Question

我有一个接收JSON消息的应用。 JSON有各种各样的＆＃34;部分＆＃34; （以下示例）。每个部分都有一个名称，但除此之外的结构在每个部分完全不同。

我想要做的是仔细阅读各个部分，并将每个部分解组到适当的对象中。但奇怪的是我发现这很困难，因为看起来你可以将整个JSON解组成一个对象，或者你可以得到一个通用的map [string] interface {}。我发现的所有示例代码都进入了类型切换并手动分配变量......我希望将neato Unmarshal直接写入对象。

有没有办法为Unmarshal提供JSON的子集？我自己可以对字节[]进行切片和切块，但这看起来很可怕......当然其他人也经历过这样的事情？

这是我玩过的。

package main

import "encoding/json"

type Book struct {
    Author string
    Title  string
    Price  float64
}

type Movie struct {
    Title  string
    Year   float64
    Stars  float64
    Format string
}

var sections map[string]interface{}

func main() {

    /*
     * "Book" and "Movie" are "sections".
     * There are dozens of possible section types,
     * and which are present is not known ahead of time
     */

    incoming_msg_string := `
{
    "Book" : {
        "Author" : "Jack Kerouac",
        "Title" : "On the Road",
        "Price" : 5.99
    }, 
    "Movie" : {
        "Title" : "Sherlock Holmes vs. the Secret Weapon",
        "Year" : 1940,
        "Stars" : 2.5,
        "Format" : "DVD"
    }
}`

    /*
     * this code gets me a list of sections
     */

    var f interface{}
    err := json.Unmarshal([]byte(incoming_msg_string), &f)
    if err != nil {
        panic(err)
    }

    var list_of_sections []string
    for section_type, _ := range f.(map[string]interface{}) {
        list_of_sections = append(list_of_sections, section_type)
    }

    /*
       * next I would like to take the JSON in the "book" section
       * and unmarshal it into a Book object, then take the JSON
       * in the "movie" section and unmarshal it into a Movie object,
       * etc.
       *
       * https://blog.golang.org/json-and-go has an example on
       * decoding arbitrary data, but there's only one Unmarshaling.
       *
       * json.RawMessage has an example in the docs but it assumes
       * the objects are the same type (I think).  My attempts to use
       * it with a two-field struct (section name, and a raw message)
       * gave runtime errors.  Likewise unmarshaling into a 
       * []json.RawMessage gave "panic: json: cannot unmarshal object into Go value of type []json.RawMessage"
       *
       * What I'm looking for is something like:
       *   json.Unmarshal(some_json["a certain section"],&object)
       *
    */
}

任何面包屑痕迹都暗示非常感激。

Answer 1

对type Sections map[string]json.RawMessage变量进行初始解组。然后，您将获得与其关联的节类型和原始数据。您可以打开部分类型并解组到特定的部分结构，也可以解组为map [string] interface {}并一般地处理它们。（无论什么最适合您的应用。）

在golang

1 个答案: