JS API: "changeCustomProperty" notification

Hi, thanks for question

Change event triggers for both change and creation, but customFields and customProperties are diffrent things with diffrent data flags, so first of all you need to decide what do you need

Also check your addListener code

// unit in callback is from parent scope, potential bug here
unit.addListener('changeCustomProperty', function() { update_unit_model(unit); });
// same logic, but more safe
unit.addListener('changeCustomProperty', function(event) { update_unit_model(event.getTarget()); });

More info about qx.event.type.Event

From this side admin field, custom field and custom property are equivalent - they all {name: "", value: ""} dictionaries (first two also has id), but they all used for diffrent purposes

With Wialon you can almost everything

// load library to work with custom fields (including events)
wialon.core.Session.getInstance().loadLibrary("itemCustomFields");
// add "updateCustomField" listener
unit.addListener("updateCustomField", function (e) {
  console.log("Custom field updated", e);
});

I havent seen your code, but common practice is to add listener in loop, something like that

for (var i = 0; i < units.length; i++) {
  unit = units[i];
  unit.addListener('changeMessageParams', function handleChangeMessageParams () {
    console.log(unit);
  });
}

The output of this example in my case - one same unit for different events

cg {$$hash: "28-0", $$user_dataFlags: 1048577, _id: 11996104, $$user_name: "TestObject"…} 
cg {$$hash: "28-0", $$user_dataFlags: 1048577, _id: 11996104, $$user_name: "TestObject"…} 
cg {$$hash: "28-0", $$user_dataFlags: 1048577, _id: 11996104, $$user_name: "TestObject"…} 
cg {$$hash: "28-0", $$user_dataFlags: 1048577, _id: 11996104, $$user_name: "TestObject"…} 

Its the way JS works - it binds function to be called (handleChangeMessageParams), not a data inside it.

So when event triggers, handleChangeMessageParams calls and try to operate with unit variable. Since its not declared in function scope - it will be used from parent scope, where it is equal to last element of units array. To prevent this problem any kind of binding should be used.

Using event.target() makes handling event more comfortable - you'll always be able to get item for which event was triggered

Hope this helps

PS once again, i havent seen your code, and maybe you'll never face such a problem, i just noticed potential hole in your example. But event.getTarget() (and whole event object) can be very usefull when dealing with events, so i decided to tell you about it