计算可观察值未更新 UI

Question

我的挖空网中的计算变量有问题。这是我的代码：

function ViewModel() {
    var self = this;
    self.seatsRaw = ko.observableArray([]);
    self.selectedSeatId = ko.observable();
    self.session = ko.observable();
    self.seats = ko.computed(function(){
        var seatsComplete= self.seatsRaw().slice(0);
        for (var i = 0; i < seatsComplete.length; i++) {
            if (self.selectedSeatId()) {
                seatsComplete[i].selected = seatsComplete[i].id == self.selectedSeatId();
            } else if (self.session () && Number(self.session ().seat) > 0) {
                seatsComplete[i].selected = seatsComplete[i].id == self.sesion().seat;
            } else {
                seatsComplete[i].selected = false;
            }
        }
        return seatsComplete;
    });
    self.selectSeat = function(data,event) {
    self.selectedSeatId($(this).id);
    };
}

所以，我刚收到一个带座位的数组，我想为数组中的每个 object 添加一个字段，以在 UI 中显示为 "selected"。

我从 ajax 中读取了 session 的信息和原始座位，当我更新它们时，我的 UI.

没有看到任何变化

为什么会这样？然后，我需要做什么来更新我的 UI?

谢谢！

编辑

<ul class="seats" data-bind="foreach: seats">
      <li data-bind="css: {selected: selected, 'non-selected': !selected}, click: $root.selectSeat">
       <a href="#" data-bind="attr: {id: id}">
            <img data-bind="attr: {src: baseUrl + 'img/seats/' + image}" />
            <p data-bind="text: name"></p>
       </a>
      </li>
 </ul>

Seat 不是 ViewModel...应该是吗？

Answer 1

感谢您提供一些额外的背景信息。我会尝试更好地解释我在评论中的意思。

Seat is not a ViewModel... should it be?

即使 Seat 只是一个普通对象，它也是一种视图模型...这是您的代码中发生的事情（据我所知）：

当您在计算中创建新数组时，它会填充与先前数组相同的对象。剔除渲染器看不到重新渲染列表项的理由。

看看这个例子。从日志中您可以看到所有内容 "working correctly"，但敲除不会更新。在这个例子之后，我将展示如果我们让 selected 可观察会发生什么。

var seats =[
  { id: 1, selected: false },
  { id: 2, selected: true },
  { id: 3, selected: false }
];

var ViewModel = function() {
  var self = this;
  this.rawSeats = ko.observableArray(seats);
  
  this.selectedSeatId = ko.observable(2);
  this.selectSeat = function(data, event) {
    self.selectedSeatId(data.id)
  }
  
  this.seats = ko.computed(function() {
    var selectedId = self.selectedSeatId();
    self.rawSeats().forEach(function(seat) {
      seat.selected = seat.id === selectedId;
    })
    
    console.log(self.rawSeats());
    return self.rawSeats();
    
  });
  
  }

ko.applyBindings(new ViewModel());

.selected { background: yellow }

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<ul data-bind="foreach: seats">
  <li data-bind="css: { selected: selected }, 
                 text: id,
                 click: $root.selectSeat"></li>
</ul>

现在，具有可观察的属性：

var seats =[
  { id: 1, selected: ko.observable(false) },
  { id: 2, selected: ko.observable(true) },
  { id: 3, selected: ko.observable(false) }
];

var ViewModel = function() {
  var self = this;
  this.rawSeats = ko.observableArray(seats);
  
  this.selectedSeatId = ko.observable(2);
  this.selectSeat = function(data, event) {
    self.selectedSeatId(data.id)
  }
  
  this.seats = ko.computed(function() {
    var selectedId = self.selectedSeatId();
    self.rawSeats().forEach(function(seat) {
      seat.selected(seat.id === selectedId);
    })
    
    return self.rawSeats();
    
  });
  
  }

ko.applyBindings(new ViewModel());

.selected { background: yellow }

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<ul data-bind="foreach: seats">
  <li data-bind="css: { selected: selected }, 
                 text: id,
                 click: $root.selectSeat"></li>
</ul>

计算可观察值未更新 UI

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