json.Marshal 映射到 JSON 数组

Question

当我尝试 Marshal 地图时， json.Marshal 返回：{"Map Key":"Map Value"}...这是正常行为。但我可以将其编组为：{"Map":[{"Name":"Map Key","Date":"Map Value"},{"Name":"Map Key2","Date":"Map Value2"}]}

Answer 1

您可以定义一个自定义json.Marshaler接口来执行此操作，例如：

type mapInfo struct {

    Name string `json:"name"`

    Date string `json:"date"`

}

type CustomMap map[string]string

func (cm CustomMap) MarshalJSON() ([]byte, error) {

    // if you want to optimize you can use a bytes.Buffer and write the strings out yourself.

    var out struct {

        Map []mapInfo `json:"map"`

    }

    for k, v := range cm {

        out.Map = append(out.Map, mapInfo{k, v})

    }

    return json.Marshal(out)

}

func (cm CustomMap) UnmarshalJSON(b []byte) (err error) {

    var out struct {

        Map []mapInfo `json:"map"`

    }

    if err = json.Unmarshal(b, &out); err != nil {

        return

    }

    for _, v := range out.Map {

        cm[v.Name] = v.Date

    }

    return

}

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