JavaScript过滤三级嵌套数组：获取含指定生效日期的gList元素

我有一组三级嵌套的JSON数据，需要筛选出所有满足条件的gList元素——该元素的productList数组中存在effectiveDate为"12/12/2023"的项，也可以只获取首个匹配结果。

示例数据 #

var data = {"cList": [{"Id": "111111", "Number": "176116", "Name": "Test", "gList": [{"gNumber": "123456", "productList": [{"spn": "2118593162", "pno": "2118593163", "effectiveDate": "12/12/2023", "partB": false, "id": ""}, {"spn": "2131493390", "pno": "2131493390", "effectiveDate": "01/01/2020", "partB": false, "id": ""}, {"spn": "2100171794", "pno": "2100171794", "benefitPlanType": "Wellness Programs", "effectiveDate": "01/01/2023", "partB": false, "id": ""}]}, {"gNumber": "10422798", "productList": [{"spn": "2118593162", "pno": "2118593163", "effectiveDate": "01/01/2022", "partB": false, "id": ""}, {"spn": "2131493390", "pno": "2131493390", "effectiveDate": "01/01/2020", "partB": false, "id": ""}, {"spn": "2100171794", "pno": "2100171794", "benefitPlanType": "Wellness Programs", "effectiveDate": "01/01/2023", "partB": false, "id": ""}]}, {"gNumber": "10422700", "productList": [{"spn": "2118593162", "pno": "2118593163", "effectiveDate": "01/01/2023", "partB": false, "id": ""}, {"spn": "2131493390", "pno": "2131493390", "effectiveDate": "01/01/2020", "partB": false, "id": ""}, {"spn": "2100171794", "pno": "2100171794", "benefitPlanType": "Wellness Programs", "effectiveDate": "01/01/2023"}]}]}, {"Id": "222", "Number": "176116", "Name": "Test", "gList": [{"gNumber": "1234567", "productList": [{"spn": "2118593162", "pno": "2118593163", "effectiveDate": "12/12/2010", "partB": false, "id": ""}, {"spn": "2131493390", "pno": "2131493390", "effectiveDate": "01/01/2020", "partB": false, "id": ""}, {"spn": "2100171794", "pno": "2100171794", "benefitPlanType": "Wellness Programs", "effectiveDate": "01/01/2023", "partB": false, "id": ""}]}, {"gNumber": "10422798", "productList": [{"spn": "2118593162", "pno": "2118593163", "effectiveDate": "01/01/2022", "partB": false, "id": ""}, {"spn": "2131493390", "pno": "2131493390", "effectiveDate": "01/01/2020", "partB": false, "id": ""}, {"spn": "2100171794", "pno": "2100171794", "benefitPlanType": "Wellness Programs", "effectiveDate": "01/01/2023", "partB": false, "id": ""}]}, {"gNumber": "10422795", "productList": [{"spn": "2118593162", "pno": "2118593163", "effectiveDate": "12/12/2023", "partB": false, "id": ""}, {"spn": "2131493390", "pno": "2131493390", "effectiveDate": "01/01/2020", "partB": false, "id": ""}, {"spn": "2100171794", "pno": "2100171794", "benefitPlanType": "Wellness Programs", "effectiveDate": "01/01/2023"}]}]}]};

尝试的错误代码 #

const filteredClientList = data.cList.filter(
    (cListElement) =>
        cListElement.gList.find(
            (gListElement) =>
                gListElement.productList.filter((productListElement) => productListElement.effectiveDate === "12/12/2023"),
        ),
);
console.log("filteredClientList", JSON.stringify(filteredClientList));

预期输出 #

[  
  {    
    "gNumber": "123456",    
    "productList": [      
      {        
        "spn": "2118593162",        
        "pno": "2118593163",        
        "effectiveDate": "12/12/2023",        
        "partB": false,        
        "id": ""      
      },      
      {        
        "spn": "2131493390",        
        "pno": "2131493390",        
        "effectiveDate": "01/01/2020",        
        "partB": false,        
        "id": ""      
      },      
      {        
        "spn": "2100171794",        
        "pno": "2100171794",        
        "benefitPlanType": "Wellness Programs",        
        "effectiveDate": "01/01/2023",        
        "partB": false,        
        "id": ""      
    }    
  ]  
  },  
  {    
    "gNumber": "10422795",    
    "productList": [      
      {        
        "spn": "2118593162",        
        "pno": "2118593163",        
        "effectiveDate": "12/12/2023",        
        "partB": false,        
        "id": ""      
      },      
      {        
        "spn": "2131493390",        
        "pno": "2131493390",        
        "effectiveDate": "01/01/2020",        
        "partB": false,        
        "id": ""      
      },      
      {        
        "spn": "2100171794",        
        "pno": "2100171794",        
        "benefitPlanType": "Wellness Programs",        
        "effectiveDate": "01/01/2023"      
      }    
    ]  
  }
]

问题分析与解决方案 #

你的代码有两个核心问题：

1. 最终返回的是cList元素，而非直接返回符合条件的gList元素，和预期输出结构不符；
2. 判断productList时用了filter，它会返回一个数组，虽然非空数组在布尔判断中为true，但some方法更适合这个场景——它只要找到第一个匹配项就会停止遍历，效率更高。

方案1：获取所有符合条件的gList元素 #

const filteredGLists = data.cList.flatMap(cItem => 
  // 对每个cItem的gList进行筛选，保留productList中存在指定日期的项
  cItem.gList.filter(gItem => 
    gItem.productList.some(product => product.effectiveDate === "12/12/2023")
  )
);

console.log("filteredGLists", JSON.stringify(filteredGLists, null, 2));

方案2：仅获取首个匹配的gList元素 #

const firstMatch = data.cList
  // 先把所有cItem中的gList展开成一个一维数组
  .flatMap(cItem => cItem.gList)
  // 找到第一个符合条件的gList元素
  .find(gItem => 
    gItem.productList.some(product => product.effectiveDate === "12/12/2023")
  );

console.log("firstMatch", JSON.stringify(firstMatch, null, 2));

内容的提问来源于stack exchange，提问作者RSKMR