[SalesForce] Does doInit() event fire when the attribute values change in a lightning component

I have a parent component which has a child component. The child component has an init action which basically sets the body of the child component. But this is in turn dependent on the child component attributes which reset based on the parent component attributes. SO my question here is the action I am calling on init needs to be called after all the child component attributes have been set correctly from the parent attribute. What is the best way of firing this action? Does attribute change re-trigger init action? If not I need to find a different way of setting the body.

Also, previously I was creating this child component dynamically after all the parent component attributes were reading. But again I needed to fire something on the parent component based on the click of a button inside the child. I couldn't make it happen since the event fired from my dynamically created child component was not being captured by the parent.

Best Answer

You could handle that value change in the controller by defining a 'change' handler, then the framework will do the rerender of the component.

You have more info here.

Related Solutions

[SalesForce] Lightning Components – SObject attribute change event only sent to descendants

Thanks Bob.

I can confirm the issue you are reporting: change handlers are not fired up the chain when members of attribute type "object" are modified. Here is a workaround:

Change:

component.set('v.acc.Name', 'Name from 3!');

To:

var acc = component.get('v.acc');
acc.Name = 'Name from 3!';
component.set('v.acc', acc);

And everything will work.

Here is why you are seeing this behavior, and why the workaround is working:

The rule to remember: all changes are propagated down, but only propagated up when they affect the root of the attribute.
About the workaround: because component.get('v.acc') is returning a pointer to the object (this is JavaScript after all), we are not not copying the data, and it is not less efficient than calling component.get('v.acc.Name'). Sure it is more verbose, but not less efficient!

[SalesForce] Lightning Components – Are passed in attributes available to the init method

init event of the child component will called long before the parent's. Add aura:doneRendering event in the child component and access the list in in the child. Order in which init fired is mentioned in the developer guide and in this article too.

When the component tree is ready, the init event is fired for all the components, starting from the children component and finishing in the parent component.

Beware aura:doneRendering will be called multiple times as part of the component lifecycle, when the aura:attributes are dirty. So have a aura:attribute which serves as a flag to help, you decide whether to process the logic.

Best Answer

Related Solutions

[SalesForce] Lightning Components – SObject attribute change event only sent to descendants

[SalesForce] Lightning Components – Are passed in attributes available to the init method

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