Validating Documents against an XSD Schema with the XML Module - Mule 4

The <xml-module:validate-schema> operation validates that the input content is compliant with a given schema. This operation supports referencing many schemas (using comma as a separator) that include each other.

This example shows how to work with XML that contains the script of the play Othello by William Shakespeare. The XML file looks something like this:

<flow name="process">
    <xml-module:validate-schema schemas="schema1.xsd, schema2.xsd" />
    <flow-ref name="processValidDocument" />
</flow>

By default, this operation looks for the input document at the message payload level. However, you can supply your own input, for example:

<flow name="process">
    <file:read path="document.xml" target="xmlDoc" />
    <xml-module:validate-schema schemas="schema1.xsd, schema2.xsd">
        <xml-module:content>#[vars.xmlDoc]</xml-module:content>
    </xml:module:validate-schema>
    <flow-ref name="processValidDocument" />
</flow>

Note that you can use the <xml-module:validate-schema> component inside a <validation:all> element.

Handling the Validation Error

If the validation is successful, nothing happens, and the flow continues to the next operation. If it fails, an XML-MODULE:SCHEMA_NOT_HONOURED error is raised.

The XML-MODULE:SCHEMA_NOT_HONOURED error is a complex one. Because the validation can fail for any number of reasons, the error contains a list of Messages. Each message contains a SchemaViolation object, which has the following structure:

SchemaViolation Object

{
  lineNumber: Number,
  columnNumber: Number,
  description: String
}

Consider the following example:

 <flow name="extractErrorsFromException">
    <try>
        <xml-module:validate-schema schemas="schema.xsd" /> (1)
        <error-handler>
            <on-error-propagate type="XML-MODULE:SCHEMA_NOT_HONOURED"> (2)
                <foreach collection="#[error.errorMessage.payload]">
                    <logger level="ERROR" message="#['At line: $(payload.lineNumber), column: $(payload.columnNumber) -> $(payload.description)']" /> (3)
                </foreach>
            </on-error-propagate>
        </error-handler>
    </try>
</flow>

ERROR 2018-02-16 14:35:45,722 [[MuleRuntime].cpuIntensive.01: [SchemaValidationTestCase#extractErrorsUsingExpressions].extractErrorsFromException.CPU_INTENSIVE @411e886b] org.mule.runtime.core.internal.processor.LoggerMessageProcessor: At line: -1, column: -1 -> cvc-complex-type.2.4.a: Invalid content was found starting with element 'fail'. One of '{used}' is expected.