javascript - How to restore circular references (e.g. "$id") from Json.NET-serialized JSON?

Question

Is there an existing javascript library which will deserialize Json.Net with reference loop handling?

{
    "$id": "1",
    "AppViewColumns": [
        {
            "$id": "2",
            "AppView": {"$ref":"1"},
            "ColumnID": 1,
        }
    ]
}

this should deserialize to an object with a reference loop between the object in the array and the outer object

Answer 1

The answers given almost worked for me, but the latest version of MVC, JSON.Net, and DNX uses "$ref" and "$id", and they may be out of order. So I've modified user2864740's answer.

I should note that this code does not handle array references, which are also possible.

function RestoreJsonNetReferences(g) {
var ids = {};

function getIds(s) {
// we care naught about primitives
if (s === null || typeof s !== "object") { return s; }

var id = s['$id'];
if (typeof id != "undefined") {
delete s['$id'];

// either return previously known object, or
// remember this object linking for later
if (ids[id]) {
throw "Duplicate ID " + id + "found.";
}
ids[id] = s;
}

// then, recursively for each key/index, relink the sub-graph
if (s.hasOwnProperty('length')) {
// array or array-like; a different guard may be more appropriate
for (var i = 0; i < s.length; i++) {
getIds(s[i]);
}
} else {
// other objects
for (var p in s) {
if (s.hasOwnProperty(p)) {
getIds(s[p]);
}
}
}
}

function relink(s) {
// we care naught about primitives
if (s === null || typeof s !== "object") { return s; }

var id = s['$ref'];
delete s['$ref'];

// either return previously known object, or
// remember this object linking for later
if (typeof id != "undefined") {
return ids[id];
}

// then, recursively for each key/index, relink the sub-graph
if (s.hasOwnProperty('length')) {
// array or array-like; a different guard may be more appropriate
for (var i = 0; i < s.length; i++) {
s[i] = relink(s[i]);
}
} else {
// other objects
for (var p in s) {
if (s.hasOwnProperty(p)) {
s[p] = relink(s[p]);
}
}
}

return s;
}

getIds(g);
return relink(g);
}