Added cobra example for cli tooling.

Author: William Kennedy

courses/hardcorego/tooling/README.md

@@ -12,5 +12,8 @@ This is a class for any intermediate-level developer who has some experience wit
 [Memory Trace](../../../topics/memory_trace/README.md) | 
 [Scheduler Trace](../../../topics/sched_trace/README.md) | 
 [Stack Traces](../../../topics/stack_trace/README.md)
+
+#### Command Line Interfaces
+[Cobra](../../../topics/cli/cobra/README.md)
 ___
 All material is licensed under the [Apache License Version 2.0, January 2004](http://www.apache.org/licenses/LICENSE-2.0).

topics/cli/TODO

@@ -0,0 +1,44 @@
+## Cobra
+
+Cobra is both a library for creating powerful modern CLI applications as well as a program to generate applications and command files. Cobra is also an application that will generate your application scaffolding to rapidly develop a Cobra-based application.
+
+## Notes
+
+* Easy subcommand-based CLIs: app server, app fetch, etc.
+* Fully POSIX-compliant flags (including short & long versions)
+* Nested subcommands
+* Global, local and cascading flags
+* Easy generation of applications & commands with cobra create appname & cobra add cmdname
+* Intelligent suggestions (app srver... did you mean app server?)
+* Automatic help generation for commands and flags
+* Automatic detailed help for app help [command]
+* Automatic help flag recognition of -h, --help, etc.
+* Automatically generated bash autocomplete for your application
+* Automatically generated man pages for your application
+* Command aliases so you can change things without breaking them
+* The flexibilty to define your own help, usage, etc.
+* Optional tight integration with viper for 12-factor apps
+
+## Links
+
+https://github.com/spf13/cobra
+
+http://spf13.com/post/announcing-cobra/
+
+## Code Review
+
+[main](main.go)
+
+[commands](cmduser/commands.go)
+
+[create command](cmduser/create.go)
+
+## Exercises
+
+### Exercise 1
+
+Add a new user command called get to retrieve a user record by email. For now reuse the User type and create a value and return some fake data. Then display the user value in the terminal. The purpose of the exercise it to wire up a new command. Use the create command as your template.
+
+[Answer](exercises/exercise1/exercise1.go)
+___
+All material is licensed under the [Apache License Version 2.0, January 2004](http://www.apache.org/licenses/LICENSE-2.0).

topics/cli/cobra/README.md

@@ -0,0 +1,17 @@
+package cmduser
+
+import "github.com/spf13/cobra"
+
+// userCmd represents the parent for all user cli commands.
+var userCmd = &cobra.Command{
+	Use:   "user",
+	Short: "user provides a shelf CLI for managing user records.",
+}
+
+// GetCommands returns the user commands.
+func GetCommands() *cobra.Command {
+	// TODO: Add all the commands here.
+	addCreate()
+
+	return userCmd
+}

topics/cli/cobra/cmduser/commands.go

@@ -0,0 +1,80 @@
+package cmduser
+
+import (
+	"errors"
+
+	"github.com/spf13/cobra"
+)
+
+var createLong = `Use create to add a new user to the system. The user email
+must be unique for every user.
+
+Example:
+  ./shelf user create -n "Bill Kennedy" -e "[email protected]" -p "yefc*7fdf92"
+`
+
+// create contains the state for this command.
+var create struct {
+	name  string
+	pass  string
+	email string
+}
+
+// addCreate handles the creation of users.
+func addCreate() {
+	cmd := &cobra.Command{
+		Use:   "create",
+		Short: "Add a new user to the system.",
+		Long:  createLong,
+		Run:   runCreate,
+	}
+
+	cmd.Flags().StringVarP(&create.name, "name", "n", "", "Full name for the user.")
+	cmd.Flags().StringVarP(&create.email, "email", "e", "", "Email for the user.")
+	cmd.Flags().StringVarP(&create.pass, "pass", "p", "", "Password for the user.")
+
+	userCmd.AddCommand(cmd)
+}
+
+// runCreate is the code that implements the create command.
+func runCreate(cmd *cobra.Command, args []string) {
+	cmd.Printf("Creating User : Name[%s] Email[%s] Pass[%s]\n", create.name, create.email, create.pass)
+
+	if create.name == "" && create.email == "" && create.pass == "" {
+		cmd.Help()
+		return
+	}
+
+	u := User{
+		Status:   1,
+		Name:     "Bill",
+		Email:    "[email protected]",
+		Password: "my passoword",
+	}
+
+	if err := createUser(&u); err != nil {
+		cmd.Println("Creating User : ", err)
+		return
+	}
+
+	cmd.Println("Creating User : Created")
+}
+
+//==============================================================================
+
+// User represents a sample user model.
+type User struct {
+	Status   int
+	Name     string
+	Email    string
+	Password string
+}
+
+// createUser is a sample function to simulate a user creation.
+func createUser(u *User) error {
+	if u.Status == 0 {
+		return errors.New("Invalid user value")
+	}
+
+	return nil
+}

topics/cli/cobra/cmduser/create.go

@@ -0,0 +1,80 @@
+package cmduser
+
+import (
+	"encoding/json"
+
+	"github.com/spf13/cobra"
+)
+
+var getLong = `Use get to retrieve a user from the system.
+
+Example:
+  ./shelf user get -e "[email protected]"
+`
+
+// get contains the state for this command.
+var get struct {
+	email string
+}
+
+// addCreate handles the creation of users.
+func addCreate() {
+	cmd := &cobra.Command{
+		Use:   "get",
+		Short: "Get retrieve a user from the system.",
+		Long:  getLong,
+		Run:   runGet,
+	}
+
+	cmd.Flags().StringVarP(&get.email, "email", "e", "", "Email for the user.")
+
+	// THIS WILL BE AVAILABLE WHEN IN THE SAME PACKAGE.
+	//userCmd.AddCommand(cmd)
+}
+
+// runGet is the code that implements the create command.
+func runGet(cmd *cobra.Command, args []string) {
+	cmd.Printf("Getting User : Email[%s]\n", get.email)
+
+	if get.email == "" {
+		cmd.Help()
+		return
+	}
+
+	u, err := getUser(get.email)
+	if err != nil {
+		cmd.Println("Getting User : ", err)
+		return
+	}
+
+	data, err := json.MarshalIndent(&u, "", "    ")
+	if err != nil {
+		cmd.Println("Getting User : ", err)
+		return
+	}
+
+	cmd.Printf("\n%s\n\n", string(data))
+}
+
+//==============================================================================
+
+// User represents a sample user model.
+// NEED THIS FOR THE EXERCISE TO BUILD.
+type User struct {
+	Status   int
+	Name     string
+	Email    string
+	Password string
+}
+
+// createUser is a sample function to simulate a user creation.
+func getUser(email string) (*User, error) {
+	u := User{
+		Status:   1,
+		Name:     "Bill",
+		Email:    "[email protected]",
+		Password: "my passoword",
+	}
+
+	return &u, nil
+}

topics/cli/cobra/exercises/exercise1/exercise1.go

@@ -0,0 +1,21 @@
+// This program provides a sample building cli tooling.
+package main
+
+import (
+	"github.com/ardanlabs/gotraining/topics/cli/cobra/cmduser"
+
+	"github.com/spf13/cobra"
+)
+
+var shelf = &cobra.Command{
+	Use:   "binary",
+	Short: "binary provides what...",
+}
+
+func main() {
+	// TODO: Add more commands here.
+	shelf.AddCommand(cmduser.GetCommands())
+
+	// Execute the program and process the flags.
+	shelf.Execute()
+}