javascript - 将嵌套 JSON 数组转换为平面 JSON 数组

Question

我有一个嵌套的 JSON 数组，它从 mongoDB 查询中获取，我想将其转换为平面 JSON。我正在使用嵌套的 mondo 文档，但我想以更易读的方式显示数据。我的 JSON 具有以下结构:

[{
     "country": "Country A",
     "regions": [{
            "region": "region A1",
            "cities": [{
                    "city": "city A11"
                },
                {
                 "city": "city A12"
                }
            ]
            },
            {
                "region": "region A2",
                "cities": [{
                        "city": "city A21"
                    },
                    {
                        "city": "city A22"
                    }
                ]
            }
        ]
    },
    {
        "country": "Country B",
        "regions": [{
                "region": "region B1",
                "cities": [{
                        "city": "city B11"
                    },
                    {
                        "city": "city B12"
                    }
                ]
            },
            {
                "region": "region B2",
                "cities": [{
                        "city": "city B21"
                    },
                    {
                        "city": "city B22"
                    }
                ]
            }
        ]
    }
]

我只想显示重要信息，而不是嵌套数组的结构。我如何在 Javascript 中修改我的数据以获得以下结果。

[
  {
    "country": "Country A",
    "region":"Region A1",
    "city": "City A11"
  },
   {
    "country": "Country A",
    "region":"Region A1",
    "city": "City A12"
  },
  -------------
   {
    "country": "Country B",
    "region":"Region B1",
    "city": "City B11"
  },
  -----------
   {
    "country": "Country B",
    "region":"Region B2",
    "city": "City B22"
  }
]

达到这个结果的最简单方法是什么？

Answer 1

最简单的方法是循环并创建一个数组。您可以使用reduce()来做到这一点:

let arr = [{"country": "Country A","regions": [{"region": "region A1","cities": [{"city": "city A11"},{"city": "city A12"}]},{"region": "region A2","cities": [{"city": "city A21"},{"city": "city A22"}]}]},{"country": "Country B","regions": [{"region": "region B1","cities": [{"city": "city B11"},{"city": "city B12"}]},{"region": "region B2","cities": [{"city": "city B21"},{"city": "city B22"}]}]}]

let flat = arr.reduce((arr, {country, regions}) => {
    regions.forEach(({region, cities}) => {
        cities.forEach(({city}) => {
            arr.push({country, region, city})
        })
    })
    return arr
}, [])
console.log(flat)