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To demonstrate how more complex types can be connected we will look at the List widget and how data binding can make it easier to use. Firstly we create a StringList data binding, which is a list of String data type. Once we have a data of list type we can connect this to the standard List widget. To do so we use the widget.NewListWithData constructor, much like other widgets.

Comparing this code to the list tour You will see 2 main changes, the first is that we pass the data type as the first parameter instead of a length callback function. The second change is the last parameter, our UpdateItem callback. The revised version takes a binding.DataItem value instead of widget.ListIndexID. When using this callback structure we should Bind to the template label widget instead of calling SetText. This means that if any of the strings change in the data source each affected row of the table will refresh.

package main

import (
	"fmt"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/data/binding"
	"fyne.io/fyne/v2/widget"
)

func main() {
	myApp := app.New()
	myWindow := myApp.NewWindow("List Data")

	data := binding.BindStringList(
		&[]string{"Item 1", "Item 2", "Item 3"},
	)

	list := widget.NewListWithData(data,
		func() fyne.CanvasObject {
			return widget.NewLabel("template")
		},
		func(i binding.DataItem, o fyne.CanvasObject) {
			o.(*widget.Label).Bind(i.(binding.String))
		})

	add := widget.NewButton("Append", func() {
		val := fmt.Sprintf("Item %d", data.Length()+1)
		data.Append(val)
	})
	myWindow.SetContent(container.NewBorder(nil, add, nil, nil, list))
	myWindow.ShowAndRun()
}

In our demo code there is an “Append” Button, when tapped it will append a new value to the data source. Doing so will automatically trigger the data change handlers and expand the List widget to display the new data.