有没有办法从 React Native 中的 JSON 文件中获取所需的信息答案

【问题标题】：Is there a way to fetch needed information from JSON file in React Native有没有办法从 React Native 中的 JSON 文件中获取所需的信息
【发布时间】：2021-07-19 10:57:49
【问题描述】：

我正在使用 COVID-19 API (https://api.covidactnow.org/v2/counties.json?apiKey=) 来记录各种信息，例如美国每个县的病例数和死亡人数。在我的 React Native 应用程序中，我检索了用户的位置，更具体地说，是用户所在的县、州和国家。在这种情况下，我将用户的县名存储在countyName 中。我想根据 countyName 的内容从 JSON 文件中获取具体病例和死亡人数。我在下面的 JSON 文件中有一个县的 sn-p。我在想我可以进入数组的索引和实际值，然后获取病例和死亡人数。

[
  {
    "fips": "02013",
    "country": "US",
    "state": "AK",
    "county": "Aleutians East Borough",
    "level": "county",
    "lat": null,
    "locationId": "iso1:us#iso2:us-ak#fips:02013",
    "long": null,
    "population": 3337,
    "metrics": {
      "testPositivityRatio": null,
      "testPositivityRatioDetails": {
        "source": "other"
      },
      "caseDensity": 0,
      "contactTracerCapacityRatio": null,
      "infectionRate": 4.71887277063,
      "infectionRateCI90": 1.1615979428900003,
      "icuHeadroomRatio": null,
      "icuHeadroomDetails": null,
      "icuCapacityRatio": null,
      "vaccinationsInitiatedRatio": null,
      "vaccinationsCompletedRatio": 0.27509739286784535
    },
    "riskLevels": {
      "overall": 0,
      "testPositivityRatio": 4,
      "caseDensity": 0,
      "contactTracerCapacityRatio": 4,
      "infectionRate": 3,
      "icuHeadroomRatio": 4,
      "icuCapacityRatio": 4
    },
    "actuals": {
      "cases": 363,
      "deaths": 2,
      "positiveTests": null,
      "negativeTests": null,
      "contactTracers": null,
      "hospitalBeds": {
        "capacity": null,
        "currentUsageTotal": null,
        "currentUsageCovid": null,
        "typicalUsageRate": null
      },
      "icuBeds": {
        "capacity": null,
        "currentUsageTotal": null,
        "currentUsageCovid": null,
        "typicalUsageRate": null
      },
      "newCases": 0,
      "newDeaths": 0,
      "vaccinesDistributed": null,
      "vaccinationsInitiated": null,
      "vaccinationsCompleted": 918,
      "vaccinesAdministered": null,
      "vaccinesAdministeredDemographics": null,
      "vaccinationsInitiatedDemographics": null
    },
    "annotations": {
      "cases": {
        "sources": [
          {
            "type": "NYTimes",
            "url": "https://github.com/nytimes/covid-19-data",
            "name": "The New York Times"
          }
        ],
        "anomalies": []
      },
      "deaths": {
        "sources": [
          {
            "type": "NYTimes",
            "url": "https://github.com/nytimes/covid-19-data",
            "name": "The New York Times"
          }
        ],
        "anomalies": []
      },
      "positiveTests": null,
      "negativeTests": null,
      "contactTracers": null,
      "hospitalBeds": null,
      "icuBeds": null,
      "newCases": null,
      "newDeaths": null,
      "vaccinesDistributed": null,
      "vaccinationsInitiated": null,
      "vaccinationsCompleted": {
        "sources": [
          {
            "type": "other",
            "url": "https://covid.cdc.gov/covid-data-tracker/#county-view",
            "name": "Centers for Disease Control and Prevention"
          }
        ],
        "anomalies": []
      },
      "vaccinesAdministered": null,
      "testPositivityRatio": null,
      "caseDensity": {
        "sources": [
          {
            "type": "NYTimes",
            "url": "https://github.com/nytimes/covid-19-data",
            "name": "The New York Times"
          }
        ],
        "anomalies": []
      },
      "contactTracerCapacityRatio": null,
      "infectionRate": {
        "sources": [
          {
            "type": "NYTimes",
            "url": "https://github.com/nytimes/covid-19-data",
            "name": "The New York Times"
          }
        ],
        "anomalies": []
      },
      "infectionRateCI90": {
        "sources": [
          {
            "type": "NYTimes",
            "url": "https://github.com/nytimes/covid-19-data",
            "name": "The New York Times"
          }
        ],
        "anomalies": []
      },
      "icuHeadroomRatio": null,
      "icuCapacityRatio": null,
      "vaccinationsInitiatedRatio": null,
      "vaccinationsCompletedRatio": null
    },
    "lastUpdatedDate": "2021-04-26",
    "url": "https://covidactnow.org/us/alaska-ak/county/aleutians_east_borough"
  },

【问题讨论】：

标签： json typescript react-native api fetch

【解决方案1】：

如果您只对特定县感兴趣，可以使用an endpoint for this in the API。只需要查询这个，就不需要对获取的数据做进一步的过滤了：

https://api.covidactnow.org/v2/county/{fips}.json?apiKey=YOUR_KEY_HERE

【讨论】：

谢谢你！我以前没有注意到。

【解决方案2】：

您从 API 获得的 JSON 格式响应是一个对象数组。要从对象数组中获取死亡人数和病例数，您需要执行以下操作：

    const response= [
        {
        "fips": "02013",
        "country": "US",
        "state": "AK",
        "county": "Aleutians East Borough",
        "level": "county",
        "lat": null,
        "locationId": "iso1:us#iso2:us-ak#fips:02013",
        "long": null,
        "population": 3337,
        "metrics": {
          "testPositivityRatio": null,
          "testPositivityRatioDetails": {
            "source": "other"
          },
          "caseDensity": 0,
          "contactTracerCapacityRatio": null,
          "infectionRate": 4.71887277063,
          "infectionRateCI90": 1.1615979428900003,
          "icuHeadroomRatio": null,
          "icuHeadroomDetails": null,
          "icuCapacityRatio": null,
          "vaccinationsInitiatedRatio": null,
          "vaccinationsCompletedRatio": 0.27509739286784535
         },
         "riskLevels": {
         "overall": 0,
          "testPositivityRatio": 4,
          "caseDensity": 0,
          "contactTracerCapacityRatio": 4,
          "infectionRate": 3,
          "icuHeadroomRatio": 4,
          "icuCapacityRatio": 4
         },
         "actuals": {
         "cases": 363,
          "deaths": 2,
          "positiveTests": null,
          "negativeTests": null,
          "contactTracers": null,
          "hospitalBeds": {
            "capacity": null,
            "currentUsageTotal": null,
            "currentUsageCovid": null,
            "typicalUsageRate": null
          },
          "icuBeds": {
            "capacity": null,
            "currentUsageTotal": null,
            "currentUsageCovid": null,
            "typicalUsageRate": null
          },
          "newCases": 0,
          "newDeaths": 0,
          "vaccinesDistributed": null,
          "vaccinationsInitiated": null,
          "vaccinationsCompleted": 918,
          "vaccinesAdministered": null,
          "vaccinesAdministeredDemographics": null,
          "vaccinationsInitiatedDemographics": null
        },
        "annotations": {
          "cases": {
            "sources": [
              {
                "type": "NYTimes",
                "url": "https://github.com/nytimes/covid-19-data",
                "name": "The New York Times"
              }
            ],
            "anomalies": []
          },
          "deaths": {
            "sources": [
              {
                "type": "NYTimes",
                "url": "https://github.com/nytimes/covid-19-data",
                "name": "The New York Times"
              }
            ],
            "anomalies": []
          },
          "positiveTests": null,
          "negativeTests": null,
          "contactTracers": null,
          "hospitalBeds": null,
          "icuBeds": null,
          "newCases": null,
          "newDeaths": null,
          "vaccinesDistributed": null,
          "vaccinationsInitiated": null,
          "vaccinationsCompleted": {
            "sources": [
              {
                "type": "other",
                "url": "https://covid.cdc.gov/covid-data-tracker/#county-view",
                "name": "Centers for Disease Control and Prevention"
              }
            ],
            "anomalies": []
          },
          "vaccinesAdministered": null,
          "testPositivityRatio": null,
          "caseDensity": {
            "sources": [
              {
                "type": "NYTimes",
                "url": "https://github.com/nytimes/covid-19-data",
                "name": "The New York Times"
              }
            ],
            "anomalies": []
          },
          "contactTracerCapacityRatio": null,
          "infectionRate": {
            "sources": [
              {
                "type": "NYTimes",
                "url": "https://github.com/nytimes/covid-19-data",
                "name": "The New York Times"
              }
            ],
            "anomalies": []
          },
          "infectionRateCI90": {
            "sources": [
              {
                "type": "NYTimes",
                "url": "https://github.com/nytimes/covid-19-data",
                "name": "The New York Times"
              }
            ],
            "anomalies": []
          },
          "icuHeadroomRatio": null,
          "icuCapacityRatio": null,
          "vaccinationsInitiatedRatio": null,
          "vaccinationsCompletedRatio": null
        },
        "lastUpdatedDate": "2021-04-26",
        "url": "https://covidactnow.org/us/alaska-ak/county/aleutians_east_borough"
      }
    ]
    const enteredCountryName = "US";
    //Getting the required country name from the array of objects using filter method
    const countryArray = response.filter(item => item.country === enteredCountryName)
    const noOfDeaths = countryArray[0].actuals.deaths;
    const noOfCases = countryArray[0].actuals.cases;
    console.log({noOfDeaths, noOfCases})

【讨论】：