In wso2 esb how to get a single number(integer) value - wso2

Question

In wso2 ESB after calling an endpoint I am getting the response as number(ex: 78) with header application/json, if without processing the response if i send in out sequence it works fine i'll get the same response. But if I include any mediators for processing in between it'll throw exceptions like Could not save JSON payload. Invalid input stream found. A single string or number is not valid in some cases So, it may throwing the exception but this bug is resolved in wso2 EI 6.2.
So now I am able to process the response but if I use script mediator to get that value it shows {}. If i use json-eval($.) then also i am not able to get the value, also with xpath i am not able to get.
So how to get that response(the value in number) for further processing in wso2 ei, by using script mediator or by using json path.

Answer 1

If you are certain that the response only contains a number with the content-type header with application/json. you can take the value to a property as below.
<property name="RESPONSE_NUMBER" expression="//jsonValue" scope="default" type="INTEGER"/>
When you need this value somewhere else in the mediation flow you can take the value from the property(in this case RESPONSE_NUMBER) as below.
$ctx:RESPONSE_NUMBER
Here is a sample API which demonstrates how you can take the response value and use it in the mediation flow.
<api xmlns="http://ws.apache.org/ns/synapse" name="SampleAPI" context="/getNumber">
<resource methods="GET">
<inSequence>
<send>
<endpoint>
<http method="GET" uri-template="http://www.mocky.io/v2/5b02cc2c3000006600cee384"/>
</endpoint>
</send>
</inSequence>
<outSequence>
<property name="RESPONSE_NUMBER" expression="//jsonValue" scope="default" type="INTEGER"/>
<payloadFactory media-type="json">
<format>{"Id": $1}</format>
<args>
<arg evaluator="xml" expression="$ctx:RESPONSE_NUMBER"/>
</args>
</payloadFactory>
<send/>
</outSequence>
</resource>
</api>
You can call the API with below curl command:
curl -v http://localhost:8280/getNumber