Question

我知道有很多＆＃34;在JS＆＃34;中合并两个对象数组。问题，我已经阅读了大部分内容。与我试图做的最相似的是：

我的问题不同，因为我试图进行完整的SQL连接，其中数组的大小不同，并且会有新列。

例如：

JSON1 = [{Color:"Blue", ID:"15", Size:"Large",Shape:"Square"},
         {Color:"Red", ID:"9", Size:"Medium",Shape:"Circle"},
         {Color:"Red", ID:"2", Size:"Large",Shape:"Triangle"},
         {Color:"Yellow", ID:"3", Size:"Small",Shape:"Square"}];

JSON2 = [{Color:"Blue", Name:"Henry", Inches:"51"},
         {Color:"Red", Name:"Jane", Inches:"7"},
         {Color:"Pink", Name:"Jack", Inches:"14"}];

期望的输出：

OUTPUT =[{Color:"Blue", ID:"15", Size:"Large",Shape:"Square",Name:"Henry", Inches:"51"},
         {Color:"Red", ID:"9", Size:"Medium",Shape:"Circle",Name:"Jane", Inches:"7"},
         {Color:"Red", ID:"2", Size:"Large",Shape:"Triangle",Name:"Jane", Inches:"7"},
         {Color:"Yellow", ID:"3", Size:"Small",Shape:"Square",Name:null, Inches:null},
         {Color:"Pink", ID:null, Size:null,Shape:null,Name:"Jack", Inches:"14"}];

因此，类似于完整的SQL连接，我希望输出JSON包含所有列，匹配时匹配，但如果第二个JSON中的键：值对不匹配，则为新行第一个中任何一个对象中的那些。

到目前为止我的内容如下。它通常有效，但有几个问题。我正在合并一个特定的预定义值，并且函数可以找出匹配值的位置。此外，如果我向JSON2添加多个新属性列，我的函数将失败（即，如果JSON2具有Color和Inches，但不是Color，Inches和Name，则它可以工作。）因为我只是将一个属性散列到另一个属性

var hash={};
for(var e in JSON2){
    hash[JSON2[e]["Color"]]= JSON2[e]["Inches"];
}
var trackHash = hash;
for(var k in JSON1){
    JSON1[k]["Inches"] = hash[JSON1[k]["Color"]];
    if(hash[JSON1[k]["Color"]]===undefined){
        delete trackHash[JSON1[k]["Color"]];
    }
}
for(var obj in JSON2){
    if(trackHash[JSON2[obj]["Color"]]!==undefined){
        JSON1.push(JSON2[obj]);
    }
}

Answer 1

我认为这可能是你的事后，...

它可以被优化等，但希望这是一个开始。

哦，为了简单起见，我也使用了Object.assign，因此请注意旧版浏览器，您可能需要使用polyfill，或者使用像lodash这样的东西。

var JSON1 = [{Color:"Blue", ID:"15", Size:"Large",Shape:"Square"},
         {Color:"Red", ID:"9", Size:"Medium",Shape:"Circle"},
         {Color:"Red", ID:"2", Size:"Large",Shape:"Triangle"},
         {Color:"Yellow", ID:"3", Size:"Small",Shape:"Square"}];

var JSON2 = [{Color:"Blue", Name:"Henry", Inches:"51"},
         {Color:"Red", Name:"Jane", Inches:"7"},
         {Color:"Pink", Name:"Jack", Inches:"14"}];

function fullJoin(a, b) {
  var r = [];
  a.forEach(function (a) {
    var found = false;
    b.forEach(function (b) {
      if (a.Color === b.Color) {
        var j = Object.assign(a, b);
        r.push(j);
        found = true;
      }
    })
    if (!found) r.push(a);
  });
  b.forEach(function (b) {
    var found = false;
    a.forEach(function (a) {
       if (a.Color === b.Color) found = true;
    });
    if (!found) r.push(b);
  });
  return r;
}

var a = fullJoin(JSON1, JSON2);
a.forEach(function (a) { console.log(JSON.stringify(a)); });

Answer 2

所以这就是我对数组做的事情：

使用Array.prototype.map通过复制JSON1
<中相应类似键的键/值来从JSON2创建新数组/ LI>
还跟踪了JSON2中不在JSON1的密钥，并将其添加到其后的结果中。

＆＃13;

var JSON1 = [{Color:"Blue", ID:"15", Size:"Large",Shape:"Square"},
         {Color:"Red", ID:"9", Size:"Medium",Shape:"Circle"},
         {Color:"Red", ID:"2", Size:"Large",Shape:"Triangle"},
         {Color:"Yellow", ID:"3", Size:"Small",Shape:"Square"}];

var JSON2 = [{Color:"Blue", Name:"Henry", Inches:"51"},
         {Color:"Red", Name:"Jane", Inches:"7"},
         {Color:"Pink", Name:"Jack", Inches:"14"}];


var excluded = {};

// Join JSON2 to JSON1
// also track elements in JSON2 not in JSON1
var result = JSON1.map(function(a) {
      JSON2.forEach(function(element, index, array) {
        if (a.Color === element.Color) {
          Object.keys(element).forEach(function(key) {
            a[key] = element[key];
          });
        } else {
            this.visited = this.visited + 1 || 0; 
            if(this.visited == array.length)  {
              this.found = this.found || [];
              this.found.push(element);
            }
        }
      }, this);
      this.visited = 0;
        return a;
      }, excluded);

// add elements in JSON2 not in JSON1
if(excluded.found) {
   excluded.found.forEach(function(element) {
       result.push(element);
   });
}

console.log(result);

＆＃13;

.as-console-wrapper{top:0;max-height:100%!important;}

＆＃13;

如果这对您有用，请告诉我您的反馈。谢谢！

与Javascript对象数组的SQL完全连接的等价物

2 个答案: