Mule Dataweave - How to set http.status

Question

I want to set to http.status code in Dataweave transformation. For this I am setting http.status on Outbound Property tab using below code:

Outbound Property ===> http.status

%dw 1.0
%output application/java
---
"404" when payload[0] == null
otherwise "200"

But it is not reflected even when payload is null. Can any suggest?

EDIT:

For reference here is the full Dataweave code

<dw:transform-message doc:name="buildResponse">
    <dw:set-payload>
        <![CDATA[%dw 1.0 
        %input payload application/java
        %output application/json
        ---
        {
            "customer": {
                "id": payload[0].ID, 
                "name": payload[0].NAME,
                "age": payload[0].AGE,
                "address": {
                    "line1": payload[0].LINE1,
                    "line2": payload[0].LINE2,
                    "city": payload[0].CITY,
                    "state": payload[0].STATE,
                    "pincode": payload[0].PINCODE
                }
            }
        } when (sizeOf payload) > 0
        otherwise 
        {
            "customer" : "not found"
        }]]>
    </dw:set-payload>
    <dw:set-property propertyName="http.status">
        <![CDATA[%dw 1.0
        %output application/java
        ---
        "404" when (sizeOf payload) == 0
        otherwise "200"]]>
    </dw:set-property>
</dw:transform-message>

Answer 1

Ryan Carter's answer is correct. However, there is a specific answer without storing the original payload into a flow variable.

<dw:transform-message doc:name="buildResponse">
    <dw:set-payload>
        <![CDATA[%dw 1.0 
        %input payload application/java
        %output application/json
        ---
        {
            "customer": {
                "id": payload[0].ID, 
                "name": payload[0].NAME,
                "age": payload[0].AGE,
                "address": {
                    "line1": payload[0].LINE1,
                    "line2": payload[0].LINE2,
                    "city": payload[0].CITY,
                    "state": payload[0].STATE,
                    "pincode": payload[0].PINCODE
                }
            }
        } when (sizeOf payload) > 0
        otherwise 
        {
            "customer" : "not found"
        }]]>
    </dw:set-payload>
    <dw:set-property propertyName="http.status">
        <![CDATA[%dw 1.0
        %output application/java
        ---
        "404" when payload.customer == "not found"
        otherwise "200"]]>
    </dw:set-property>
</dw:transform-message>

I did like this: "404" when payload.customer == "not found"

Answer 2

EDIT.

This is because the first part of the dataweave script is overwriting the payload to the JSON. So when you use sizeOf in the set-property dw script it's actually doing a sizeOf the JSON string which is not 0.

To make this work, I would probably store the original payload in a flowVar and use that in the dw script like so:

<http:listener-config name="HTTP_Listener_Configuration"
        host="0.0.0.0" port="8085" doc:name="HTTP Listener Configuration" />
    <flow name="dataweave-testFlow">
        <http:listener config-ref="HTTP_Listener_Configuration"
            path="/test" doc:name="HTTP" />
        <set-payload value="#[[]]" doc:name="Set Payload" />
        <set-variable variableName="originalPayload" value="#[payload]"
            doc:name="Variable" />
        <dw:transform-message doc:name="buildResponse">

            <dw:set-payload>
        <![CDATA[%dw 1.0 
        %input payload application/java
        %output application/json
        ---
        {
            "customer": {
                "id": payload[0].ID, 
                "name": payload[0].NAME,
                "age": payload[0].AGE,
                "address": {
                    "line1": payload[0].LINE1,
                    "line2": payload[0].LINE2,
                    "city": payload[0].CITY,
                    "state": payload[0].STATE,
                    "pincode": payload[0].PINCODE
                }
            }
        } when (sizeOf payload) > 0
        otherwise 
        {
            "customer" : "not found"
        }]]>
            </dw:set-payload>
            <dw:set-property propertyName="http.status">
        <![CDATA[%dw 1.0
        %output application/java
        ---
        "404" when (sizeOf flowVars.originalPayload) == 0
        otherwise "200"]]>
            </dw:set-property>
        </dw:transform-message>
    </flow>

This is a bug with Dataweave in my opinion and created it here: https://www.mulesoft.org/jira/browse/MULE-9021