在Knockout中设置Observable的值不更新 [英] Setting value of Observable not updating in Knockout

问题描述

（每天都有很多问题链接回原因为什么我不能设置我的观察值，而不是有这么多不同的答案说同样的事情我想创建一个问题来引用回来每个人）

(There are a ton of questions every day that link back to why can't I set the value of my observable, instead of having so many different answers saying the same thing I wanted to create a question to refer back to for everyone)

设置我的observable的值observableArray没有更新！

Setting the value of my observable observableArray isn't updating!

为什么我不能添加item进入我的Knockout可观察数组？

Why can't I add an item into my Knockout observable array?

推荐答案

Knockout Observable / Observable Array的设置值不会更新

您需要使用setter函数来更新observable / observableArray的值 -

Setting value of Knockout Observable / Observable Array doesn't update

You need to use the setter function to update the value of your observable / observableArray -

Ex。 1（可观察） -

Ex. 1 (observable) -

var name = 'John';
var myValue = ko.observable();
myValue(name); // Set myValue equal to John, update any subscribers

var newObservable = ko.observable('Bill');
myValue(newObservable()); // Set myValue equal to the value of newObservable, which is Bill

Ex。 2（observableArray） -

Ex. 2 (observableArray) -

var names = ['John', 'William', 'Dave'];
var myArray = ko.observableArray();
myArray(names); // Set myArray equal to the array of names John, update any subscribers

var newArray = ko.observableArray(['Sanford']);
myArray(newArray()); // Makes a clone of the array

注意请参阅此问题以了解为什么这可能不是你想要做的 - 在knockoutJS中克隆/复制observablearray的最佳方法是什么？

Note See this Question to understand why this probably not what you are trying to do - What is the best way of cloning/copying an observablearray in knockoutJS?

您需要将项目推入observableArray，不 observableArray的基础值 -

You need to push the item into the observableArray, not the underlying value of the observableArray -

var name = 'John';
var myValue = ko.observable(name);
var myArray = ko.observableArray();
myValue.push(myValue()); // Add myValue to my observableArray**

在视图模型中创建要使用/共享的模型

您可以创建一个可在您的视图模型中使用的可重用模型。这类似于在C＃中使用类来创建具有公共属性的对象。

Creating a model to use/share in your view model

You can create a re-usable model to use in your view models. This is similar to using a class in C# to create objects that have common properties.

function objectModel(item) {
    var self = this;
    self.Name = ko.observable(item.name);
    self.Description = ko.observable(item.description);
}

可以像 -

var object = {
    name: 'John',
    description: 'a person'
}

var john = new objectModel(object);

这也可以通过参数而不仅仅是对象来完成 -

Which could also be done by parameters instead of just objects -

function objectModel(name, description) {
    var self = this;
    self.Name = ko.observable(name);
    self.Description = ko.observable(description);
}

var john = new objectModel('John', 'a person');

这篇关于在Knockout中设置Observable的值不更新的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！