I understand the advantages and disadvantages of Aurelia's custom elements vs. <compose>
; Jeremy Danyow's blog post helps. But, I would like to have my cake and eat it too.
I would like to create custom elements that I can also compose dynamically. Since <compose>
requires a different instantiation, to use it would mean that I would need to create two parallel versions of each element -- one for <compose>
and one for static calls. For example, consider the following use case:
<template>
<h1>Welcome to the Data Entry Screen</h1>
<!-- Static controls -->
<my-textbox label="Your name:" value.bind="entry_name"></my-textbox>
<my-datepicker label="Current date:" value.bind="entry_date"></my-datepicker>
<!-- Loop through dynamic form controls -->
<div class="form-group" repeat.for="control of controls" if.bind="control.type !== 'hidden'">
<label class="control-label">${control.label}</label>
<div>
<compose containerless class="form-control"
view-model="resources/elements/${control.type}/${control.type}"
model.bind="{'control': control, 'model': model, 'readonly': readonly}">
</compose>
</div>
</div>
</template>
With the following controls data:
controls = [
{label: 'Entry Date', type: 'my-datepicker', bind: 'acc_entry_date'},
{label: 'Code', type: 'my-textbox', bind: 'acc_entry_code'},
{label: 'Ref', type: 'my-textbox', bind: 'acc_entry_ref'},
{label: 'Description', type: 'my-textarea', rows: '3', bind: 'acc_entry_description'},
{label: 'Status', type: 'my-dropdown', bind: 'acc_entry_status', enum: 'AccountEntryStatus'},
{type: 'hidden', bind: 'acc_entry_period_id'}];
As you can see, I would like to use <my-textbox>
and <my-datepicker>
both statically and dynamically. Custom elements definitely seem like the best approach. However, I don't see how to accomplish this without creating two parallel components -- one designed as a custom element and one designed as a composable view/viewmodel.
How about this for a solution? In my solution, both controls basically are the same, but in a real solution, they would have different behavior, but this is a nice starting point.
Here's an example: https://gist.run?id=e6e980a88d7e33aba130ef91f55df9dd
app.html
<template>
<require from="./text-box"></require>
<require from="./date-picker"></require>
<div>
Text Box
<text-box value.bind="text"></text-box>
</div>
<div>
Date Picker
<date-picker value.bind="date"></date-picker>
</div>
<button click.trigger="reset()">Reset controls</button>
<div>
Dynamic controls:
<div repeat.for="control of controls">
${control.label}
<compose view-model="./${control.type}" model.bind="control.model" ></compose>
<div>
control.model.value = ${control.model.value}
</div>
</div>
</div>
<button click.trigger="changeModelDotValueOnTextBox()">Change model.value on text box</button>
<button click.trigger="changeModelOnTextBox()">Change model.value on text box and then make a copy of the model</button>
</template>
app.js
export class App {
text = 'This is some text';
date = '2017-02-28';
controls = getDefaultControls();
reset() {
this.controls = getDefaultControls();
}
changeModelOnTextBox() {
this.controls[1].model = {
value: 'I changed the model to something else!'
};
}
changeModelDotValueOnTextBox() {
this.controls[1].model.value = 'I changed the model!';
}
}
function getDefaultControls(){
return[
{label: 'Entry Date', type: 'date-picker', model: { value: '2017-01-01' }},
{label: 'Code', type: 'text-box', model: { value: 'This is some other text'}}
];
}
date-picker.html
<template>
<input type="date" value.bind="value" />
</template>
date-picker.js
import { inject, bindable, bindingMode, TaskQueue } from 'aurelia-framework';
import { ObserverLocator } from 'aurelia-binding';
@inject(Element, TaskQueue, ObserverLocator)
export class DatePicker {
@bindable({ defaultBindingMode: bindingMode.twoWay }) value;
model = null;
observerSubscription = null;
constructor(el, taskQueue, observerLocator) {
this.el = el;
this.taskQueue = taskQueue;
this.observerLocator = observerLocator;
}
activate(model) {
if(this.observerSubscription) {
this.observerSubscription.dispose();
}
this.model = model;
this.observerSubscription = this.observerLocator.getObserver(this.model, 'value')
.subscribe(() => this.modelValueChanged());
this.hasModel = true;
this.modelValueChanged();
}
detached() {
if(this.observerSubscription) {
this.observerSubscription.dispose();
}
}
modelValueChanged() {
this.guard = true;
this.value = this.model.value;
this.taskQueue.queueMicroTask(() => this.guard = false)
}
valueChanged() {
if(this.guard == false && this.hasModel) {
this.model.value = this.value;
}
}
}
text-box.html
<template>
<input type="text" value.bind="value" />
</template>
text-box.js
import { inject, bindable, bindingMode, TaskQueue } from 'aurelia-framework';
import { ObserverLocator } from 'aurelia-binding';
@inject(Element, TaskQueue, ObserverLocator)
export class TextBox {
@bindable({ defaultBindingMode: bindingMode.twoWay }) value;
model = null;
observerSubscription = null;
constructor(el, taskQueue, observerLocator) {
this.el = el;
this.taskQueue = taskQueue;
this.observerLocator = observerLocator;
}
activate(model) {
if(this.observerSubscription) {
this.observerSubscription.dispose();
}
this.model = model;
this.observerSubscription = this.observerLocator.getObserver(this.model, 'value')
.subscribe(() => this.modelValueChanged());
this.hasModel = true;
this.modelValueChanged();
}
detached() {
if(this.observerSubscription) {
this.observerSubscription.dispose();
}
}
modelValueChanged() {
this.guard = true;
this.value = this.model.value;
this.taskQueue.queueMicroTask(() => this.guard = false)
}
valueChanged() {
if(this.guard == false && this.hasModel) {
this.model.value = this.value;
}
}
}