An introduction to how to merge two complex objects in Node.js

The following article mainly introduces how to merge two complex objects in Node.js. The article provides detailed sample code. I believe it has certain reference value for everyone's understanding and learning. Friends in need can refer to it, let’s take a look below.

Preface

I believe everyone knows that under normal circumstances, in Node.js we can use underscore’s extend or lodash’s merge. Merge two objects, but how to deal with complex objects like the following? Let’s learn together below.

Node.js merges two complex objects

For example, I have the following two objects:

var obj1 = {
 "name" : "myname",
 "status" : 0,
 "profile": { "sex":"m", "isactive" : true},
 "strarr":["one", "three"],
 "objarray": [
 {
  "id": 1,
  "email": "a1@me.com",
  "isactive":true
 },
 {
  "id": 2,
  "email": "a2@me.com",
  "isactive":false
 }
 ]
};

var obj2 = {
 "name" : "myname",
 "status" : 1,
 "newfield": 1,
 "profile": { "isactive" : false, "city": "new York"},
 "strarr":["two"],
 "objarray": [
 {
  "id": 1,
  "isactive":false
 },
 {
  "id": 2,
  "email": "a2modified@me.com"
 },
 {
  "id": 3,
  "email": "a3new@me.com",
  "isactive" : true
 }
 ]
};

I hope that the merged result will be output as follows:

{ name: 'myname',
 status: 1,
 profile: { sex: 'm', isactive: false, city: 'new York' },
 strarr: [ 'one', 'three', 'two' ],
 objarray: 
 [ { id: 1, email: 'a1@me.com', isactive: false },
 { id: 2, email: 'a2modified@me.com', isactive: false },
 { id: 3, email: 'a3new@me.com', isactive: true } ],
newfield: 1 }

We cannot achieve the above through the existing methods of underscore or lodash. As a result, you can only write code yourself to achieve it.

function mergeObjs(def, obj) {
 if (!obj) {
 return def;
 } else if (!def) {
 return obj;
 }

 for (var i in obj) {
 // if its an object
 if (obj[i] != null && obj[i].constructor == Object)
 {
  def[i] = mergeObjs(def[i], obj[i]);
 }
 // if its an array, simple values need to be joined. Object values need to be remerged.
 else if(obj[i] != null && (obj[i] instanceof Array) && obj[i].length > 0)
 {
  // test to see if the first element is an object or not so we know the type of array we're dealing with.
  if(obj[i][0].constructor == Object)
  {
  var newobjs = [];
  // create an index of all the existing object IDs for quick access. There is no way to know how many items will be in the arrays.
  var objids = {}
  for(var x= 0, l= def[i].length ; x < l; x++ )
  {
   objids[def[i][x].id] = x;
  }

  // now walk through the objects in the new array
  // if the ID exists, then merge the objects.
  // if the ID does not exist, push to the end of the def array
  for(var x= 0, l= obj[i].length; x < l; x++)
  {
   var newobj = obj[i][x];
   if(objids[newobj.id] !== undefined)
   {
   def[i][x] = mergeObjs(def[i][x],newobj);
   }
   else {
   newobjs.push(newobj);
   }
  }

  for(var x= 0, l = newobjs.length; x<l; x++) {
   def[i].push(newobjs[x]);
  }
  }
  else {
  for(var x=0; x < obj[i].length; x++)
  {
   var idxObj = obj[i][x];
   if(def[i].indexOf(idxObj) === -1) {
    def[i].push(idxObj);
   }
  }
  }
 }
 else
 {
  def[i] = obj[i];
 }
 }
 return def;}

By slightly improving the above code, we can automatically add Number type values ​​during the merging process.

function merge(def, obj) {
 if (!obj) {
  return def;
 }
 else if (!def) {
  return obj;
 }

 for (var i in obj) {
  // if its an object
  if (obj[i] != null && obj[i].constructor == Object)
  {
   def[i] = merge(def[i], obj[i]);
  }
  // if its an array, simple values need to be joined. Object values need to be re-merged.
  else if(obj[i] != null && (obj[i] instanceof Array) && obj[i].length > 0)
  {
   // test to see if the first element is an object or not so we know the type of array we're dealing with.
   if(obj[i][0].constructor == Object)
   {
    var newobjs = [];
    // create an index of all the existing object IDs for quick access. There is no way to know how many items will be in the arrays.
    var objids = {}
    for(var x= 0, l= def[i].length ; x < l; x++ )
    {
     objids[def[i][x].id] = x;
    }

    // now walk through the objects in the new array
    // if the ID exists, then merge the objects.
    // if the ID does not exist, push to the end of the def array
    for(var x= 0, l= obj[i].length; x < l; x++)
    {
     var newobj = obj[i][x];
     if(objids[newobj.id] !== undefined)
     {
      def[i][x] = merge(def[i][x],newobj);
     }
     else {
      newobjs.push(newobj);
     }
    }

    for(var x= 0, l = newobjs.length; x<l; x++) {
     def[i].push(newobjs[x]);
    }
   }
   else {
    for(var x=0; x < obj[i].length; x++)
    {
     var idxObj = obj[i][x];
     if(def[i].indexOf(idxObj) === -1) {
      def[i].push(idxObj);
     }
    }
   }
  }
  else
  {
   if (isNaN(obj[i]) || i.indexOf(&#39;_key&#39;) > -1){
    def[i] = obj[i];
   }
   else{
    def[i] += obj[i];
   }
  }
 }
 return def;
}

For example, there are the following two objects:

var data1 = {
 "_id" : "577327c544bd90be508b46cc",
 "channelId_info" : [
 {
  "channelId_key" : "0",
  "secondLevel_group" : [
  {
   "secondLevel_key" : "568cc36c44bd90625a045c60",
   "sender_group" : [
   {
    "sender_key" : "577327c544bd90be508b46cd",
    "sender_sum" : 40.0
   }
   ],
   "senders_sum" : 40.0
  }
  ],
  "channelId_sum" : 40.0
 }
 ],
 "car_sum" : 40.0
};

var data2 = {
 "_id" : "577327c544bd90be508b46cc",
 "channelId_info" : [
 {
  "channelId_key" : "0",
  "secondLevel_group" : [
  {
   "secondLevel_key" : "568cc36c44bd90625a045c60",
   "sender_group" : [
   {
    "sender_key" : "577327c544bd90be508b46cd",
    "sender_sum" : 20.0
   },
   {
    "sender_key" : "5710bcc7e66620fd4bc0914f",
    "sender_sum" : 5.0
   }
   ],
   "senders_sum" : 25.0
  },
  {
   "secondLevel_key" : "55fbeb4744bd9090708b4567",
   "sender_group" : [
   {
    "sender_key" : "5670f993a2f5dbf12e73b763",
    "sender_sum" : 10.0
   }
   ],
   "senders_sum" : 10.0
  }
  ],
  "channelId_sum" : 35.0
 },
 {
  "channelId_key" : "1",
  "secondLevel_group" : [
  {
   "secondLevel_key" : "568cc36c44bd90625a045c60",
   "sender_group" : [
   {
    "sender_key" : "577327c544bd90be508b46cd",
    "sender_sum" : 20.0
   }
   ],
   "senders_sum" : 20.0
  }
  ],
  "channelId_sum" : 20.0
 }
 ],
 "car_sum" : 55.0
};

The result after merging is as follows ：

{
 "_id": "577327c544bd90be508b46cc",
 "channelId_info": [
  {
   "channelId_key": "0",
   "secondLevel_group": [
    {
     "secondLevel_key": "568cc36c44bd90625a045c60",
     "sender_group": [
      {
       "sender_key": "577327c544bd90be508b46cd",
       "sender_sum": 60
      },
      {
       "sender_key": "5710bcc7e66620fd4bc0914f",
       "sender_sum": 5
      }
     ],
     "senders_sum": 65
    },
    {
     "secondLevel_key": "55fbeb4744bd9090708b4567",
     "sender_group": [
      {
       "sender_key": "5670f993a2f5dbf12e73b763",
       "sender_sum": 10
      }
     ],
     "senders_sum": 10
    }
   ],
   "channelId_sum": 75
  },
  {
   "channelId_key": "1",
   "secondLevel_group": [
    {
     "secondLevel_key": "568cc36c44bd90625a045c60",
     "sender_group": [
      {
       "sender_key": "577327c544bd90be508b46cd",
       "sender_sum": 20
      }
     ],
     "senders_sum": 20
    }
   ],
   "channelId_sum": 20
  }
 ],
 "car_sum": 95
}

The above is the entire content of this article. I hope it will be helpful to everyone’s study. For more related content, please pay attention to the PHP Chinese website!

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