Build go command line program tool chain

The story of laziness

Today's recommendation needs to start with a lazy story ：

Words , Not long ago , You need to output a cool... Sorted by release time Go List of recommended historical articles , Something like this

So , from GoCN The last one copy The title of the article ,5 Chapter down , Hands and eyes are out of tune , At this moment, I remembered that I seemed to be a yard farmer , This situation and this scene must coding a section , Let the code output this list .

The idea is simple , to glance at GoCN List of articles API, Let's look at the authentication method （ see header It's through cookie）, Then you can coding 了 , adopt API Pull article data , Extract the required fields and assemble them into MD The output is finished ！ When preparing a main.go When it's done , In line with the right coding The awe of , Simply think about the readability of the program 、 Expansibility , Decide whether to build a relatively complete command line program , as follows ：

Protagonist on stage

Then you need to implement the command line prompt in the above figure , Program parameter analysis, etc , Of course, it can be achieved without the help of third-party packages . but , Why don't the trees planted by our predecessors enjoy the cool , In the industry, there are mature implementations for the development of command line tools , Here is the main character of this article :

• cobra： Apply command line framework
• pflag： Command line parameter parsing
• viper： Profile parsing

Let's take a look at how to use these three big brothers to build Go Command line program .

Let's take a brief look at the project structure ：

.
├── cmd
│   ├── pull.go
│   └── root.go
├── config.yaml
├── file
│   └── cool-go.md
├── go.mod
├── go.sum
├── gocn-cli
└── main.go

Then introduce the three libraries recommended above :

go get -u github.com/spf13/[email protected]

go get -u github.com/spf13/viper

go get -u github.com/spf13/pflag

Coding

package cmd

import (
    "fmt"
    "github.com/spf13/cobra"
    "github.com/spf13/viper"
    "os"
)

var (
    cfgFile string
)

func init() {
    cobra.OnInitialize(initConfig)
    
    //  Parsing configuration file parameters 
    rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is ./config.yaml)")
}

// initConfig viper Load profile 
func initConfig() {
    if cfgFile != "" {
        viper.SetConfigFile(cfgFile)
    } else {
        viper.AddConfigPath(".")
        viper.SetConfigName("config")
    }
    
    if err := viper.ReadInConfig(); err != nil {
        fmt.Println("Can't read config file:", err)
        os.Exit(1)
    }
}

//  Create a global rootCmd
var rootCmd = &cobra.Command{
    Use:   "gocn-cli",
    Short: "gocn-cli is a command line tool for gocn.com",
    Long:  "gocn-cli is a command line tool for gocn.com",
    Run: func(cmd *cobra.Command, args []string) {
        
    },
}

// Execute  Carry out orders  main call 
func Execute() {
    if err := rootCmd.Execute(); err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
}

package cmd

import (
 "github.com/spf13/cobra"
 "github.com/spf13/viper"
 "os"
)

var (
 moduleName string
)

func init() {
    //  to rootCmd Add new orders pullCmd
 rootCmd.AddCommand(pullCmd)

 pullCmd.Flags().StringVarP(&moduleName, "module", "m", "", "module name")
}

var pullCmd = &cobra.Command{
 Use:   "pull gocn data",
 Short: "pull gocn data",
 Run: func(cmd *cobra.Command, args []string) {
  pullHandler()
 },
}

// pullHandler pullCmd  Corresponding processing function 
func pullHandler() {
 if moduleName == "" {
  fmt.Println("module name is required")
  os.Exit(1)
 }

 switch moduleName {
 case "cool-go":
  pullCoolGo()

 default:
  fmt.Println("module name is invalid")
  os.Exit(1)
 }
}

func pullCoolGo() {
 // TODO Write Your Code
}

Conclusion

The above briefly introduces how to use cobra、viper、pflag, Of course, there are many other uses for them , Here is a simple introduction .

so , A good command line program can be built through simple code .

Reference resources

• https://github.com/spf13/cobra

• https://github.com/spf13/viper

• https://github.com/spf13/pflag