Knockout.js-在视图模型中使用循环引用进行调试 [英] knockoutjs - debug with circular reference in view model

问题描述

根据设计，视图模型具有循环引用，利用<pre data-bind="text: ko.toJSON($data)"></pre>进行调试以抛出:

The view model has a circular reference, by design, making the use of <pre data-bind="text: ko.toJSON($data)"></pre> for debugging to throw:

Unable to parse bindings.
Message: TypeError: Converting circular structure to JSON;
Bindings value: text: ko.toJSON($data) 

有没有办法解决这个问题?

Is there a way to work around this?

推荐答案

最终导致您出错的是ko.toJSON内部对JSON.stringify的调用.

It is ultimately the call to JSON.stringify inside of ko.toJSON that causes your error.

一种控制JSON输出的方法是通过在对象上提供toJSON函数，如下所述:

One way that you can control the output of your JSON is by supplying a toJSON function on your object as described here: http://www.knockmeout.net/2011/04/controlling-how-object-is-converted-to.html. That way you can remove the circular reference in the appropriate place.

您还可以使用其他一些技术.

There are a few other techniques that you could use for this as well.

• 您可以将第二个参数传递给ko.toJSON.这是JSON.stringify的replacer选项，如下所述:

• You can pass a second argument to ko.toJSON. This is the replacer option to JSON.stringify as described here:

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/JSON /stringify .

例如，您可以传递一组属性以包括:

For example, you can pass an array of properties to include like:

ko.toJSON(myobject, ["one", "two", "three"])

您可以将您不想将其变成JSON的属性附加为"sub" -observable，例如:

You can attach a property that you don't want to get turned into JSON as a "sub"-observable like:

this.data = ko.observable();
this.data.parent = parent;

在这种情况下，data会变成JSON，但是parent会消失，因为它是可观察对象的一个​​属性，已经解开了它的值.

In this case, data will get turned into JSON, but parent will just disappear, as it is a property on an observable that already gets unwrapped into its value.

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