从两个不同的对象数组中选择数据以创建一个新的对象数组

Question

我有以下对象数组：const formulas =[    { "formulaID": "1", "versionID": 1, "formulaClass": 3, "formulaType": "34", "outputName": "Chocolate Milk 2%" },    { "formulaID": "4", "versionID": 1, "formulaClass": 3, "formulaType": "17", "outputName": "Hazelnut Creamer" },    { "formulaID": "6", "versionID": 1, "formulaClass": 3, "formulaType": "23", "outputName": "White Milk 2%" }];const yields =[    { "formulaID": "4", "versionID": 1, "yieldFactor": 0.93 },    { "formulaID": "4", "versionID": 2, "yieldFactor": 0.98 },    { "formulaID": "6", "versionID": 1, "yieldFactor": 0.95 },    { "formulaID": "7", "versionID": 1, "yieldFactor": 0.85 }];并尝试以编程方式创建此输出：const result =[    { "formulaID": "7", "versionID": 1, "yieldFactor": 0.85, "outputName": "" },    { "formulaID": "4", "versionID": 1, "yieldFactor": 0.93, "outputName": "Hazelnut Creamer" },    { "formulaID": "4", "versionID": 2, "yieldFactor": 0.98, "outputName": "" },    { "formulaID": "6", "versionID": 1, "yieldFactor": 0.95, "outputName": "White Milk 2%" }];在这篇文章的帮助下，我编写了以下代码：const result = yields.map(yld => ({    formulaID: yld.formulaID,    versionID: yld.versionID,    yieldFactor: yld.yieldFactor,    outputName: formulas.filter(f => (f.formulaID + '-' + f.versionID).includes(yld.formulaID + '-' + yld.versionID))}));console.log(result);它接近预期的结果，但我不确定如何仅隔离outputName. 在其当前状态下，它给出了找到匹配项的整个数组。对于原始源数据数组之间不匹配的位置，如何仅显示outputName匹配项和空字符串？outputName编辑 - 当前输出如下所示：

Answer 1

Using.filter将始终返回满足您条件的公式数组，因此您需要先检查它是否给出结果，然后仅从.outputName其结果中检索。

可能是这样的：

const result = yields.map(yld => {

  const targetFormulas = formulas.filter(f => (f.formulaID + '-' + f.versionID).includes(yld.formulaID + '-' + yld.versionID));

  const outputName = targetFormulas.length ? targetFormulas.map(f => f.outputName).join(',') : ''

  return {

    formulaID: yld.formulaID,

    versionID: yld.versionID,

    yieldFactor: yld.yieldFactor,

    outputName

  }

});

我用a.join(',')来返回用逗号分隔的outputNames，如果有超过1个。

如果你确定只会返回1个，你可以这样做 targetFormulas.map(f => f.outputName)[0]

这将返回以下结果

[

   {

      "formulaID":"4",

      "versionID":1,

      "yieldFactor":0.93,

      "outputName":"Hazelnut Creamer"

   },

   {

      "formulaID":"4",

      "versionID":2,

      "yieldFactor":0.98,

      "outputName":""

   },

   {

      "formulaID":"6",

      "versionID":1,

      "yieldFactor":0.95,

      "outputName":"White Milk 2%"

   },

   {

      "formulaID":"7",

      "versionID":1,

      "yieldFactor":0.85,

      "outputName":""

   }

]