修改服务字段类型

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Words count in article: 499 | Reading time ≈ 2

背景

接口返回的是geojson格式，但是使用GeojsonLayer加载的时候，高亮的坐标有问题。排查发现，是接口返回的坐标全是string类型。

所以要写一个方法，把string类型的坐标转换为double类型，其他的数据保持不变。

转换的格式如下：

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{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {
        "ID": "1"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [
          "120.98058226222103",
          "31.19176762858661"
        ]
      }
    },
    {
      "type": "Feature",
      "properties": {
        "ID": "5"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [
          "121.0442694",
          "31.27477222"
        ]
      }
    }
  ]
}
->
{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {
        "ID": "1"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [
          120.98058226222103,
          31.19176762858661
        ]
      }
    },
    {
      "type": "Feature",
      "properties": {
        "ID": "5"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [
          121.0442694,
          31.27477222
        ]
      }
    }
  ]
}

代码

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<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Ramda</title>

  <style>
    textarea {
      width: 100%;
    }
  </style>
  <script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.27.0/ramda.min.js"></script>
</head>

<body onload="workFlow()">
  <textarea cols="100" rows="50"></textarea>

  <script>
    const getResponse = () => {
      return {
        "type": "FeatureCollection",
        "features": [{
            "type": "Feature",
            "properties": {
              "ID": "1",
            },
            "geometry": {
              "type": "Point",
              "coordinates": [
                "120.98058226222103",
                "31.19176762858661"
              ]
            }
          },
          {
            "type": "Feature",
            "properties": {
              "ID": "5",
            },
            "geometry": {
              "type": "Point",
              "coordinates": [
                "121.0442694",
                "31.27477222"
              ]
            }
          }
        ]
      };
    }

    const workFlow = () => {
      const response = getResponse();
      const featuresLens = R.lensProp('features'); // 使用透镜获取features属性
      const coordinatesLens = R.lensPath(['geometry', 'coordinates']); // 使用透镜获取coordinates属性
      const coordinates2num = R.map(Number); // 把坐标值从字符串转为数字
      const overFeatures = R.over(coordinatesLens, coordinates2num); // 修改features中coordinates的值
      const mapFeatures = R.map(overFeatures); // 遍历features
      const overResponse = R.over(featuresLens, mapFeatures); // 修改response中features的值
      const result = overResponse(response);
      print(response);
    }

    // 打印结果相关
    const setTextarea = str => {
      document.getElementsByTagName("textarea")[0].value = str;
    };

    const stringify = json => JSON.stringify(json, null, "  ");

    const print = R.compose(
      setTextarea,
      stringify
    );
    // 打印结果相关
  </script>
</body>

</html>

结束语

按平时ES6的写法，循环遍历，然后修改值。破坏了数据不变。

ramda的写法明显要更复杂一些。