Two way binding not working on bootstrap-select with aurelia - aurelia

Question

I have managed to create a custom element to use the boostrap-select element. However, I can pass/bind values to it from the main view (parent) but I am unable to get the selection out from the element when I use two-way binding.
My custom element is:
import {inject, customElement, bindable} from 'aurelia-framework';
import * as selectpicker from 'bootstrap-select'
#customElement('select-picker')
export class BootStrapSelectPicker {
#bindable selectableValues = null;
#bindable newValue = null;
#bindable selectedValue = 10;
constructor(){
}
attached(){
$('.selectpicker').selectpicker({
style: 'btn-info',
size: 4
});
$('.selectpicker').on('change', function(){
var selected = $(this).find("option:selected").val();
this.selectedValue = selected;
console.log(this.selectedValue);
});
$('.selectpicker').val(this.selectedValue); <-- the selection here is correct
$('.selectpicker').selectpicker('refresh');
}
}
The corresponding view is:
<template>
<select class="selectpicker">
<option repeat.for="p of selectableValues">${p}</option>
</select>
</template>
My containing view that uses the custom element is:
<template>
<require from="./select-picker"></require>
<ul class="list-group">
<li class="list-group-item" repeat.for="p of messageProperties">
<div if.bind="p.propertyType == 'string'">
<div class="form-group">
<label for="ln">Name: ${p.propertyName}</label>
<input type="text" value.bind="p.propertyValue" class="form-control" id="ln" >
</div>
</div>
<div if.bind="p.propertyType == 'integer'">
<div class="form-group">
<label for="ln">Name: ${p.propertyName}</label>
<input type="text" value.bind="p.selectedValue" class="form-control" id="ln" >
<select-picker selectable-values.bind="p.selectableValues"
selected-value.two-way="p.selectedValue"></select-picker>
</div>
</div>
</li>
</ul>
</template>
I expected p.selectedValue to change once a selection is made with the select control as shown here with the two-way command:
selected-value.two-way="p.selectedValue"
However, p.selectedValue is not changing.
Any ideas why this is not working?

Answer 1

Turns out to be a simple scope issue:
attached(){
$('.selectpicker').selectpicker({
style: 'btn-info',
size: 4
});
$('.selectpicker').on('change', function(){
var selected = $(this).find("option:selected").val();
this.selectedValue = selected; // <-- This here doesn't refer to the VM any more
// if you look at the line above you are wrapping $(this) with jq, this works
// because 'this' is now in the scope of the calling element but
// doesn't refer to the aurelia viewmodel
console.log(this.selectedValue);
});
$('.selectpicker').val(this.selectedValue);
$('.selectpicker').selectpicker('refresh');
}
Simple fix is:
attached(){
var self = this; // <--- Create a ref to the VM
$('.selectpicker').selectpicker({
style: 'btn-info',
size: 4
});
$('.selectpicker').on('change', function(){
var selected = $(this).find("option:selected").val();
// Change this to self
self.selectedValue = selected; // <--- Correct object gets the value now - binding works
console.log(this.selectedValue);
});
$('.selectpicker').val(this.selectedValue);
$('.selectpicker').selectpicker('refresh');
}
I'm not sure how this will actually be handled in ES6/7 - I'm sure I read somewhere about how this will change, but since you are transpiling to ES5 it's definitely something to watch out for

Answer 2

The following code works for me, in case anyone has the same issue:
import {inject, customElement, bindable} from 'aurelia-framework';
import 'bootstrap-select'
#customElement('select-picker')
#inject(Element)
export class BootStrapSelectPicker {
#bindable name: string;
#bindable selectableValues;
#bindable selectedValue;
constructor(private element) {
}
attached() {
var self = this;
var $: any = jQuery;
var $elm = $(self.element).find('select');
if ($elm.length > 0) {
$elm.selectpicker();
$elm.on('change', function () {
self.selectedValue = $(this).find("option:selected").val();
});
this.refreshPicker($elm);
}
}
selectedValueChanged(newValue, oldValue) {
var $: any = jQuery;
var $elm = $(this.element).find('select');
this.refreshPicker($elm);
}
private refreshPicker = ($elm) => {
$elm.val(this.selectedValue);
$elm.selectpicker('refresh');
}
}