前言

相信大家都知道在通常情况下，在Node.js中我们可以通过underscore的extend或者lodash的merge来合并两个对象，但是对于像下面这种复杂的对象，要如何来应对呢？下面来一起学习学习吧。

Node.js合并两个复杂对象

例如我有以下两个object：

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
 }
 ]
};

希望合并之后的结果输出成下面这样：

{ 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 }

通过underscore或者lodash现有的方法我们无法实现上述结果，那只能自己写代码来实现了。

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;}

将上述代码稍作改进，我们可以实现在合并过程中将Number类型的值自动相加。

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('_key') > -1){
 def[i] = obj[i];
 }
 else{
 def[i] += obj[i];
 }
 }
 }
 return def;
}

例如有以下两个对象：

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
};

合并之后的结果如下：

{
 "_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
}