated keys in a JSON array of objects into repeated XML elements.

Input

The JSON input serves as the payload to the DataWeave source. Notice that the name keys in the array are repeated.

{
  "friends": [
    {"name": "Mariano"},
    {"name": "Shoki"},
    {"name": "Tomo"},
    {"name": "Ana"}
  ]
}

Source

The DataWeave script selects the value of the friends key.

%dw 2.0
output application/xml
---
friends: {
    (payload.friends)
}

Output

The output represents the name keys as XML elements.

<?xml version='1.0' encoding='UTF-8'?>
<friends>
  <name>Mariano</name>
  <name>Shoki</name>
  <name>Tomo</name>
  <name>Ana</name>
</friends>

Configuration Properties

DataWeave supports the following configuration properties for the XML format.

Reader Properties

The XML format accepts properties that provide instructions for reading input data.

Parameter Type Default Description

collectionPath

String

null

Path to the document where the collection is located. It specifies a path expression that identifies the location of the elements to stream. See Example: Stream Input XML Data.

externalEntities

Boolean

false

Indicates whether external entities should be processed or not. By default this is disabled to avoid XXE attacks. Valid values are true or false.

indexedReader

Boolean

true

Indicates whether to use the indexed XML reader when the threshold is reached. Valid values are true or false.

maxAttributeSize

Number

-1

Sets the maximum number of characters accepted in an XML attribute. Available since Mule 4.2.1.

maxEntityCount

Number

1

The maximum number of entity expansions. The limit is in place to avoid Billion Laughs attacks.

nullValueOn

String

blank

Indicates whether to read an element with empty or blank text as a null value. Valid values are empty, none, or blank. See Example: Output null Values for Missing XML Values and Example: Output null Values for Missing XML Values.

optimizeFor

String

'speed'

Indicates how to configure the XML parser. Valid values are speed and memory.

streaming

Boolean

false

Indicates whether to stream input (use only if entries are accessed sequentially). Valid Options are true or false. See Example: Stream Input XML Data.

supportDtd

Boolean

true

Enable or disable DTD handling. Disabling skips (and does not process) internal and external subsets. Valid Options are true or false.

Writer Properties

The XML format accepts properties that provide instructions for writing output data.

Parameter Type Default Description

bufferSize

Number

8192

Size of the buffer writer.

encoding

String

null

Encoding for the writer to use.

deferred

Boolean

false

Property for deferred output. Valid values are true or false.

escapeCR

Boolean

false

Whether to escape a carriage return (CR). Valid values are true or false. Available since Mule 4.2.1.

indent

Boolean

true

Indicates whether to indent the code for better readability or to compress it into a single line. Valid values are true or false.

inlineCloseOn

String

empty

Indicates when the writer uses inline close tag or use open close tags. Valid values are empty or none.

onInvalidChar

String

null

Valid values are base64, ignore, or none.

skipNullOn

String

null

Skips null values in the specified data structure. By default, the writer does not skip them. Valid values are elements, attributes, or everywhere.

writeDeclaration

Boolean

true

Indicates whether to write the XML header declaration. Valid values are true or false.

writeNilOnNull

Boolean

false

Indicates whether to write a nil attribute when the value is null. Valid values are true or false.

Supported MIME Types

The XML format supports the following MIME types.

MIME Type

*/xml

/+xml

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