你可以做的几件事——假设我的用例是正确的:

脏检查(这只是一个属性-没什么大不了的)

export class Item {
  selected = false;
}
export class ViewModel {
  items = [new Item(), new Item(), new Item()];
  get anySelected() {
    var items = this.items, i = items.length;
    while(i--) {
      if (items[i].selected) {
        return true; 
      }
    }
    return false;
  }
}

观察条目

import {BindingEngine, inject} from 'aurelia-framework';
export class Item {
  selected = false;
}
@inject(BindingEngine)
export class ViewModel {
  items = [new Item(), new Item(), new Item()];    
  anySelected = false;
  subscriptions = [];
  constructor(locator) {
    this.bindingEngine = bindingEngine;
  }
  updateAnySelected() {
    var items = this.items, i = items.length;
    while(i--) {
      if (items[i].selected) {
        this.anySelected = true;
        return;
      }
    }
    this.anySelected = false;
  }
  activate() {
    var items = this.items, i = items.length, observer;
    while(i--) {
      observer = this.bindingEngine.propertyObserver(items[i], 'selected');
      subscriptions.push(observer.subscribe(() => this.updateAnySelected());
    }
    this.updateAnySelected();
  }
  deactivate() {
    let dispose;
    while(subscription = subscriptions.pop()) {
      subscription.dispose();
    }
  }
}

使用集合类

import {computedFrom} from 'aurelia-framework';
export class Item {
  _selected = false;
  constructor(parent) {
    this.parent = parent;
  }
  @computedFrom('_selected')
  get selected() {
    return this._selected;
  }
  set selected(newValue) {
    newValue = !!newValue;
    if (newValue === _selected) {
      return;
    }
    _selected = newValue;
    this.parent.itemChanged(newValue);
  }
}
export class Items {
  items = [];
  selectedCount = 0;
  anySelected = false;
  createItem() {
    let item = new Item(this);
    this.items.push(item);
    return item;
  }
  itemChanged(selected) {
    this.selectedCount += (selected ? 1 : -1);
    this.anySelected = this.selectCount > 0;    
  }
}
export class ViewModel {
  items = new Items();
  constructor() {
    let item = this.items.createItem();
    item = this.items.createItem();
    item = this.items.createItem();
  }
}

使用selectedItems数组代替选定的布尔prop

export class ViewModel {
  items = [{}, {}, {}];
  selectedItems = [];
  selectItem(item) {
    this.items.push(item);
  }
  deselectItem(item) {
    this.items.splice(this.items.indexOf(item), 1);
  }
}

用于绑定目的，使用selectedItems.length作为您的"any selected"属性

除了Jeremy的例子，您还可以创建一个自定义setter，例如:

class Item {
   // this is your ~private~ field
  _isSelected = false;
  // in our constructor, we pass the view model and the property name
  constructor(vm, prop, name) {
    this.vm = vm;
    this.prop = prop;
    this.name = name;
  }
  get isSelected() {
    return this._isSelected;
  }
  // when you set the value, you increase the vm's property
  set isSelected(value) {
    if (value !== this._isSelected) {
      this.vm[this.prop] += value ? 1 : -1;
      this._isSelected = value;
    }
  }
}
export class MyViewModel
{
  items = [];
  itemsSelected = 0; // that's the property we'll pass to the class we've created
  constructor() 
  {
    for (let i = 0; i < 50; i++) {
      // instead of adding a annonymous {} here, we add an instance of our class
      this.items.push(new Item(this, 'itemsSelected', `Item ${i+1}`));
    }
  }
  toggleIsSelected(item) {
    item.isSelected = !item.isSelected;
  }
}

我已经为你创建了一个活塞:http://plnkr.co/edit/OTb2RDLZHf5Fy1bVdCB1?p=preview

这样做，您将永远不会循环查看某些项是否已更改。

我认为您也可以利用EventAggregator如图所示。这样就不需要一直执行脏检查，而是在自己的VM中处理项目选择事件并发布eventdata;另一边的订阅者将听同样的内容，并执行所需的体操动作。

然而，我从未使用过它，所以我不确定它的更深层次的细节。但是从文档来看，这看起来很简单。

Jeremy让我在这个bug中思考这个问题。看起来你也可以通过一个自定义的绑定行为获得绑定刷新。希望Jeremy能确认我没有做什么太愚蠢的事情。

像这样使用:

repeat.for="item of items | filter & array:'propertyName'"

它覆盖了标准的观察行为，并观察数组和你在每个项上定义的属性。它可能会被改进成更通用的…

function observeProperty(obj, property) {
  this.standardObserveProperty(obj, property);
  let value = obj[property];
  if (Array.isArray(value)) {
    this.observeArray(value); 
    for(let each of value){   
      this.standardObserveProperty(each, this.propertyName); 
    }
  }
}
export class ArrayBindingBehavior {
  bind(binding, source, property) {
    binding.propertyName = property;
    binding.standardObserveProperty = binding.observeProperty;
    binding.observeProperty = observeProperty;
  }
  unbind(binding, source) {
    binding.observeProperty = binding.standardObserveProperty;
    binding.standardObserveProperty = null;
    delete binding.propertyName;
  }
}