fyi, fix is here:
https://chromiumcodereview.appspot.com/22417004/

we were tracking this in https://github.com/dart-lang/web-ui/issues/508 though :)

edit: fix link

See also https://chromiumcodereview.appspot.com/22417004/

Wonderful, I grabbed the diff from the review site and applied it locally. It works! (fwiw, the patch isn't yet in github's polymer branch)

yeah, we are debating in the code review what the right behavior is if the number fails to parse. Unfortunately polymer.js isn't useful for guidance as they preserve the string (which in Dart wouldn't work, would just cause a checked mode failure)

FWIW this worked:

    <polymer-element name="my-element" attributes="volume,intThing">
      <template>
        <h1>Hello from the custom element. The volume is {{volume}}
        and intThing is {{intThing}}</h1>
      </template>
      <script type="application/dart">
        import 'package:polymer/polymer.dart';
        
        @­CustomTag('my-element')
        class MyElement extends PolymerElement with ObservableMixin {
          @­observable String volume;
          @­observable String intThing;
        }
      </script>
    </polymer-element>
    
    <!-- I don't see "The volume is 11", I just see "The volume is" -->
    
    <my-element volume="11" intThing="42"></my-element>

but this did not:

    <polymer-element name="my-element" attributes="volume,intThing">
      <template>
        <h1>Hello from the custom element. The volume is {{volume}}
        and intThing is {{intThing}}</h1>
      </template>
      <script type="application/dart">
        import 'package:polymer/polymer.dart';
        
        @­CustomTag('my-element')
        class MyElement extends PolymerElement with ObservableMixin {
          @­observable String volume;
          @­observable int intThing;
        }
      </script>
    </polymer-element>
    
    <!-- I don't see "The volume is 11", I just see "The volume is" -->
    
    <my-element volume="11" intThing="42"></my-element>

When I use '@observable int intThing' I get "and intThing is"

However, if I initialize intThing to an integer, like this:

@observable int intThing = 0;

then I get "and intThing is 42"

Sounds like the rule is: if you want to use a type annotation other than String for your field, be sure to initialize it with a default value. I think this matches how polymer.js works.

This comment was originally written by @sethladd

Hi guys,

Is it too late to get this in in time for the next integration build? This is a great feature.

This comment was originally written by joh...@johnmccutchan.com

Is there a way to plugin my own attribute string parse routine for custom types like Color, Vector3, Matrix4, etc?

@john -- yes there most definitely should be!
Polymer has several features that help here:

deserializeValue -- you can override this to provide your own serialization

deserializing JSON -- it attempts to deserialize into JSON by default.

I'm pretty confused about what to do with respect to JSON. We could use json.parse in Dart, and give you maps and lists and primitives and stuff. Or we could try to deserialize into a Dart type. At that point, we'd have to look at type annotations... which suggests maybe we should just take advantage of our type annotations here.

Signed, - A Confused Polymer Porter.

update: leaning towards using type annotations if available, and fall back to the default value's type if no other information is available. This is one place we can lean on the type annotations in Dart to provide a better experience. (and this is how real DOM HTMLElements work, after all -- the property type is specified in the IDL).

Set owner to @jmesserly.
Removed Type-Defect label.
Added Type-Enhancement, Started labels.

Removed Priority-Unassigned label.
Added Priority-High label.

Woot!

Issue #12715 has been merged into this issue.

Added this to the M7 milestone.

Changed the title to: "Custom element, custom attribute, setting to a literal value doesn't work".

Added Polymer-WebUICompat label.

edit subject -- this is now tracking all attribute incompatibilities vs Polymer:

* Setting to a literal value doesn't work

• attributeChanged event does not work
• there is no way to publish from code ("publish:" in JavaScript, probably @­publish in Dart), only "attributes=" on polymer-element is supported
• there may be issues with property binding as well (https://code.google.com/p/dart/issues/detail?id=13152)

Changed the title to: "Polymer.dart attributes are missing features: literals, attributeChanged, case insensitivity".

* also, the dash-separated vs camelCase issue