If Then else Xpath wso2 - if-statement

Question

I have practice to validation alphabet and numeric. i was can validating both of them. but the return was true or false. with fn:matches combine with escape characters regex. can anyone help me to correct my validation.
My Code
<?xml version="1.0" encoding="UTF-8"?>
<api context="/a" name="A" xmlns="http://ws.apache.org/ns/synapse">
<resource methods="POST">
<inSequence>
<property expression="json-eval($.OperationValueRegex.Value)" name="Value" scope="default" type="STRING"/>
<payloadFactory media-type="xml">
<format>
<OperationValueRegex xmlns="">
<Result1>$1</Result1>
</OperationValueRegex>
</format>
<args>
<arg evaluator="xml" expression="if($ctx:Value != '') then fn:tokenize($ctx:Value, ' ')[matches(., '^\d+$')]" xmlns:fn="http://www.w3.org/2005/xpath-functions"/>
</args>
</payloadFactory>
<respond/>
</inSequence>
<outSequence/>
<faultSequence/>
</resource>
</api>
Expected Result : when not input was not number there was new tag xml for description error
Sample Request:
{
"OperationValueRegex" : {
"Value" : "sadasdsadasd"
}
}
Result expected
<OperationValueRegex>
<Result1>sadasdsadasd</Result1>
<Status>the input not correct</Status>
</OperationValueRegex>
Thanks

Answer 1

For This requirement, you can use wso2 validate mediator. You can use the below json schema to validate the payload. You need to save this in the registry(use the media type as application/json).
{
"$schema": "http://json-schema.org/draft-04/schema#",
"type": "object",
"properties": {
"OperationValueRegex": {
"type": "object",
"properties": {
"Value": {
"type": "number"
}
},
"required": [
"Value"
]
}
},
"required": [
"OperationValueRegex"
]
}
Then you can use the above json schema to validate the payload using validate mediator and construct the expected payload.
<?xml version="1.0" encoding="UTF-8"?>
<proxy xmlns="http://ws.apache.org/ns/synapse"
name="test"
startOnLoad="true"
statistics="disable"
trace="disable"
transports="http,https">
<target>
<inSequence>
<property expression="json-eval($.OperationValueRegex.Value)"
name="Value"
scope="default"
type="STRING"/>
<validate cache-schema="true">
<schema key="conf:/schema/schema.json"/>
<on-fail>
<payloadFactory media-type="xml">
<format>
<OperationValueRegex xmlns="">
<Result1>$1</Result1>
<Status>the input not correct</Status>
</OperationValueRegex>
</format>
<args>
<arg evaluator="xml" expression="$ctx:Value"/>
</args>
</payloadFactory>
<respond/>
</on-fail>
</validate>
<respond/>
</inSequence>
</target>
<description/>
</proxy>