JSON.stringify() - how to know current depth in replacer

Question

I have recursivity problem when trying to stringify an object.

I wonder if anyone have a tip to know what is the current depth when iterating trough key -> value in the replacer ? I want to replace a reference by its ID, but only when I'm at a specific depth.

Here is a minimalist object to give an exemple :

var a = {
  id: 'idOfA',
  linkedItems: []
};

var b = {
  id: 'idOfB',
  linkedItems: []
};

var c = {
  id: 'idOfC',
  linkedItems: []
};

a.linkedItems.push({
  from: 0,
  to: 0,
  item: b
});
b.linkedItems.push({
  from: 0,
  to: 0,
  item: a
}, {
  from: 0,
  to: 0,
  item: c
});
c.linkedItems.push({
  from: 0,
  to: 0,
  item: a
}, {
  from: 0,
  to: 0,
  item: b
});

var obj = {
  things: {},
  otherThings: {},
  items: [a, b, c]
};

From obj, I need to replace each references in the "linkedItems" attribute, by their id. I tough the easier way was to stringify it first ... :)

The "replacer" is really just a filtering mechanism, it doesn't keep count of the depth in the object being stringified. — adeneo, Jul 29 '16 at 19:40
Sorry, congratulations on being one of the few people in the world to take advantage of the replacer, which is a grossly under-utilized feature, but it won't help you here. — , Jul 29 '16 at 20:03
@RomanPerekhrest The input data is irrelevant to the question. — , Jul 29 '16 at 20:04
@AbdennourTOUMI There is no point in asking for an attempt. Either the replacer can access the current depth, or it can't. In this particular case, it can't. — , Jul 29 '16 at 20:04
Yes, sorry. I meant that :). I wrote it quickly to give an idea. Let me correct it :) — Alann S., Jul 29 '16 at 20:25
Here it is, I made a fully rewrited exemple, which can be compiled :p. — Alann S., Jul 29 '16 at 20:36

score 0 · Answer 1 · answered Jul 29 '16 at 20:41

I will assume what you call "references" (a ,b & c) are String .

var a="SA", b="SB", c="SC" ;

var obj = {
  things: {},
  otherThings: {},
  items: {
    a: {
      _id: 'idOfA',
      linkedItems: [b, c]
    },
    b: {
      _id: 'idOfB',
      linkedItems: [a]
    },
    c: {
      _id: 'idOfC',
      linkedItems: [a, b]
    }
  }
}
function getID(attr){
   var mapping={'SA':'a','SB':'b','SC':'c'};
   return obj.items[mapping[attr]]._id;
   

};

Object.keys(obj.items).map((value, index) =>{
  obj.items[value].linkedItems = obj.items[value].linkedItems.map((e)=>getID(e));
});

console.log(obj)

Sorry, but I don't see any possible way to adapt this to my needs :s. You can check my first post for more details :) — Alann S., Jul 29 '16 at 21:37

score 0 · Accepted Answer · answered Jul 29 '16 at 22:55

I finally found a way. But I'm not sure it's the optimal way to do it :s.

here is what I added :

Object.defineProperty(Object.prototype, 'map', {
    value: function (f, ctx) {
        ctx = ctx || this;
        var self = this;
        var result = {};
        Object.keys(self).forEach(function (k) {
            result[k] = f.call(ctx, self[k], k, self);
        });

        return result;
    }
});

var okayItems = obj.items.map(function (item, index) {
    item = Object.assign({}, item, {
        linkedItems: item.linkedItems.map(function (linkedItem) {
            linkedItem = linkedItem.map(function (value, key) {
                return (key === 'item') ? value.id : value;
            });

            return linkedItem;
        })
    });

    return item;
});

score -1 · Answer 3 · edited May 23 '17 at 11:51

-1

You can implement the toJson function into the object of yours, and handle this case within it, then when you call JSON.stringify it will be returned from that object.

Difference between toJSON() and JSON.Stringify()

edited May 23 '17 at 11:51

Community

1
1

answered Jul 29 '16 at 19:36

MoustafaS

1,991
11
20

I already tried this :). The problem is that it will always return the id even on items which aren't deep enough in my object. – Alann S. Jul 29 '16 at 19:56

JSON.stringify() - how to know current depth in replacer

3 Answers3