字符串化(转换为 JSON)具有循环引用的 JavaScript 对象
我有一个包含循环引用的 JavaScript 对象定义:它有一个引用父对象的属性.
I've got a JavaScript object definition which contains a circular reference: it has a property that references the parent object.
它还有一些我不想传递给服务器的功能.我将如何序列化和反序列化这些对象?
It also has functions that I don't want to be passed through to the server. How would I serialize and deserialize these objects?
我读到最好的方法是使用 Douglas Crockford 的 stringify.但是,我在 Chrome 中收到以下错误:
I've read that the best method to do this is to use Douglas Crockford's stringify. However, I'm getting the following error in Chrome:
TypeError:将循环结构转换为 JSON
TypeError: Converting circular structure to JSON
代码:
function finger(xid, xparent){
this.id = xid;
this.xparent;
//other attributes
}
function arm(xid, xparent){
this.id = xid;
this.parent = xparent;
this.fingers = [];
//other attributes
this.moveArm = function() {
//moveArm function details - not included in this testcase
alert("moveArm Executed");
}
}
function person(xid, xparent, xname){
this.id = xid;
this.parent = xparent;
this.name = xname
this.arms = []
this.createArms = function () {
this.arms[this.arms.length] = new arm(this.id, this);
}
}
function group(xid, xparent){
this.id = xid;
this.parent = xparent;
this.people = [];
that = this;
this.createPerson = function () {
this.people[this.people.length] = new person(this.people.length, this, "someName");
//other commands
}
this.saveGroup = function () {
alert(JSON.stringify(that.people));
}
}
这是我为这个问题创建的测试用例.这段代码中有错误,但本质上我在对象中有对象,并且传递给每个对象的引用以显示创建对象时父对象是什么.每个对象还包含我不希望字符串化的函数.我只想要 Person.Name
等属性.
This is a test case that I created for this question. There are errors within this code but essentially I have objects within objects, and a reference passed to each object to show what the parent object is when the object is created. Each object also contains functions, which I don't want stringified. I just want the properties such as the Person.Name
.
我如何在发送到服务器之前进行序列化,并在假设传回相同的 JSON 的情况下对其进行反序列化?
How do I serialize before sending to the server and deserialize it assuming that the same JSON is passed back?
推荐答案
循环结构当你有一个对象的属性直接是对象本身时会发生错误(a ->a
)或间接(a -> b -> a
).
Circular structure error occurs when you have a property of the object which is the object itself directly (a -> a
) or indirectly (a -> b -> a
).
为了避免错误消息,告诉 JSON.stringify 在遇到循环引用时该怎么做.例如,如果您有一个人指向另一个人(父母"),而该人可能(也可能不)指向原始人,请执行以下操作:
To avoid the error message, tell JSON.stringify what to do when it encounters a circular reference. For example, if you have a person pointing to another person ("parent"), which may (or may not) point to the original person, do the following:
JSON.stringify( that.person, function( key, value) {
if( key == 'parent') { return value.id;}
else {return value;}
})
stringify
的第二个参数是一个过滤函数.在这里,它只是将引用的对象转换为其 ID,但您可以自由地做任何您想做的事情来破坏循环引用.
The second parameter to stringify
is a filter function. Here it simply converts the referred object to its ID, but you are free to do whatever you like to break the circular reference.
您可以使用以下代码测试上述代码:
You can test the above code with the following:
function Person( params) {
this.id = params['id'];
this.name = params['name'];
this.father = null;
this.fingers = [];
// etc.
}
var me = new Person({ id: 1, name: 'Luke'});
var him = new Person( { id:2, name: 'Darth Vader'});
me.father = him;
JSON.stringify(me); // so far so good
him.father = me; // time travel assumed :-)
JSON.stringify(me); // "TypeError: Converting circular structure to JSON"
// But this should do the job:
JSON.stringify(me, function( key, value) {
if(key == 'father') {
return value.id;
} else {
return value;
};
});
顺便说一句,我会为parent
"选择一个不同的属性名称,因为它是许多语言(和 DOM)中的保留字.这往往会导致混乱......
BTW, I'd choose a different attribute name to "parent
" since it is a reserved word in many languages (and in DOM). This tends to cause confusion down the road...
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