For Polymer 1.0.0 this worked fine for me
Create a reusable behavior or just add the convertToNumeric() to your Polymer element:
@HtmlImport('app_element.html')
library app_element;
import 'dart:html' as dom;
import 'package:web_components/web_components.dart' show HtmlImport;
import 'package:polymer/polymer.dart';
@behavior
abstract class InputConverterBehavior implements PolymerBase {
@reflectable
void convertToInt(dom.Event e, _) {
final input = (e.target as dom.NumberInputElement);
double value = input.valueAsNumber;
int intValue =
value == value.isInfinite || value.isNaN ? null : value.toInt();
notifyPath(input.attributes['notify-path'], intValue);
}
}
Apply the behavior to your element:
@PolymerRegister('app-element')
class AppElement extends PolymerElement with InputConverterBehavior {
AppElement.created() : super.created();
@property int intValue;
}
In HTML of your element configure the input element:
- bind
value to your property: value="[[intValue]]" so the input element gets updated when the property changes
- set up event notification to call the converter when the value changes
on-input="convertToNumeric" notify-path="intValue" where intValue is the name of the property to update with the numeric value.
<!DOCTYPE html>
<dom-module id='app-element'>
<template>
<style>
input:invalid {
border: 3px solid red;
}
</style>
<input type="number" value="[[intValue]]"
on-input="convertToInt" notify-path="intValue">
<!-- a 2nd element just to demonstrate that 2-way-binding -->
<input type="number" value="[[intValue]]"
on-input="convertToInt" notify-path="intValue">
</template>
</dom-module>
An alternative approach
Create a property as getter/setter:
int _intValue;
@property int get intValue => _intValue;
@reflectable set intValue(value) => convertToInt(value, 'intValue');
Create a behavior or add the function directly to your element
@behavior
abstract class InputConverterBehavior implements PolymerBase {
void convertToInt(value, String propertyPath) {
int result;
if (value == null) {
result = null;
} else if (value is String) {
double doubleValue = double.parse(value, (_) => double.NAN);
result =
doubleValue == doubleValue.isNaN ? null : doubleValue.toInt();
} else if (value is int) {
result = value;
} else if (value is double) {
result =
value == value.isInfinite || value.isNaN ? null : value.toInt();
}
set(propertyPath, result);
}
}
This way you can use the same markup as for text input fields
<input type="number" value="{{intValue::input}}">
or if you want to delay the update of the property until the input field is left
<input type="number" value="{{intValue::change}}">
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