👨💻簡介
今天來介紹一個自己開發後端蠻常用的一個 package，promptui，拿來做menu真的很方便，promptui有兩個主要的輸入模式：
- Prompt：跳出單行使用者輸入。
- Select：提供一個選項列表供使用者選擇。
Prompt
prompt是一個struct，當執行Run時會返回輸入的結果type Prompt struct {
// Label is the value displayed on the command line prompt.
//
// The value for Label can be a simple string or a struct that will need to be accessed by dot notation
// inside the templates. For example, `{{ .Name }}` will display the name property of a struct.
Label interface{}
// Default is the initial value for the prompt. This value will be displayed next to the prompt's label
// and the user will be able to view or change it depending on the options.
Default string
// AllowEdit lets the user edit the default value. If false, any key press
// other than <Enter> automatically clears the default value.
AllowEdit bool
// Validate is an optional function that fill be used against the entered value in the prompt to validate it.
Validate ValidateFunc
// Mask is an optional rune that sets which character to display instead of the entered characters. This
// allows hiding private information like passwords.
Mask rune
// HideEntered sets whether to hide the text after the user has pressed enter.
HideEntered bool
// Templates can be used to customize the prompt output. If nil is passed, the
// default templates are used. See the PromptTemplates docs for more info.
Templates *PromptTemplates
// IsConfirm makes the prompt ask for a yes or no ([Y/N]) question rather than request an input. When set,
// most properties related to input will be ignored.
IsConfirm bool
// IsVimMode enables vi-like movements (hjkl) and editing.
IsVimMode bool
// the Pointer defines how to render the cursor.
Pointer Pointer
Stdin io.ReadCloser
Stdout io.WriteCloser
}
語法如下：
func (*promptui.Prompt).Run() (string, error)
package main
import (
"fmt"
"github.com/manifoldco/promptui"
)
func main() {
prompt := promptui.Prompt{
Label: "Anything",
}
result, err := prompt.Run()
if err != nil {
fmt.Printf("Prompt failed %v\n", err)
return
}
fmt.Printf("You typed %q\n", result)
}
確認（Confirm）
建立一個確認提示，使用者可以選擇是或否。
package main
import (
"fmt"
"github.com/manifoldco/promptui"
)
func main() {
prompt := promptui.Prompt{
Label: "Delete all resources",
IsConfirm: true,
}
_, err := prompt.Run()
if err != nil {
fmt.Printf("Prompt failed %v\n", err)
return
}
fmt.Printf("Resources deleted")
}
自定義提示（Custom Prompt）
這個功能是讓使用者可以自己定義提示的外觀和行為。例如，你可以更改提示的顏色，標籤和其他設定。
package main
import (
"fmt"
"errors"
"github.com/manifoldco/promptui"
)
func main() {
prompt := promptui.Prompt{
Label: "Enter your name",
Validate: func(input string) error {
if len(input) < 3 {
return errors.New("Name must have more than 3 characters")
}
return nil
},
}
result, err := prompt.Run()
if err != nil {
fmt.Printf("Prompt failed %v\n", err)
return
}
fmt.Printf("Hello %q\n", result)
}
提示預設值（Prompt Default）
Promptui 支援設定提示的預設值。
package main
import (
"fmt"
"github.com/manifoldco/promptui"
)
func main() {
prompt := promptui.Prompt{
Label: "Enter your name",
Default: "Alan",
}
result, err := prompt.Run()
if err != nil {
fmt.Printf("Prompt failed %v\n", err)
return
}
fmt.Printf("Hello %q\n", result)
}
密碼提示（Password Prompt）
Promptui 可以用來建立一個密碼提示，其中使用者輸入的文本將被掩蓋。
package main
import (
"fmt"
"github.com/manifoldco/promptui"
)
func main() {
prompt := promptui.Prompt{
Label: "Enter Password",
Mask: '*',
}
result, err := prompt.Run()
if err != nil {
fmt.Printf("Prompt failed %v\n", err)
return
}
fmt.Printf("Password entered: %q\n", result)
}
Select
Select也是一個struct，與Prompt不同的是當執行Run時會返回index以及選中的結果
type Select struct {
// Label is the text displayed on top of the list to direct input. The IconInitial value "?" will be
// appended automatically to the label so it does not need to be added.
//
// The value for Label can be a simple string or a struct that will need to be accessed by dot notation
// inside the templates. For example, `{{ .Name }}` will display the name property of a struct.
Label interface{}
// Items are the items to display inside the list. It expect a slice of any kind of values, including strings.
//
// If using a slice of strings, promptui will use those strings directly into its base templates or the
// provided templates. If using any other type in the slice, it will attempt to transform it into a string
// before giving it to its templates. Custom templates will override this behavior if using the dot notation
// inside the templates.
//
// For example, `{{ .Name }}` will display the name property of a struct.
Items interface{}
// Size is the number of items that should appear on the select before scrolling is necessary. Defaults to 5.
Size int
// CursorPos is the initial position of the cursor.
CursorPos int
// IsVimMode sets whether to use vim mode when using readline in the command prompt. Look at
// https://godoc.org/github.com/chzyer/readline#Config for more information on readline.
IsVimMode bool
// HideHelp sets whether to hide help information.
HideHelp bool
// HideSelected sets whether to hide the text displayed after an item is successfully selected.
HideSelected bool
// Templates can be used to customize the select output. If nil is passed, the
// default templates are used. See the SelectTemplates docs for more info.
Templates *SelectTemplates
// Keys is the set of keys used in select mode to control the command line interface. See the SelectKeys docs for
// more info.
Keys *SelectKeys
// Searcher is a function that can be implemented to refine the base searching algorithm in selects.
//
// Search is a function that will receive the searched term and the item's index and should return a boolean
// for whether or not the terms are alike. It is unimplemented by default and search will not work unless
// it is implemented.
Searcher list.Searcher
// StartInSearchMode sets whether or not the select mode should start in search mode or selection mode.
// For search mode to work, the Search property must be implemented.
StartInSearchMode bool
list *list.List
// A function that determines how to render the cursor
Pointer Pointer
Stdin io.ReadCloser
Stdout io.WriteCloser
}
語法如下：
func (*promptui.Select).Run() (int, string, error)
func (*promptui.Select).RunCursorAt(cursorPos int, scroll int) (int, string, error)
func (*promptui.Select).ScrollPosition() int
package main
import (
"fmt"
"github.com/manifoldco/promptui"
)
func main() {
prompt := promptui.Select{
Label: "Select Day",
Items: []string{"Monday", "Tuesday", "Wednesday", "Thursday", "Friday",
"Saturday", "Sunday"},
}
_, result, err := prompt.Run()
if err != nil {
fmt.Printf("Prompt failed %v\n", err)
return
}
fmt.Printf("You choose %q\n", result)
}
自定義選擇（Custom Select）
除了基本的選擇提示外，Promptui 還允許使用者自定義選擇列表的外觀和行為。
package main
import (
"fmt"
"github.com/manifoldco/promptui"
)
func main() {
prompt := promptui.Select{
Label: "Choose Color",
Items: []string{"Red", "Blue", "Green"},
Templates: &promptui.SelectTemplates{
Label: "{{ . }}?",
Active: "\U0001F336 {{ . | red }}",
Inactive: " {{ . | cyan }}",
Selected: "\U0001F336 {{ . | red | cyan }}",
},
}
_, result, err := prompt.Run()
if err != nil {
fmt.Printf("Prompt failed %v\n", err)
return
}
fmt.Printf("You choose %q\n", result)
}
選擇添加（Select Add）
Promptui 還允許使用者在選擇提示中添加新的選項。
package main
import (
"fmt"
"github.com/manifoldco/promptui"
)
func main() {
items := []string{"Monday", "Tuesday", "Wednesday", "Thursday", "Friday"}
prompt := promptui.SelectWithAdd{
Label: "What day is it?",
Items: items,
AddLabel: "Other",
}
idx, result, err := prompt.Run()
if err != nil {
fmt.Printf("Prompt failed %v\n", err)
return
}
if idx == len(items) {
fmt.Printf("You chose to add %q\n", result)
} else {
fmt.Printf("You chose %q\n", result)
}
}
