Array.filter没有返回所需的输出

Question

我有嵌套的数据数组。我可以根据自己的条件获取第一组数据，但是当我在此结果集上应用array.filter时，它并没有给我预期的结果。

下面是数据数组：

get_in

首先，我已将以下array.filter应用到基于日期的FailureDetails：

[]

这给了我带有描述的失败详细信息，但是现在在原因ID上，我想获取描述，但是它不起作用并将结果返回为“ undefined”

谁能建议我要去哪里错了？

Answer 1

您需要执行value.Date而不是data.Date，因为value引用了data数组中的每个对象：

var data = [{
  "Date": "02/04/2019",
  "Total": "1000",
  "Success": "850",
  "Failure": "150",
  "FailureDeatils": [{
    "name": "Reason1",
    "Count": 2,
    "Description": [{
      "DescriptionID": "01",
      "Status": "Failure Point1"
    }, {
      "DescriptionID": "01",
      "Status": "Failure Point1"
    }]
  }, {
    "name": "Reason2",
    "Count": 6,
    "Description": [{
      "DescriptionID": "01",
      "Status": "Failure Point1"
    }, {
      "DescriptionID": "01",
      "Status": "Failure Point1"
    }]
  }]
}, {
  "Date": "03/04/2019",
  "Total": "800",
  "Success": "750",
  "Failure": "150",
  "FailureDeatils": [{
    "name": "Reason1",
    "Count": 3,
    "Description": [{
      "DescriptionID": "01",
      "Status": "Failure Point1"
    }, {
      "DescriptionID": "01",
      "Status": "Failure Point1"
    }]
  }, {
    "name": "Reason2",
    "Count": 1,
    "Description": [{
      "DescriptionID": "01",
      "Status": "Failure Point1"
    }, {
      "DescriptionID": "01",
      "Status": "Failure Point1"
    }]
  }]
}];


var filtered = data
  .filter(value => value.Date == "02/04/2019")
  .map(e => e.FailureDeatils);
console.log(filtered);

Answer 2

看起来您的意思是value.Date而不是data.Date。

.filter(value => value.Date == "02/04/2019")

Answer 3

您在过滤器中输入了错误的变量：

应为：

const filtered = data.filter(value => value.Date == "02/04/2019").map(e => e.FailureDeatils);

而非：

const filtered = data.filter(value => data.Date == "02/04/2019").map(e => e.FailureDeatils);

以下是根据您的代码提供的有效的示例：

const object = {
        "data": [
          {
            "Date": "02/04/2019",
            "Total": "1000",
            "Success": "850",
            "Failure": "150",
            "FailureDeatils": [
              {
                "name": "Reason1",
                "Count": 2,
                "Description": [
                  {
                    "DescriptionID": "01",
                    "Status": "Failure Point1"
                  },
                  {
                    "DescriptionID": "01",
                    "Status": "Failure Point1"
                  }
                ]
              },
              {
                "name": "Reason2",
                "Count": 6,
                "Description": [
                  {
                    "DescriptionID": "01",
                    "Status": "Failure Point1"
                  },
                  {
                    "DescriptionID": "01",
                    "Status": "Failure Point1"
                  }
                ]
              }
            ]
          },
          {
            "Date": "03/04/2019",
            "Total": "800",
            "Success": "750",
            "Failure": "150",
            "FailureDeatils": [
              {
                "name": "Reason1",
                "Count": 3,
                "Description": [
                  {
                    "DescriptionID": "01",
                    "Status": "Failure Point1"
                  },
                  {
                    "DescriptionID": "01",
                    "Status": "Failure Point1"
                  }
                ]
              },
              {
                "name": "Reason2",
                "Count": 1,
                "Description": [
                  {
                    "DescriptionID": "01",
                    "Status": "Failure Point1"
                  },
                  {
                    "DescriptionID": "01",
                    "Status": "Failure Point1"
                  }
                ]
              }
            ]
          }
        ]
      }
    
    const filtered = object.data.filter(value => value.Date == "02/04/2019").map(e => e.FailureDeatils);
    
    console.log(filtered);