VariableScope#getVariables

[etienne]

Hi

I've gone through the implementation of org.activiti.engine.delegate.VariableScope#getVariables and the following question came up: if the same name is used for a variable on different scopes in the scope hierarchy, why does the variable furthest up the tree have precedence? Intuitively, I would have imagined that a more 'local' scope has precedence.

This is the code I mean:

for (VariableInstanceEntity variableInstance: variableInstances.values()) {
variables.put(variableInstance.getName(), variableInstance.getValue());
}
VariableScopeImpl parentScope = getParentVariableScope();
if (parentScope!=null) {
return parentScope.collectVariables(variables);
}

Thanks for sharing the thoughts behind this implementation 'strategy'.

Regards, Etienne

[jbarrez]

When I look at the getVariable(String) code, it is clear that the closest in the tree is returned (see first if). Only when the variableInstance is null, the tree is searched upwards.

public Object getVariable(String variableName) {
    ensureVariableInstancesInitialized();
    VariableInstanceEntity variableInstance = variableInstances.get(variableName);
    if (variableInstance!=null) {
      return variableInstance.getValue();
    }
    VariableScope parentScope = getParentVariableScope();
    if (parentScope!=null) {
      return parentScope.getVariable(variableName);
    }
    return null;
  }
Where is the code you pasted coming from?

[etienne]

VariableScopeImpl, line 77:

protected Map<String, Object> collectVariables(HashMap<String, Object> variables) {
    ensureVariableInstancesInitialized();
    for (VariableInstanceEntity variableInstance: variableInstances.values()) {
      variables.put(variableInstance.getName(), variableInstance.getValue());
    }
    VariableScopeImpl parentScope = getParentVariableScope();
    if (parentScope!=null) {
      return parentScope.collectVariables(variables);
    }
    return variables;
  }

And that's part of my confusion: getVariable() will return a local variable first, even in case of a name clash, but getVariables() will have non-local variables "win" in case of a name clash.

Regards, Etienne

[trademak]

Hi,

I've committed a fix for this (in two iterations).
At first I couldn't find a test case where it went wrong. But then I stumbled upon the GetExecutionVariablesCmd, which only used the variable names out of the collectVariables method.
So that's the reason it still executed without any errors. I refactored the GetExecutionVariablesCmd command so that it also uses the variable values and then the order of the local and parent variable retrieval does matter.

Thanks,

[etienne]

Hi Tijs

Cool. Thank you.

Regards, Etienne