CODEWITHSUNDEEP
javacamundabpmn.io
user6438693
user6438693

Reputation:

How to retrieve process variable in Camunda-bpm?

While reading (https://docs.camunda.org/manual/7.5/user-guide/process-engine/variables/) I am not sure how you retrieve a variable?

At the moment I am struggling to find out how to access previously set process variables. What I tried is:

I have a simple bpmn process in which i have start event, 1 service task and end event, I am starting my process by passing 2 variables (a&b) and my service task is implementing following java class:

public class Addition implements JavaDelegate {

    public void execute(DelegateExecution exe) throws Exception {

        System.out.println("Inside calculator again");

        Integer x = (Integer) exe.getVariable("a");
        Integer y = (Integer) exe.getVariable("b");
        int add = x+y;
        System.out.println("Addition of two number is"+add);
        exe.setVariable("add",add);
}

I am starting my process as follows:

public void sayHello(ProcessEngine processEngine)
{
    Map<String,Object> variables = new HashMap<String, Object>();
    variables.put("a", 3);
    variables.put("b", 5);
    ProcessInstance instance=  processEngine.getRuntimeService().startProcessInstanceByKey("Process_3", variables);
}

I want to access add variable (present in Addition class) in sayHello class? As process has been completed so I can't use runtimeService so I tried to use history service but couldn't find out any solution.

Is there any Java API which I can use or is there any other way?

Upvotes: 1

Views: 8288

Answers (3)

Abe
Abe

Reputation: 706

I use flowable. I have no problem to get those processInstance level variables. They are at root level. All the execution, taskservice, javaDelegate can get them out. I guess it is same for camunda.

select * from ACT_RU_VARIABLE

//to set

ProcessInstance processInstance = runtimeService.createProcessInstanceBuilder().processDefinitionKey(key)
        .variable(AppConstants.TENANT_ID, tenantId)
        .variable(AppConstants.CONSUMER_ID, consumerId)
        .start();

//from taskService

    Task currentTask = taskService.createTaskQuery().processInstanceId(processInstanceId).singleResult();
    var testVariable = taskService.getVariables(currentTask.getId());

//from JavaDelegate

public class notificationService implements JavaDelegate {

    @Override
    public void execute(DelegateExecution execution) {

        Map<String, Object> variables = execution.getVariables();
        String str = variables.get(AppConstants.TENANT_ID) + " "
                + variables.get(AppConstants.CONSUMER_ID) + " "
                + execution.getProcessInstanceId();

Upvotes: 0

chekkal
chekkal

Reputation: 307

for anyone struggling with the same issue the variables used to start the process are process variables, the ones we retrieve via delegate are local ones so you have to somehow get to the process instance. To make your code works I'll rewrite it as follow (will change from implementing JavaDelegate to implementing ActivityBehavior and to get the variable you have to go througth call to getParent()).

public class Addition implements ActivityBehavior{

    public void execute(ActivityExecution exe) throws Exception {

        System.out.println("Inside calculator again");

        int x = (int) exe.getParent().getVariable("a");
        int y = (int) exe.getParent().getVariable("b");
        int add = x+y;
        System.out.println("Addition of two number is: " + add);
        exe.setVariable("add",add);

}

The sayHello method won't change

public void sayHello(ProcessEngine processEngine)
{
    Map<String,Object> variables = new HashMap<String, Object>();
    variables.put("a", 3);
    variables.put("b", 5);
    ProcessInstance instance= 
    processEngine.getRuntimeService().startProcessInstanceByKey("Process_3", variables);
 }

Upvotes: 0

Zelldon
Zelldon

Reputation: 5516

If you want to get all historic variable instances use the list method in the HistoricVariableInstanceQuery.

For Example 

List<HistoricVariableInstance> variables = processEngine.getHistoryService().createHistoricVariableInstanceQuery.list();

If you want to get specific variables with the given name you can use the method variableName(String)

For Example:

List<HistoricVariableInstance> variables = processEngine.getHistoryService().createHistoricVariableInstanceQuery().variableName("myVar").list();

To get the variables of a specific process instance use the method processInstanceId

For Example:

 List<HistoricVariableInstance> variables = processEngine.getHistoryService().createHistoricVariableInstanceQuery().processInstanceId(processInstance.getId()).variableName("myVar").list();

See for further information the documentation of the HistoryService and HistoricVariableInstanceQuery

Upvotes: 4

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