Unmarshal()返回空结构 [英] Unmarshal() is returning empty structs

问题描述

我正在尝试从文件读取并将其加载到结构片中.我读入的行已正确加载，如块注释中所示.

I'm trying to read from a file and load it into a struct slice. The lines that I read in are loaded correct as shown in the block comment.

我遇到的问题是class变量不断返回空值.我在做什么错了?

The issue I'm having is that the class variable keeps coming back with empty values. What am I doing wrong?

func loadClasses(path string) []Class {
    var a []Class

    inFile, _ := os.Open(path)
    defer inFile.Close()
    scanner := bufio.NewScanner(inFile)
    scanner.Split(bufio.ScanLines)
    var class Class
    for scanner.Scan() {
        var err = json.Unmarshal(scanner.Bytes(), &class)

        if err != nil {
            fmt.Print("Error:", err)
        } else {
            a = append(a, class)
        }
    }
    return a
}

type Class struct {
    id   string
    name string
}

/*
Sample contents
"{"id":124997,"name":"Environmental Sciences"}
{"id":123905,"name":"Physical Education"}
{"id":127834,"name":"Mandarin"}
{"id":123507,"name":"Biology"}
{"id":123883,"name":"German"}
{"id":129148,"name":"German"}
{"id":123545,"name":"Spanish"}"

*/

感谢您的帮助.我的问题是两部分，结构成员必须大写，而我却错过了json: "id"和json: "name"

Thank you to isim for the help. My issue was two part, the struct members had to be capitalized and I was missing the json: "id" and json: "name"

推荐答案

您可以通过将字段的首字母更改为大写来导出Class结构中的字段，如下所示:

You can export the fields in your Class struct by changing the first letter of the fields to upper case like this:

type Class struct{
  Id string
  Name string
}

(可选)您还可以将标签添加到以下字段:

Optionally, you can also add tags to the fields like this:

type Class struct{
  Id string `json: "id"`
  Name string `json: "name"`
}

有关json包如何处理编码和解码的更多信息，可以在 json.Marshal 和 json.Unmarshal 文档.

More information on how the json package handles encoding and decoding can be found in the json.Marshal and json.Unmarshal docs respectively.

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