如何在 Golang 中使用动态键解析 YAML

Posted 2023-02-26

【中文标题】如何在 Golang 中使用动态键解析 YAML

【英文标题】：How to parse YAML with dynamic key in Golang

【发布时间】：2015-11-15 19:29:25

【问题描述】：

我正在尝试使用 Go 解析 YAML 文件。问题是 YAML 文件中的键可能并不总是相同的。这是为了进行 API 版本控制，以便用户可以定义他们支持的版本。例如 V1、V2、V3 等。它们不需要按顺序排列，可以省略它们不支持的版本，即 V0、V2、V5 等。

package main

import (
  "fmt"
  "gopkg.in/yaml.v2"
)

var data = `
---
development:
  skip-header-validation: true
  V1:
    current: "1.0.0"
    mime_types:
      - application/vnd.company.jk.identity+json;
      - application/vnd.company.jk.user+json;
      - application/vnd.company.jk.role+json;
      - application/vnd.company.jk.scope+json;
      - application/vnd.company.jk.test+json;
    skip-mime-type-validation: true
    skip-version-validation: true
  V2:
    current: "2.0.0"
    mime_types:
      - application/vnd.company.jk.identity+json;
      - application/vnd.company.jk.user+json;
      - application/vnd.company.jk.role+json;
      - application/vnd.company.jk.scope+json;
      - application/vnd.company.jk.test+json;

`

type MajorVersion struct 
  Current                 string    `yaml:"current"`
  MimeTypes               []string  `yaml:"mime_types"`
  SkipVersionValidation   bool      `yaml:"skip-version-validation"`
  SkipMimeTypeValidation  bool      `yaml:"skip-mime-type-validation"`


type Environment struct 
  SkipHeaderValidation  bool        `yaml:"skip-header-validation"`
  Version               map[string]MajorVersion


func main() 
  e := Environment

  yaml.Unmarshal([]byte(data), &e)
  fmt.Println(e)

我看到了similar question asked here

这是在顶层，我还没有完全弄清楚如何从结构内部做到这一点。

【参考方案1】：

首先，您尝试将根解析为Environment，但它的实际类型是map[string]Environment。其次，如果您想保留该类型结构，您将需要一个自定义的Unmarshaler。像这样的：

package main

import (
    "fmt"

    "gopkg.in/yaml.v2"
)

var data = `
---
development:
  skip-header-validation: true
  V1:
    current: "1.0.0"
    mime_types:
      - application/vnd.company.jk.identity+json;
      - application/vnd.company.jk.user+json;
      - application/vnd.company.jk.role+json;
      - application/vnd.company.jk.scope+json;
      - application/vnd.company.jk.test+json;
    skip-mime-type-validation: true
    skip-version-validation: true
  V2:
    current: "2.0.0"
    mime_types:
      - application/vnd.company.jk.identity+json;
      - application/vnd.company.jk.user+json;
      - application/vnd.company.jk.role+json;
      - application/vnd.company.jk.scope+json;
      - application/vnd.company.jk.test+json;

`

type MajorVersion struct 
    Current                string   `yaml:"current"`
    MimeTypes              []string `yaml:"mime_types"`
    SkipVersionValidation  bool     `yaml:"skip-version-validation"`
    SkipMimeTypeValidation bool     `yaml:"skip-mime-type-validation"`


type Environment struct 
    SkipHeaderValidation bool
    Versions             map[string]MajorVersion


func (e *Environment) UnmarshalYAML(unmarshal func(interface) error) error 
    var params struct 
        SkipHeaderValidation bool `yaml:"skip-header-validation"`
    
    if err := unmarshal(&params); err != nil 
        return err
    
    var versions map[string]MajorVersion
    if err := unmarshal(&versions); err != nil 
        // Here we expect an error because a boolean cannot be converted to a
        // a MajorVersion
        if _, ok := err.(*yaml.TypeError); !ok 
            return err
        
    
    e.SkipHeaderValidation = params.SkipHeaderValidation
    e.Versions = versions
    return nil


func main() 
    var e map[string]Environment
    if err := yaml.Unmarshal([]byte(data), &e); err != nil 
        fmt.Println(err.Error())
    
    fmt.Printf("%#v\n", e)

输出（使用makeup后）：

map[string]main.Environment
    "development": 
        SkipHeaderValidation: true,
        Versions:             
            "V2": 
                Current:                "2.0.0",
                MimeTypes:              "application/vnd.company.jk.identity+json;", "application/vnd.company.jk.user+json;", "application/vnd.company.jk.role+json;", "application/vnd.company.jk.scope+json;", "application/vnd.company.jk.test+json;",
                SkipVersionValidation:  false,
                SkipMimeTypeValidation: false,
            ,
            "V1": 
                Current:                "1.0.0",
                MimeTypes:              "application/vnd.company.jk.identity+json;", "application/vnd.company.jk.user+json;", "application/vnd.company.jk.role+json;", "application/vnd.company.jk.scope+json;", "application/vnd.company.jk.test+json;",
                SkipVersionValidation:  true,
                SkipMimeTypeValidation: true,
            ,
        ,
    ,

【讨论】：

哇，好人，谢谢。很酷，看看这是如何在 go 中完成的。有趣的是，有时您需要多少代码来解析 yaml！