gjson can not only flexibly parse and retrieve unknown data structure content but also dynamically create and modify data structure content.

Dynamic Creation

Example 1, Simple Usage

func main() {
    j := gjson.New(nil)
    j.Set("name", "John")
    j.Set("score", 99.5)
    fmt.Printf(
        "Name: %s, Score: %v\n",
        j.Get("name").String(),
        j.Get("score").Float32(),
    )
    fmt.Println(j.MustToJsonString())
    // Output:
    // Name: John, Score: 99.5
    // {"name":"John","score":99.5}
}

Example 2, Creating Arrays

func main() {
    j := gjson.New(nil)
    for i := 0; i < 5; i++ {
        j.Set(fmt.Sprintf(`%d.id`, i), i)
        j.Set(fmt.Sprintf(`%d.name`, i), fmt.Sprintf(`student-%d`, i))
    }
    fmt.Println(j.MustToJsonString())
    // Output:
    // [{"id":0,"name":"student-0"},{"id":1,"name":"student-1"},{"id":2,"name":"student-2"},{"id":3,"name":"student-3"},{"id":4,"name":"student-4"}]
}

Dynamic Modification

func main() {
    data :=
        `{
    "users" : {
        "count" : 2,
        "list"  : [
            {"name" : "Ming", "score" : 60},
            {"name" : "John", "score" : 59}
        ]
    }
}`
    if j, err := gjson.DecodeToJson(data); err != nil {
        panic(err)
    } else {
        j.Set("users.list.1.score", 100)
        fmt.Println("John Score:", j.Get("users.list.1.score").Float32())
        fmt.Println(j.MustToJsonString())
    }
    // Output:
    // John Score: 100
    // {"users":{"count":2,"list":[{"name":"Ming","score":60},{"name":"John","score":100}]}}
}

JSON data can be read through gjson, and the internal variables can be changed using the Set method. Of course, you can also add/delete content. When you need to delete content, just set the value to nil. The runtime modification features of the gjson package are very powerful, and with the support of this feature, the encoding/decoding of various data structures becomes extremely flexible and convenient.