javascript - 解决来自 JSON 对象的循环引用

Question

如果我有一个来自 json.net 的序列化 JSON，如下所示:

User:{id:1,{Foo{id:1,prop:1}},
FooList{$ref: "1",Foo{id:2,prop:13}}

我想在 FooList 上有一个 foreach 的 knockout 输出，但我不确定如何继续，因为 $ref 东西可能会抛出东西。

我认为解决方案是以某种方式强制所有 Foos 在 FooList 中呈现，而不是使用:

PreserveReferencesHandling = PreserveReferencesHandling.Objects

但这似乎很浪费..

Answer 1

我发现了一些错误并实现了数组支持:

function resolveReferences(json) {
    if (typeof json === 'string')
        json = JSON.parse(json);

    var byid = {}, // all objects by id
        refs = []; // references to objects that could not be resolved
    json = (function recurse(obj, prop, parent) {
        if (typeof obj !== 'object' || !obj) // a primitive value
            return obj;
        if (Object.prototype.toString.call(obj) === '[object Array]') {
            for (var i = 0; i < obj.length; i++)
                // check also if the array element is not a primitive value
                if (typeof obj[i] !== 'object' || !obj[i]) // a primitive value
                    continue;
                else if ("$ref" in obj[i])
                    obj[i] = recurse(obj[i], i, obj);
                else
                    obj[i] = recurse(obj[i], prop, obj);
            return obj;
        }
        if ("$ref" in obj) { // a reference
            var ref = obj.$ref;
            if (ref in byid)
                return byid[ref];
            // else we have to make it lazy:
            refs.push([parent, prop, ref]);
            return;
        } else if ("$id" in obj) {
            var id = obj.$id;
            delete obj.$id;
            if ("$values" in obj) // an array
                obj = obj.$values.map(recurse);
            else // a plain object
                for (var prop in obj)
                    obj[prop] = recurse(obj[prop], prop, obj);
            byid[id] = obj;
        }
        return obj;
    })(json); // run it!

    for (var i = 0; i < refs.length; i++) { // resolve previously unknown references
        var ref = refs[i];
        ref[0][ref[1]] = byid[ref[2]];
        // Notice that this throws if you put in a reference at top-level
    }
    return json;
}