定义 JSON 对象的结构

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我有一个来自 api 的 json 响应对象，如下所示：

[
    {
        "peoples": {
            "1": {"name": "Jhon", "age": 123},
            "2": {"name": "Jhon", "age": 123},
            "3": {"name": "Jhon", "age": 123},
            "4": {"name": "Jhon", "age": 123},
            "_object": true,
            "_timestamp": "2020-08-05T07:05:55.509Z",
            "_writable": false
        }
    }
]

参数：peoples、_object、_timestamp 和 _writable 是固定的。动态值为 1,2,3,4...n 参数。

该结构中 peoples 的数量可以超过 4 个或可以是 1。有任何优雅的解决方案来创建一个 struct 对象或 json.unmarshal 吗？

解决方案

借用 the input example from Sarath Sadasivan Pillai（请参阅 comment）、here (link to Playground example) 是一种使用 map[string]json.rawmessage 和自定义解组函数来实现此目的的方法：

package main

import (
    "encoding/json"
    "fmt"
    "strconv"
    "time"
)

type Person struct {
    Name string `json:"name"`
    Age  int    `json:"age"`
}

type Keywords struct {
    Object    bool      `json:"_object"`
    Timestamp time.Time `json:"_timestamp"`
    Writable  bool      `json:"_writable"`
}

type Decoded struct {
    People map[string]Person // or perhaps just []Person
    Info   Keywords
}

var input []byte = []byte(`{
        "1": {"name": "Jhon", "age": 123},
        "2": {"name": "Jhon", "age": 123},
        "3": {"name": "Jhon", "age": 123},
        "4": {"name": "Jhon", "age": 123},
        "_object": true,
        "_timestamp": "2020-08-05T07:05:55.509Z",
        "_writable": false
}`)

// Unmarshal json in the input format outlined by
// the example above: a map of numeric strings to Name/Age pair,
// plus some keywords.

func (d *Decoded) UnmarshalJSON(data []byte) error {
    if err := json.Unmarshal(data, &d.Info); err != nil {
        return err
    }
    var m map[string]json.RawMessage
    if err := json.Unmarshal(data, &m); err != nil {
        return err
    }
    if d.People == nil {
        d.People = make(map[string]Person)
    }
    for k := range m {
        // This is the hard part: you must choose how
        // to decide whether to decode this as a Person.
        // Here, we use strconv.Atoi() as in the example
        // by Sarath Sadasivan Pillai, but there are as
        // many options as you can think of.
        //
        // For instance, another method would be to try
        // decoding the json.RawMessage as a Person.  It's
        // also not clear whether the numeric values imply
        // some particular ordering, which maps discard.
        // (If these come out in order, that's just luck.)
        if _, err := strconv.Atoi(k); err != nil {
            continue
        }
        var p Person
        if err := json.Unmarshal(m[k], &p); err != nil {
            return err
        }
        d.People[k] = p
    }
    return nil
}

func main() {
    var x Decoded
    err := json.Unmarshal(input, &x)
    if err != nil {
        fmt.Printf("failed: %v\n", err)
    } else {
        fmt.Printf("succeeded:\n%#v\n", x.Info)
        for k := range x.People {
            fmt.Printf("person %q = %#v\n", k, x.People[k])
        }
    }
}

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