JavaScript实现JSON按区-市镇-教区三级嵌套分组

• 目标是构建三级嵌套的葡萄牙行政区划JSON文件，层级关系为：区（district） → 市镇（municipality） → 教区（parish）
• 期望输出结构示例：

{
  "district": "Aveiro",
  "OfficialCodeDistrict": "01",
  "municipalities": [
    {
      "municipality": "Arouca",
      "OfficialCodeMunicipality": "0104",
      "parishes": [
        {
          "parish": "Fermedo",
          "OfficialCodeParish": {}
        },
        {
          "parish": "Várzea",
          "OfficialCodeParish": "010420"
        },
        {
          "parish": "Escariz",
          "OfficialCodeParish": "010409"
        },
        {
          "parish": "Mansores",
          "OfficialCodeParish": "010413"
        }
      ]
    },
    {
      "municipality": "Águeda",
      "OfficialCodeMunicipality": "0101",
      "parishes": [
        {
          "parish": "Fermentelos",
          "OfficialCodeParish": "010109"
        },
        {
          "parish": "Préstimo e Macieira de Alcoba",
          "OfficialCodeParish": "010127"
        }
      ]
    }
  ]
}

• 已完成第一步：将原始数据按区做一级分组，实现代码如下：

const result = Object.entries(locations.reduce((acc, { OfficialCodeDistrict, OfficialNameDistrict, OfficialCodeMunicipality, OfficialNameMunicipality, OfficialNameParish, Type  }) => {
        acc[OfficialNameDistrict] = (acc[OfficialNameDistrict] || []);
        acc[OfficialNameDistrict].push({ OfficialCodeDistrict, OfficialCodeMunicipality, OfficialNameMunicipality, OfficialNameParish, Type });
        return acc;
    }, {})).map(([key, value]) => ({ district: key, municipalities: value }));

console.log(result);

• 当前进展：已写出遍历每个区、对区内数据按市镇做二级分组的循环逻辑，可以独立生成每个区下按市镇归类的结果，但不知道如何将二级分组结果合并回一级分组的区对象中，现有循环代码如下：

let counter = 0;

// 遍历所有区，对区内市镇做分组
while (counter < result.length){

    result2 = Object.entries(result[counter]['municipalities'].reduce((acc, { OfficialCodeMunicipality, OfficialNameMunicipality, OfficialNameParish, Type  }) => {
        acc[OfficialNameMunicipality] = (acc[OfficialNameMunicipality] || []);
        acc[OfficialNameMunicipality].push({ OfficialCodeMunicipality, OfficialNameParish, Type });
        return acc;
    }, {})).map(([key, value]) => ({ municipality: key, parishes: value }));

    console.log(result2);
    // 目前已经可以为每个区生成独立的按市镇分组的JSON对象，例如Portalegre区可生成包含15个市镇条目的对象，所有区都能正常生成对应分组结果，但还未达到最终效果

    counter++;
}

不需要单独声明result2存储临时分组结果，遍历区对象时直接把二级分组得到的市镇列表赋值给当前区对象的municipalities属性即可，同时补全各级缺失的官方编码字段、修正教区层级的字段映射，完整实现代码如下：

// 一级分组：按区归类
const result = Object.entries(
  locations.reduce((acc, curr) => {
    const { OfficialCodeDistrict, OfficialNameDistrict } = curr;
    acc[OfficialNameDistrict] = acc[OfficialNameDistrict] || [];
    acc[OfficialNameDistrict].push(curr);
    return acc;
  }, {})
).map(([districtName, districtEntries]) => {
  // 提取当前区的官方编码（同一区编码一致，取第一条即可）
  const OfficialCodeDistrict = districtEntries[0].OfficialCodeDistrict;

  // 二级分组：按市镇归类
  const municipalities = Object.entries(
    districtEntries.reduce((acc, curr) => {
      const { OfficialCodeMunicipality, OfficialNameMunicipality } = curr;
      acc[OfficialNameMunicipality] = acc[OfficialNameMunicipality] || [];
      acc[OfficialNameMunicipality].push(curr);
      return acc;
    }, {})
  ).map(([municipalityName, municipalityEntries]) => {
    // 提取当前市镇的官方编码（同一市镇编码一致，取第一条即可）
    const OfficialCodeMunicipality = municipalityEntries[0].OfficialCodeMunicipality;

    // 组装当前市镇下的所有教区列表
    const parishes = municipalityEntries.map(entry => ({
      parish: entry.OfficialNameParish,
      OfficialCodeParish: entry.OfficialCodeParish || {}
    }));

    return {
      municipality: municipalityName,
      OfficialCodeMunicipality,
      parishes
    };
  });

  return {
    district: districtName,
    OfficialCodeDistrict,
    municipalities
  };
});

console.log(result);

代码说明：

• 同一区、同一市镇的官方编码是固定值，不需要在分组时重复存储，直接取分组下第一条数据的对应编码字段即可
• 教区层级直接映射原始数据的教区名称和教区编码，缺失编码的场景默认赋值为空对象，和示例结构保持一致
• 去掉了冗余的while循环和临时变量，直接在一级分组的map遍历中完成二级分组，逻辑更连贯

内容的提问来源于stack exchange，提问作者António Lima