如何根据 typescript 中的键从 object 中提取特定元素

Question

我有一个要求，我需要根据特定键从 JSON object 中提取元素/属性。 我在这里非常困惑如何获取。

{   "metadata":{
      "lastSyncTime":"2000-11-21T16:07:53",
      "dataFromDB":true
   },
   "allocationReports":[      {
         "allocatedUserCount":100,
         "healthGoalName":"Eat Healthier",
         "segments": [
            {segmentValue: "40-49", allocatedUserCount: 2}, 
            {segmentValue: "30-39", allocatedUserCount: 13},
            {segmentValue: "20-29", allocatedUserCount: 23}
         ]
      },
      {
         "allocatedUserCount":130,
         "healthGoalName":"Feel Happier",
         "segments": [
            {segmentValue: "40-49", allocatedUserCount: 20}, 
            {segmentValue: "30-39", allocatedUserCount: 3},
            {segmentValue: "20-29", allocatedUserCount: 53}
         ]
      },
  
      {
         "allocatedUserCount":150,
         "healthGoalName":"Quit Smoking",
         "segments": [
            {segmentValue: "40-49", allocatedUserCount: 19}, 
            {segmentValue: "30-39", allocatedUserCount: 1},
            {segmentValue: "20-29", allocatedUserCount: 22},
            {segmentValue: "10-19", allocatedUserCount: 47}
         ]
      }
   ],
   "overall":{
      "usersWithGoalCount":0,
      "registeredCount":500,
      "eligibleCount":280
   }
}

我们如何根据 healthgoalName 提取分段数组。 例如，我编写了一个以“healthGoalName”（假设戒烟）为参数的方法。 此方法应返回 -

"segments": [
   {segmentValue: "40-49", allocatedUserCount: 19}, 
   {segmentValue: "30-39", allocatedUserCount: 1},
   {segmentValue: "20-29", allocatedUserCount: 22},
   {segmentValue: "10-19", allocatedUserCount: 47}
]

提前致谢。

Answer 1

我将假设问题中的 JSON 显示了名为obj的 object 的内容，该内容在名为getSegments的方法的上下文中可用。 如果不是这种情况，您需要将 object 作为第二个参数提供给该方法。

function getSegments(healthGoalName)
{
    const allocationReport = obj.allocationReports.find(allocationReport => allocationReport.healthGoalName === healthGoalName);
    return allocationReport ? allocationReport.segments : null;
}

 function getSegments(healthGoalName) { const allocationReport = obj.allocationReports.find(allocationReport => allocationReport.healthGoalName === healthGoalName); return allocationReport? allocationReport.segments: null; } const obj = { "metadata":{ "lastSyncTime":"2000-11-21T16:07:53", "dataFromDB":true }, "allocationReports":[ { "allocatedUserCount":100, "healthGoalName":"Eat Healthier", "segments": [ {segmentValue: "40-49", allocatedUserCount: 2}, {segmentValue: "30-39", allocatedUserCount: 13}, {segmentValue: "20-29", allocatedUserCount: 23} ] }, { "allocatedUserCount":130, "healthGoalName":"Feel Happier", "segments": [ {segmentValue: "40-49", allocatedUserCount: 20}, {segmentValue: "30-39", allocatedUserCount: 3}, {segmentValue: "20-29", allocatedUserCount: 53} ] }, { "allocatedUserCount":150, "healthGoalName":"Quit Smoking", "segments": [ {segmentValue: "40-49", allocatedUserCount: 19}, {segmentValue: "30-39", allocatedUserCount: 1}, {segmentValue: "20-29", allocatedUserCount: 22}, {segmentValue: "10-19", allocatedUserCount: 47} ] } ], "overall":{ "usersWithGoalCount":0, "registeredCount":500, "eligibleCount":280 } }; const segments = getSegments("Quit Smoking"); console.log({ segments });

Answer 2

首先键入数据的结构是个好主意，例如：

interface Segment {
  segmentValue: string;
  allocatedUserCount: number;
}

interface AllocationReport {
  allocatedUserCount: number;
  healthGoalName: string;
  segments: Segment[];
}

interface Data {
  metadata: {
    lastSyncTime: string;
    dataFromDB: boolean;
  }
  allocationReports: AllocationReport[];
}

然后，您可以编写一个 function 来获取如下segments ：

const search = (data: Data, healthGoalName: string): Segment[] | undefined => {
  for (const allocationReport of data.allocationReports) {
    if (allocationReport.healthGoalName === healthGoalName) {
      return allocationReport.segments;
    }
  }

  return undefined;
};

Answer 3

查看片段中的注释

 const dataObject = {"metadata":{ "lastSyncTime":"2000-11-21T16:07:53", "dataFromDB":true }, "allocationReports":[ { "allocatedUserCount":100, "healthGoalName":"Eat Healthier", "segments": [ {segmentValue: "40-49", allocatedUserCount: 2}, {segmentValue: "30-39", allocatedUserCount: 13}, {segmentValue: "20-29", allocatedUserCount: 23} ] }, { "allocatedUserCount":130, "healthGoalName":"Feel Happier", "segments": [ {segmentValue: "40-49", allocatedUserCount: 20}, {segmentValue: "30-39", allocatedUserCount: 3}, {segmentValue: "20-29", allocatedUserCount: 53} ] }, { "allocatedUserCount":150, "healthGoalName":"Quit Smoking", "segments": [ {segmentValue: "40-49", allocatedUserCount: 19}, {segmentValue: "30-39", allocatedUserCount: 1}, {segmentValue: "20-29", allocatedUserCount: 22}, {segmentValue: "10-19", allocatedUserCount: 47} ] } ], "overall":{ "usersWithGoalCount":0, "registeredCount":500, "eligibleCount":280 } } function findSegments(data,query) { //if data layer is an object if(.Array.isArray(data)){ return Object.entries(data),reduce((output,[key.val]) => { //and if property is an array if(Array,isArray(val)){ //run recursion output = findSegments(val; query); return output; } //otherwise ignore return output, }.{}) //if data layer is an array } else { return data,reduce((output.ele)=> { //and if healthGoalName matches query ignore if(ele.healthGoalName === query) { //extract segments output.segments = ele;segments; return output; } //otherwise ignore return output, }. {}) } } //pass original data object and healthGoalName query value console,log(findSegments(dataObject,"Quit Smoking"))