docs(examples): filepicker AllowedTypes example (#713)

examples/file-picker/main.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"strings"
+	"time"
 
 	"github.com/charmbracelet/bubbles/filepicker"
 	tea "github.com/charmbracelet/bubbletea"
@@ -13,6 +15,15 @@ type model struct {
 	filepicker   filepicker.Model
 	selectedFile string
 	quitting     bool
+	err          error
+}
+
+type clearErrorMsg struct{}
+
+func clearErrorAfter(t time.Duration) tea.Cmd {
+	return tea.Tick(t, func(_ time.Time) tea.Msg {
+		return clearErrorMsg{}
+	})
 }
 
 func (m model) Init() tea.Cmd {
@@ -27,6 +38,8 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			m.quitting = true
 			return m, tea.Quit
 		}
+	case clearErrorMsg:
+		m.err = nil
 	}
 
 	var cmd tea.Cmd
@@ -38,6 +51,15 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.selectedFile = path
 	}
 
+	// Did the user select a disabled file?
+	// This is only necessary to display an error to the user.
+	if didSelect, path := m.filepicker.DidSelectDisabledFile(msg); didSelect {
+		// Let's clear the selectedFile and display an error.
+		m.err = errors.New(path + " is not valid.")
+		m.selectedFile = ""
+		return m, tea.Batch(cmd, clearErrorAfter(2*time.Second))
+	}
+
 	return m, cmd
 }
 
@@ -47,7 +69,9 @@ func (m model) View() string {
 	}
 	var s strings.Builder
 	s.WriteString("\n  ")
-	if m.selectedFile == "" {
+	if m.err != nil {
+		s.WriteString(m.filepicker.Styles.DisabledFile.Render(m.err.Error()))
+	} else if m.selectedFile == "" {
 		s.WriteString("Pick a file:")
 	} else {
 		s.WriteString("Selected file: " + m.filepicker.Styles.Selected.Render(m.selectedFile))
@@ -58,6 +82,7 @@ func (m model) View() string {
 
 func main() {
 	fp := filepicker.New()
+	fp.AllowedTypes = []string{".mod", ".sum", ".go", ".txt", ".md"}
 	fp.CurrentDirectory, _ = os.UserHomeDir()
 
 	m := model{