How to configure connector to use serialized object as request body in json format in post request

Camunda 7 Topics Discussion & Questions
1

I have set default-serialization-format: application/json.
Inside java code I am building a request object and passing it as variable to camunda process. I have a service task where I have configured http-connector to call external rest service. I am not able to pass the saved java object as json body in post request.

Request request = new Request();
ProcessInstanceWithVariables processVariableInReturn
 =processEngine.getRuntimeService()
.createProcessInstanceByKey(PROCESS_DEFINITION_KEY)
.setVariable("request", request)
.executeWithVariablesInReturn();

I got ClassCastException:

java.lang.ClassCastException: org.camunda.spin.impl.json.jackson.JacksonJsonNode cannot be cast to java.lang.String

Connector config for post call:

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2

You need to convert your payload into a JSON string. JSON.Stringify(...)

3

I have added JSON.stringify(...)

var obj = execution.getVariableTyped("request");
JSON.stringify(obj.getValueSerialized());

Again same exception: java.lang.ClassCastException: org.camunda.spin.impl.json.jackson.JacksonJsonNode cannot be cast to java.lang.String

I believe obj.getValueSerialized() is not even evaluated. Method getValueSeralized() may not be available in script context.

4

You stringify the Spin variable. JSON.stringify(S(…))

5

Getting the same exception.

Is there any document on configuring the http-connector in detail? There are some examples on git but they are very basic examples.

6

Try this.

List names = new ArrayList();
names.add(“Johann Cruyff”);
names.add(“Franz Beckenbauer”);
names.add(“Gerd Muller”);

	ObjectValue batchesDataValue = Variables.objectValue(names)
            .serializationDataFormat(Variables.SerializationDataFormats.JSON)
            .create();
	
	execution.setVariable("AVAILABLE_NAMES",   batchesDataValue);
7

@Kamalakar_Kale what is your Request object? Do you have a Jackson mapper assignment for a JsonCreator?

Camunda and Camunda SPIN S() uses Jackson.

So here is a example:

Where the “UserDocument” is using:

The S() is just a helper to use instead of a custom mapping.

What you want to read about is how camunda does serialization https://docs.camunda.org/manual/7.10/user-guide/data-formats/data-formats-in-processes/.

HttpConnector is just a wrapper around Apache HTTP Client. the payload field is just a String value which is JSON string.

8

I don’t have any problem in serializing a variable.
I have set the default serialization format to application/json. I can see that variable is saved in the h2 database in ACT_GE_BYTEARRAY table. The problem is when I try to read the same variable inside http-connector configuration, I am not able to convert it to string. Variable that I am getting in connector config is of type JacksonJsonNode node and not a java object type that I have used to create initially.
May be while creating a payload via script , I have used a wrong API to get variable value from execution context.

9