The Schema Validation filter validates XML inputs against an XSD schema. It is commonly placed at the start of a Mule flow to determine if the incoming message should be handled. If validation fails, the message will not continue in the flow. This filter returns a true or false based on validation and can be wrapped in a message filter to throw exceptions or route to another flow if validation fails. The returnResult parameter controls whether the XML payload is retained if validation passes.

1. Ankit Lawaniya
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2. The Schema Validation filter takes XML inputs and validates these against a
referenced XSD schema. Typically, we’ll place it at the start of the Mule flow
to determine whether the incoming message or event should be handled or
not, allowing the message to only continue on along the flow when the filter
validations are met and the included XML is considered valid. Schema
Validator is provided out of the box with Mule.
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3. A common use case in Mule ESB flows is validating if an XML document is
valid against a corresponding XSD, so we can make sure we are receiving the
correct XML, and will forward it for the further processing.
Syntax:
<mulexml:schema-validation-filter
schemaLocations="src/main/resources/File/Process/Schema.xsd"
returnResult="true" name="OrderData_Schema_Validation"
doc:name="Schema Validation" />
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4. The "standard" way of Validating XML schema in Mule is by using the
schema-validation-filter and especially in combination with the message-
filter.
In a case when you want to get an exception and/or call another flow when
the validation fails, you could wrap the schema validation filter inside a
message filter and then use "onUnaccepted" and "throwOnUnaccepted"
configuration attributes to determine the behavior.
Here we have wrapped the schema-validation-filter in a message-filter and
set throwOnUnaccepted to "true.“
<message-filter throwOnUnaccepted="true" >
<mulexml:schema-validation-filter
schemaLocations="/File/Process/Schema.xsd" returnResult="true"
name="OrderData_Schema_Validation"
doc:name="Schema Validation" />
</message-filter>
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5. In order to allow a valid XML to pass the filter, you need to set the
returnResult to false in your schema-validation-filter. This way, the payload
of the message that is passed onwards to the next element in your flow will
retain the XML content.
Let’s walk through how to use All Validator in a Mule application. In this
example, we are receiving the XML file through file connector, which will be
validated against an XSD schema file defined in the application. If validation
fails, then we catch the exception and print the "Schema Not Validated"
message along with the exception.
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10. Now in the XSD XML if we change the any of the element against the schema defined ,we
will be getting the below exception.
ERROR 2017-08-08 21:01:19,585 [[schemavalidation1].SchemaValidationFLow.stage1.02]
org.mule.exception.CatchMessagingExceptionStrategy:
********************************************************************************
Message : Message has been rejected by filter.
Filter : org.mule.module.xml.filters.SchemaValidationFilter@39c5e4bb (null)
Payload : <?xml version="1.0" encoding="UTF-8"?>
Element XML : <message-filter throwOnUnaccepted="true" doc:name="Message">
<mulexml:schema-validation-filter
schemaLocations="src/main/resources/File/Process/Schema.xsd" returnResult="true"
name="OrderData_Schema_Validation" doc:name="Schema Validation"></mulexml:schema-
validation-filter>
</message-filter>
Payload Type : org.apache.xerces.dom.DocumentImpl
Element : /SchemaValidationFLow/processors/2 @
schemavalidation1:schemavalidation1.xml:23 (Message)
--------------------------------------------------------------------------------
Root Exception stack trace:
org.mule.api.routing.filter.FilterUnacceptedException: Message has been rejected by filter.
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