Create an object out of dot notation

Question

This is a reverse question to this question.

Given an object x={a:1,b:2} and a string c.d=3, modify object x to the following:

Answer 1

What about this :

function setObj (str, value, obj) {
    var ref = obj, keys = str.split('.');
    while (keys.length) {
        var currentKey = keys.shift();
        ref[currentKey] = keys.length ? (ref[currentKey]  ? ref[currentKey] : {}) : value;
        ref = ref[currentKey];
    }
}

Example with an input object using (could be some form values extracted with $.serializeArray)

var serializedInputs = [
    {name: 'fruits[1][name]', value: 'Banana'},
    {name: 'fruits[1][id]', value: '1'},
    {name: 'fruits[2][name]', value: 'Strawberry'},
    {name: 'fruits[2][id]', value: '2'},
    {name: 'fruits[3][name]', value: 'Raspberry'},
    {name: 'fruits[3][id]', value: '3'},
    {name: 'fruits[4][name]', value: 'Kiwi'},
    {name: 'fruits[4][id]', value: '4'},
    {name: 'fruits[5][name]', value: 'Mango'},
    {name: 'fruits[5][id]', value: '5'},
    {name: 'selected_fruit_id', value: '1'},
]
// This variable holds the result
var obj = {}
serializedInputs.forEach(function(item) {
    // Turning square brackets into dot notation
    setObj(item.name.replace(/\]/g, '').replace(/\[/g, '.'), item.value, obj);
})

Result

{
    "fruits": {
        "1": {
            "name": "Banana",
            "id": "1"
        },
        "2": {
            "name": "Strawberry",
            "id": "2"
        },
        "3": {
            "name": "Raspberry",
            "id": "3"
        },
        "4": {
            "name": "Kiwi",
            "id": "4"
        },
        "5": {
            "name": "Mango",
            "id": "5"
        }
    },
    "selected_fruit_id": "1"
}

Answer 2

How about this?

It'll create or copy/overwrite an existing object.

function expando(obj, base) {
    return Object.keys(obj)
      .reduce((clone, key) => {
        key.split('.').reduce((innerObj, innerKey, i, arr) => 
          innerObj[innerKey] = (i+1 === arr.length) ? obj[key] : innerObj[innerKey] || {}, clone)
        return clone;
    }, Object.assign({}, base));
}

console.log(expando({'a.b': 1})) // { a: { b : 1 }}
console.log(expando({'b.c': 2}, { a: 1 })) // { a: 1, b: { c: 2 }}
console.log(expando({'b.c.d': 2, 'e.f': 3}, { a: 1 })) // { a: 1, b: { c: { d: 2 } }, e: { f: 3}}

NOTE: ES6 needed for arrow functions and Object.assign().

Feel free to play around:

https://jsbin.com/setazahuce/1/edit?js,console

Answer 3

I believe dojo's setObject does what you want. If you (understandably) don't want to pull in all of dojo then I would recommend examining their (freely available) source or loading just base (only 4k) via AMD. It looks something like this :

function setObject(name, value, context) {
    var parts=name.split("."), 
    p=parts.pop();
    for(var i=0, j; context && (j=parts[i]); i++){
        context = (j in context ? context[j] : context[j]={});
    }
    return context && p ? (context[p]=value) : undefined; // Object
}

So in your case you would do :

x={a:1,b:2};
setObject("c.d", 3, x);

Warning : unless you only ever deal with trivial cases, I would urge you to still go check out the full dojo implementation, which deals with cases where no context is provided etc.

Answer 4

Off the top of my head I guess you can do something like this:

function addValueToObj(obj, newProp) {
    newProp = newProp.split("=");       // separate the "path" from the "value"

    var path = newProp[0].split("."),     // separate each step in the "path"
        val = newProp.slice(1).join("="); // allow for "=" in "value"

    for (var i = 0, tmp = obj; i < path.length - 1; i++) {
       tmp = tmp[path[i]] = {};     // loop through each part of the path adding to obj
    }
    tmp[path[i]] = val;             // at the end of the chain add the value in
}

var x = {a:1, b:2};
addValueToObj(x, "c.d=3");
// x is now {"a":1,"b":2,"c":{"d":"3"}}
addValueToObj(x, "e.f.g.h=9=9");
// x is now {"a":1,"b":2,"c":{"d":"3"},"e":{"f":{"g":{"h":"9=9"}}}}

Demo: http://jsfiddle.net/E8dMF/1/

Answer 5

You can do this with lodash.set()

> l=require('lodash')
> x={a:1,b:2};
{ a: 1, b: 2 }
> l.set(x, 'c.d', 3)
{ a: 1, b: 2, c: { d: 3 } }

Answer 6

Here's a heavily commented version that should be somewhat straightforward to understand.

// stores the configured data
configStore = {};

config = {
  set: function(keyValueString) {

    // Split the string by the =
    var pair = keyValueString.split('=');

    // left of the = is the key path
    var keyPath = pair[0];

    // right of the = is the value to set
    var value = pair[1];

    // split keyPath into an array of keys
    var keys = keyPath.split('.');
    var key; // used in loop

    // the current level of object we are drilling into.
    // Starts as the main root config object.
    var currentObj = configStore;

    // Loop through all keys in the key path, except the last one (note the -1).
    // This creates the object structure implied by the key path.
    // We want to do something different on the last iteration.
    for (var i=0; i < keys.length-1; i++) {

      // Get the current key we are looping
      key = keys[i];

      // If the requested level on the current object doesn't exist,
      // make a blank object.
      if (typeof currentObj[key] === 'undefined') {
        currentObj[key] = {};
      }

      // Set the current object to the next level of the keypath,
      // allowing us to drill in.
      currentObj = currentObj[key];
    }

    // Our loop doesn't handle the last key, because that's when we
    // want to set the actual value. So find the last key in the path.
    var lastKey = keys[keys.length-1]

    // Set the property of the deepest object to the value.
    currentObj[lastKey] = value;
  }
};

// Do it.
config.set('omg.wtf.bbq=123')

// Check it.
alert(configStore.omg.wtf.bbq); // 123