为什么眼镜蛇不读我的配置文件

Question

眼镜蛇和毒蛇中的文档使我感到困惑。我做了 cobra init fooproject，然后在项目dir中进行了 cobra add bar。我有一个名为 foo的 PersistentFlag，这是 root命令的init函数。

func Execute() {
    if err := RootCmd.Execute(); err != nil {
        fmt.Println(err)
        os.Exit(-1)
    }
    fmt.Println(cfgFile)
    fmt.Println("fooString is: ", fooString)
}

func init() {
    cobra.OnInitialize(initConfig)
    // Here you will define your flags and configuration settings.
    // Cobra supports Persistent Flags, which, if defined here,
    // will be global for your application.
    RootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.fooproject.yaml)")
    RootCmd.PersistentFlags().StringVar(&fooString, "foo", "", "loaded from config")
    viper.BindPFlag("foo", RootCmd.PersistentFlags().Lookup("foo"))
    // Cobra also supports local flags, which will only run
    // when this action is called directly.
    RootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
}

我的配置文件看起来像这样...

---
foo: aFooString

，当我致电go run main.go时，我看到了...

A longer description that spans multiple lines and likely contains
examples and usage of using your application. For example:
Cobra is a CLI library for Go that empowers applications.
This application is a tool to generate the needed files
to quickly create a Cobra application.
Usage:
  fooproject [command]
Available Commands:
  bar         A brief description of your command
  help        Help about any command
Flags:
      --config string   config file (default is $HOME/.fooproject.yaml)
      --foo string      loaded from config
  -h, --help            help for fooproject
  -t, --toggle          Help message for toggle
Use "fooproject [command] --help" for more information about a command.
fooString is:

当我致电go run main.go bar时，我看到了...

Using config file: my/gopath/github.com/user/fooproject/.fooproject.yaml
bar called
fooString is:

因此，它正在使用配置文件，但似乎都没有读它。也许我误解了眼镜蛇和毒蛇的工作方式。有什么想法吗？

Answer 1

结合spf13/cobra和spf13/viper，首先将标志定义为COBRA：

RootCmd.PersistentFlags().StringP("foo", "", "loaded from config")

用Viper绑定它：

viper.BindPFlag("foo", RootCmd.PersistentFlags().Lookup("foo"))

并通过Viper的方法获取变量：

fmt.Println("fooString is: ", viper.GetString("foo"))

Answer 2

由于毒蛇值在某种程度上不如pflag(例如，对自定义数据类型不支持(，我对答案不满意，我不满意"使用Viper来检索值"，最终写了小帮手类型将值放回pflags中。

type viperPFlagBinding struct {
        configName string
        flagValue  pflag.Value
}
type viperPFlagHelper struct {
        bindings []viperPFlagBinding
}
func (vch *viperPFlagHelper) BindPFlag(configName string, flag *pflag.Flag) (err error) {
        err = viper.BindPFlag(configName, flag)
        if err == nil {
                vch.bindings = append(vch.bindings, viperPFlagBinding{configName, flag.Value})
        }
        return
}
func (vch *viperPFlagHelper) setPFlagsFromViper() {
        for _, v := range vch.bindings {
                v.flagValue.Set(viper.GetString(v.configName))
        }
}

func main() {
        var rootCmd = &cobra.Command{}
        var viperPFlagHelper viperPFlagHelper
        rootCmd.PersistentFlags().StringVar(&config.Password, "password", "", "API server password (remote HTTPS mode only)")
        viperPFlagHelper.BindPFlag("password", rootCmd.Flag("password"))
        rootCmd.PersistentPreRunE = func(cmd *cobra.Command, args []string) error {
                err := viper.ReadInConfig()
                if err != nil {
                        if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
                                return err
                        }
                }
                viperPFlagHelper.setPFlagsFromViper()
                return nil
        }
}

Answer 3

对于那些面临同一问题的人，问题在此呼叫上：

cobra.OnInitialize(initConfig)

函数initconfig不是直接执行的，而是附加到initializer的数组https://github.com/spf13/cobra/cobra/blob/master/master/cobra.go#l80

因此，执行Run字段时，将加载存储在您配置文件中的值：

  rootCmd = &cobra.Command{
    Use:   "example",
    Short: "example cmd",
    Run: func(cmd *cobra.Command, args []string) { // OnInitialize is called first
      fmt.Println(viper.AllKeys())
    },  
  }

Answer 4

@wgh的答案是正确的，您可以在rootcmd.persistenprerun中使用持久标志做某事，该标志将在所有其他sub命令中可用。

var rootCmd = &cobra.Command{
    PersistentPreRun: func(_ *cobra.Command, _ []string) {
        if persistentflag {
            // do something with persistentflag
        }
    },