cobra-practise

Getting Started

https://github.com/spf13/cobra

https://www.youtube.com/watch?v=7U12a-TTtfo doc https://godoc.org/github.com/spf13/cobra#Command

concepts

cobra is a powerful library to build modern cli applications. it's embedded with pflag and have a powerful combination with viper

convention

• appName/
  • cmd/
    • root.go
    • something.go
  • main.go

hands on staff

command var follow the structure from the cobra.Commands flags can be persistent or local.we can bind a command to another command as a sub command. flags can be useful can make custom validator

var (
    persistentFlag bool
    localFlag      bool
    times          int
    echoFlag       bool
    // version        bool

    rootCmd = &cobra.Command{
        Use:   "CLI",
        Short: "a example of cobra",
        Long: `cobra is used to develop cli base application.
                which was developed by spf13`,
        Version: "v1.0",
        Run: func(cmd *cobra.Command, args []string) {
            fmt.Println("hello from the root command", persistentFlag)
            cmd.SetVersionTemplate("v1.1")

            // fmt.Println("v3.o")
        },
    }

    echoCmd = &cobra.Command{
        Use:   "echo [string to echo]",
        Short: "prints given string to stdout",
        Args:  cobra.MinimumNArgs(1),
        Run: func(cmd *cobra.Command, args []string) {
            if persistentFlag {
                fmt.Println("persistent echo")
            }
            fmt.Println("> : " + strings.Join(args, " "))
        },
    }

    timesCmd = &cobra.Command{
        Use:   "times [string to echo]",
        Short: "number of time you want to execute a command",
        Args:  cobra.MinimumNArgs(1),
        RunE: func(cmd *cobra.Command, args []string) error {
            if times == 0 {
                return errors.New("times cant be zero")
            }
            for i := 0; i < times; i++ {
                fmt.Println("> : " + strings.Join(args, " "))
            }
            return nil
        },
    }
)

func init() {

    rootCmd.PersistentFlags().BoolVarP(&persistentFlag, "persist", "p", false, "a persistent flag")
    rootCmd.Flags().BoolVarP(&localFlag, "local-flag", "l", false, "a local flag")
    // rootCmd.PersistentFlags().BoolVarP(&version, "version", "v", false, "prints the version")
    echoCmd.PersistentFlags().BoolVarP(&echoFlag, "echoFlag", "e", false, "echo persistent flag")
    timesCmd.Flags().IntVarP(&times, "times", "t", 1, "number of times")

    rootCmd.AddCommand(echoCmd)
    echoCmd.AddCommand(timesCmd)
}

//Execute executes the root command
func Execute() error {
    return rootCmd.Execute()
}