Merge pull request #5123 from jimorc/issue2836

Add string binding to the Selected field of the Select widget

widget/select.go

@@ -1,10 +1,12 @@
 package widget
 
 import (
+	"fmt"
 	"image/color"
 
 	"fyne.io/fyne/v2"
 	"fyne.io/fyne/v2/canvas"
+	"fyne.io/fyne/v2/data/binding"
 	"fyne.io/fyne/v2/driver/desktop"
 	"fyne.io/fyne/v2/theme"
 )
@@ -24,6 +26,8 @@ type Select struct {
 	PlaceHolder string
 	OnChanged   func(string) `json:"-"`
 
+	binder basicBinder
+
 	focused bool
 	hovered bool
 	popUp   *PopUpMenu
@@ -47,6 +51,30 @@ func NewSelect(options []string, changed func(string)) *Select {
 	return s
 }
 
+// NewSelectWithData returns a new select widget connected to the specified data source.
+//
+// Since: 2.6
+func NewSelectWithData(options []string, data binding.String) *Select {
+	sel := NewSelect(options, nil)
+	sel.Bind(data)
+
+	return sel
+}
+
+// Bind connects the specified data source to this select.
+// The current value will be displayed and any changes in the data will cause the widget
+// to update.
+//
+// Since: 2.6
+func (s *Select) Bind(data binding.String) {
+	s.binder.SetCallback(s.updateFromData)
+	s.binder.Bind(data)
+
+	s.OnChanged = func(_ string) {
+		s.binder.CallWithData(s.writeData)
+	}
+}
+
 // ClearSelected clears the current option of the select widget.  After
 // clearing the current option, the Select widget's PlaceHolder will
 // be displayed.
@@ -239,6 +267,15 @@ func (s *Select) TypedRune(_ rune) {
 	// intentionally left blank
 }
 
+// Unbind disconnects any configured data source from this Select.
+// The current value will remain at the last value of the data source.
+//
+// Since: 2.6
+func (s *Select) Unbind() {
+	s.OnChanged = nil
+	s.binder.Unbind()
+}
+
 func (s *Select) popUpPos() fyne.Position {
 	buttonPos := fyne.CurrentApp().Driver().AbsolutePositionForObject(s.super())
 	return buttonPos.Add(fyne.NewPos(0, s.Size().Height-s.Theme().Size(theme.SizeNameInputBorder)))
@@ -279,6 +316,23 @@ func (s *Select) tapAnimation() {
 	}
 }
 
+func (s *Select) updateFromData(data binding.DataItem) {
+	if data == nil {
+		return
+	}
+	stringSource, ok := data.(binding.String)
+	if !ok {
+		return
+	}
+
+	val, err := stringSource.Get()
+	if err != nil {
+		return
+	}
+	s.SetSelected(val)
+
+}
+
 func (s *Select) updateSelected(text string) {
 	s.Selected = text
 
@@ -289,6 +343,26 @@ func (s *Select) updateSelected(text string) {
 	s.Refresh()
 }
 
+func (s *Select) writeData(data binding.DataItem) {
+	if data == nil {
+		return
+	}
+	stringTarget, ok := data.(binding.String)
+	if !ok {
+		return
+	}
+	currentValue, err := stringTarget.Get()
+	if err != nil {
+		return
+	}
+	if currentValue != s.Selected {
+		err := stringTarget.Set(s.Selected)
+		if err != nil {
+			fyne.LogError(fmt.Sprintf("Failed to set binding value to %s", s.Selected), err)
+		}
+	}
+}
+
 type selectRenderer struct {
 	icon       *Icon
 	label      *RichText

widget/select_test.go

@@ -8,6 +8,7 @@ import (
 
 	"fyne.io/fyne/v2"
 	"fyne.io/fyne/v2/canvas"
+	"fyne.io/fyne/v2/data/binding"
 	"fyne.io/fyne/v2/internal/cache"
 	"fyne.io/fyne/v2/layout"
 	"fyne.io/fyne/v2/test"
@@ -25,6 +26,19 @@ func TestNewSelect(t *testing.T) {
 	assert.Equal(t, "", combo.Selected)
 }
 
+func TestNewSelectWithData(t *testing.T) {
+	data := binding.NewString()
+	combo := widget.NewSelectWithData([]string{"1", "2", "3"}, data)
+
+	assert.Equal(t, 3, len(combo.Options))
+	assert.Equal(t, "", combo.Selected)
+
+	err := data.Set("2")
+	assert.Nil(t, err)
+	waitForBinding()
+	assert.Equal(t, "2", combo.Selected)
+}
+
 func TestSelect_Align(t *testing.T) {
 	test.NewTempApp(t)
 
@@ -43,6 +57,52 @@ func TestSelect_Align(t *testing.T) {
 	assertRendersToPlatformMarkup(t, "select/%s/trailing.xml", c)
 }
 
+func TestSelect_Options(t *testing.T) {
+	s := widget.NewSelect([]string{"1", "2", "3"}, nil)
+	s.SetSelected("2")
+	assert.Equal(t, "2", s.Selected)
+
+	s.SetOptions([]string{"4", "5"})
+	assert.Equal(t, "2", s.Selected)
+	s.Selected = ""
+	assert.Equal(t, "", s.Selected)
+}
+
+func TestSelect_Binding(t *testing.T) {
+	s := widget.NewSelect([]string{"1", "2", "3"}, nil)
+	s.SetSelected("2")
+	assert.Equal(t, "2", s.Selected)
+	waitForBinding() // this time it is the de-echo before binding
+
+	str := binding.NewString()
+	s.Bind(str)
+	waitForBinding()
+	value, err := str.Get()
+	assert.Nil(t, err)
+	assert.Equal(t, "", value)
+	assert.Equal(t, "2", s.Selected) // no match to options, so keep previous value
+
+	err = str.Set("3")
+	assert.Nil(t, err)
+	waitForBinding()
+	assert.Equal(t, "3", s.Selected)
+
+	s.Unbind()
+	assert.Nil(t, s.OnChanged)
+	err = str.Set("1")
+	assert.Nil(t, err)
+	val1, err := str.Get()
+	assert.Nil(t, err)
+	assert.Equal(t, "1", val1)
+	assert.Equal(t, "3", s.Selected)
+
+	s.SetSelected("2")
+	val1, err = str.Get()
+	assert.Nil(t, err)
+	assert.Equal(t, "1", val1)
+	assert.Equal(t, "2", s.Selected)
+}
+
 func TestSelect_ChangeTheme(t *testing.T) {
 	test.NewTempApp(t)