Mule: How Access Field in Pojo From JSON To Object - mule

Question

I building Mule project who receive JSON by HTTPComponent and convet to object.
My problem is can't acess field in object converted.
My flux's XML is:
<flow name="RestJsonHelloWorldFlow1" doc:name="RestJsonHelloWorldFlow1"><http:inbound-endpointexchange-pattern="request-response"
host="localhost" port="8081"
path="credit/new" doc:name="HTTP"
mimeType="application/json"/> <response>
<logger message=" #[message.payload.transactionCode]" level="INFO" doc:name="Logger"/>
</response>
<json:json-to-object-transformer doc:name="JSON to Object" returnClass="com.creditmobile.domain.Request" name="request"/></flow>
My pojo is:
#JsonAutoDetect
public class Request {
private Integer transactionCode;
public Request() {
super();
}
public Integer getTransactionCode() {
return transactionCode;
}
My JSON is:
{
"transactionCode": 1
}
I got following exception:
org.mule.api.transformer.TransformerMessagingException: The object transformed is of type: "SimpleDataType{type=java.lang.String, mimeType='*/*'}", but the expected return type is "SimpleDataType{type=org.mule.api.transport.OutputHandler, mimeType='application/json'}". The current MuleMessage is null! Please report this to dev#mule.codehaus.org
at org.mule.transformer.AbstractMessageTransformer.checkReturnClass(AbstractMessageTransformer.java:183)
at org.mule.transformer.AbstractMessageTransformer.transform(AbstractMessageTransformer.java:162)
at org.mule.transformer.AbstractMessageTransformer.transform(AbstractMessageTransformer.java:73)
+ 3 more (set debug level logging or '-Dmule.verbose.exceptions=true' for everything)
I saw anothers topics with same problem, but they don't have resolution and yours suggesttion doesn't work for me.
I access field with:[message.payload.transactionCode]
Thanks.

Answer 1

I think your problem is in the http response phase, not in accessing the field. Mule gets confused when you try to return your Java object as an http response. Depending on your requirements, try setting the return payload to something more understandable in the response phase. For example
<set-payload value="#[payload.transactionCode.toString()]"/>
or
<json:object-to-json-transformer/>

Answer 2

What do you actually want to return to the user once the application exits RestJsonHelloWorldFlow1 flow?
I think as Anton Kupias said your problem is the tag. I managed to solve the exception by removing the tag, and convert the payload into an object exactly after the HTTP inbound endpoint.
Config XML
<flow name="RestJsonHelloWorldFlow1" doc:name="RestJsonHelloWorldFlow1">
<http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8081" path="credit/new"
doc:name="HTTP" mimeType="application/json" />
<json:json-to-object-transformer
doc:name="JSON to Object" returnClass="com.creditmobile.domain.Request" />
<component class="com.creditmobile.domain.TransactionResponse" doc:name="Java"/>
<object-to-string-transformer doc:name="Object to String"/>
</flow>
basically you have
1) An HTTP inbound endpoint which is set to request-response
2) immediately convert the JSON to Object
3) Then I have created a java component to perform the required processing; by creating a class which implements org.mule.api.lifecycle.Callable. Got the transaction code from the payload and set the overridden method to return an object of type string
public class TransactionResponse implements Callable {
#Override
public Object onCall(MuleEventContext eventContext) throws Exception {
// Type casts payload to object Request
Request requestObject = (Request) eventContext.getMessage().getPayload();
int code = Integer.valueOf(requestObject.getTransactionCode());
String reply = "";
switch (code) {
case 1:
reply = "New";
break;
case 2:
reply = "Delete";
break;
}
return reply;
}
}
4) Then i terminated the flow by adding the Object to String component, Or place the Object to JSON component if you wish to return a JSON object to the user.