AttributeChanged callback not firing with 0.2.3

[akhile...@gmail.com]

Did anything change in the Polymer API for attributeChanged callback? With 0.2.3, attributeChanged is not getting called whenever a property changes on the element. Strongly typed observers are getting called though. Check out this sample: http://jsbin.com/kucuqete/1/edit

Am I missing something obvious? This used to work till 0.2.2.

[Rob Dodson]

One of my students mentioned this today. Going to double check when I get home

On May 5, 2014 7:15 PM, <akhile...@gmail.com> wrote:

Did anything change in the Polymer API for attributeChanged callback? With 0.2.3, attributeChanged is not getting called whenever a property changes on the element. Strongly typed observers are getting called though. Check out this sample: http://jsbin.com/kucuqete/1/edit

Am I missing something obvious? This used to work till 0.2.2.

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[Scott Miles]

Published properties are no longer reflected back to attributes by default, see the notes here: https://github.com/Polymer/polymer/releases/tag/0.2.3.

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[Eric Bidelman]

Demo: http://jsbin.com/kucuqete/2/edit

Sorry about this. We need to get it documented!

https://github.com/Polymer/docs/issues/402

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[akhile...@gmail.com]

Oh ok. Yeah I saw that change in 0.2.3 release notes but somehow didn't realize that it will impact callback methods too. 

I somehow feel though that the reflection of values should be default on, while opt out should be an option too. I understand there's probably some performance impact, not sure how big, but having default off is slightly un-intuitive and inspecting DOM during debug process gets harder too. May be other option is to just have a global reflect property that could be set/unset for debugging purposes.

One of the cases where I ran into this was in a child element that wants to watch changes to all attributes of a parent element. What's the best way to achieve this in a way such that the child callback always happens no matter how the change watcher is defined on parent for the attributes? i was using attributeChanged callback method on the child, but I think that's not the best way because attributeChanged won't be called if a more specific observer is defined for an attribute by the parent. May be, in the child element, I should attach another Object observer to the instance to watch for specific changes.

[John Messerly]

On Tue, May 6, 2014 at 5:36 PM, <akhile...@gmail.com> wrote:

Oh ok. Yeah I saw that change in 0.2.3 release notes but somehow didn't realize that it will impact callback methods too. 

I somehow feel though that the reflection of values should be default on, while opt out should be an option too. I understand there's probably some performance impact, not sure how big, but having default off is slightly un-intuitive and inspecting DOM during debug process gets harder too. May be other option is to just have a global reflect property that could be set/unset for debugging purposes.

One of the cases where I ran into this was in a child element that wants to watch changes to all attributes of a parent element. What's the best way to achieve this in a way such that the child callback always happens no matter how the change watcher is defined on parent for the attributes? i was using attributeChanged callback method on the child, but I think that's not the best way because attributeChanged won't be called if a more specific observer is defined for an attribute by the parent. May be, in the child element, I should attach another Object observer to the instance to watch for specific changes.

https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver is good for watching HTML attribute changes.

 

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