JSON将整数字段解组为字符串

要处理大型结构,可以使用嵌入。

更新为不丢弃以前可能设置的字段值。

func (t *T) UnmarshalJSON(d []byte) error {
    type T2 T // create new type with same structure as T but without its method set!
    x := struct{
        T2 // embed
        Foo json.Number `json:"foo"`
    }{T2: T2(*t)} // don't forget this, if you do and 't' already has some fields set you would lose them

    if err := json.Unmarshal(d, &x); err != nil {
        return err
    }
    *t = T(x.T2)
    t.Foo = x.Foo.String()
    return nil
}

https://play.golang.org/p/BytXCeHMvt

您可以通过实现 json.Unmarshaler 界面

type test struct {
    Foo string `json:"foo"`
}

func (t *test) UnmarshalJSON(d []byte) error {
    tmp := struct {
        Foo interface{} `json:"foo"`
    }{}

    if err := json.Unmarshal(d, &tmp); err != nil {
        return err
    }

    switch v := tmp.Foo.(type) {
    case float64:
        t.Foo = strconv.Itoa(int(v))
    case string:
        t.Foo = v
    default:
        return fmt.Errorf("invalid value for Foo: %v", v)
    }

    return nil
}

https://play.golang.org/p/t0eI4wCxdB