event.getSource().get() not working after Summer 16 release

Question

Trying to read currently clicked source's title using event.getSource().get("{!v.title}") and set it to the Event attribute. But it is showing me below error.

Action failed: c$AssignedAssessmentListItemToPatient$controller$fireatq [SyntaxError: Invalid key {!v.title}] Failing descriptor: {c$AssignedAssessmentListItemToPatient$controller$fireatq}. Please try again.

It was working fine before Summer 16 release. Please find below code:

fireatq : function(component, event, helper) {
   var action = $A.get("e.c:ATQEvent");
   action.setParams({"AssId" : event.getSource().get("{!v.title}")}
   action.fire();
}

Answer 1

Since Lightning Components Bundle version 39 or above, this seems to have been stable now.

If you have an event like onclick on an HTML tag like <div>, you can use event.currentTarget.

But if the event is for a Lightning Component tag like <lightning:button>, you need to use event.getSource().

This has been well documented in the Event Handling section of Lightning Components Developer guide.

Answer 2

I found that you can assign entire objects and then get them via event.currentTarget. Not sure how long is it going to work for, but works with LS in v40:

<lightning:button
    label="View"
    name="view"
    onclick="{!c.toggleView}"
    variant="{! if(v.state.screen == 'view', 'brand', 'neutral') }"/>


toggleView: function(cmp, event, helper) {
  const view = event.currentTarget.name
  cmp.set('v.state.screen', view)
}

OR

<lightning:button
    label="Foo"
    name="{!v.someObject}"
    onclick="{!c.baz}"/>

baz: function(cmp, event, helper) {
  console.log(event.currentTarget.name)
}

Unsure if this answers your question, but it's a nice and a useful pattern to use.