[英]knockout sortable with computed observable not working
jsfiddle示例 。 就像標題所說的那樣,我正在嘗試將計算的可觀察值與rniemeyer剔除可排序示例一起使用。 我不斷
寫方法需要實現
在開發人員控制台中可以看到此錯誤。
我在ko.computed上有一個write方法實現,但仍然出錯。 我做錯了什么?
下面的html和javascript
<div id="main">
<h3>Tasks</h3>
<div class="container" data-bind="sortable: tasks">
<div class="item">
<span data-bind="visible: !$root.isTaskSelected($data)">
<a href="#" data-bind="text: TestName"></a>
</span>
<span data-bind="visibleAndSelect: $root.isTaskSelected($data)">
<input data-bind="value: name, event: { blur: $root.clearTask }" />
</span>
</div>
</div>
</div>
var Task = function(first,last) {
var self = this;
self.firstName = ko.observable(first);
self.lastName = ko.observable(last);
self.TestName = ko.computed({
read: function (){
return self.firstName() + " " + self.lastName();
},
write: function (item) {
console.log(item);
}
});
return self;
}
var ViewModel = function() {
var self = this;
self.testTasks = ko.observableArray([
new Task("test","one"),
new Task("test","two"),
new Task("test","three")
]);
self.tasks = ko.computed({
read: function() { return self.testTasks();},
write: function(item) {console.log(item);}
});
self.selectedTask = ko.observable();
self.clearTask = function(data, event) {
if (data === self.selectedTask()) {
self.selectedTask(null);
}
if (data.name() === "") {
self.tasks.remove(data);
}
};
self.addTask = function() {
var task = new Task("new");
self.selectedTask(task);
self.tasks.push(task);
};
self.isTaskSelected = function(task) {
return task === self.selectedTask();
};
};
//control visibility, give element focus, and select the contents (in order)
ko.bindingHandlers.visibleAndSelect = {
update: function(element, valueAccessor) {
ko.bindingHandlers.visible.update(element, valueAccessor);
if (valueAccessor()) {
setTimeout(function() {
$(element).find("input").focus().select();
}, 0); //new tasks are not in DOM yet
}
}
};
ko.applyBindings(new ViewModel());
作為這個插件的非常作者說在這里 ,你不能使用計算觀察的; sortable插件取決於實際的可觀察數組。
當您考慮它時,這是有道理的:當您對元素進行重新排序時,插件實際上是在操縱數組的各種索引。
如果您想兩全其美,這是一個“ writableComputedArray”。 如果您從數組中添加/刪除,並且隨后對observable的重新計算執行相同的添加/刪除,則訂閱服務器將不會第二次收到通知。 但是,您有責任確保數組的計算與實際添加/刪除的內容之間沒有差異。 您可以通過在可排序綁定的afterMove事件中進行必要的更改來完成此操作。
ko.writeableComputedArray = function (evaluatorFunction) {
// We use this to get notified when the evaluator function recalculates the array.
var computed = ko.computed(evaluatorFunction);
// This is what gets returned to the caller and they can subscribe to
var observableArray = ko.observableArray(computed());
// When the computed changes, make the same changes to the observable array.
computed.subscribe(function (newArray) {
// Add any new values
newArray.forEach(function (value) {
var i = observableArray.indexOf(value);
if (i == -1) {
// It's a new value, push it
observableArray.unshift(value);
}
});
// Remove any old ones. Loop backwards since we're removing items from it.
for (var valueIndex = observableArray().length - 1; valueIndex >= 0; valueIndex--) {
var value = observableArray()[valueIndex];
var i = newArray.indexOf(value);
if (i == -1) {
// It's an old value, remove it
observableArray.remove(value);
}
}
});
return observableArray;
};
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