Data Binding

Data binding is a powerful new addition to the Fyne toolkit that was introduced in version v2.0.0. By using data binding we can avoid manually managing many standard objects like Labels, Buttons and Lists.

The builtin bindings support many primitive types (like Int, String, Float etc), lists (such as StringList, BoolList) as well as Map and Struct bindings. Each of these types can be created using a simple constructor function. For example to create a new string binding with a zero value you can use binding.NewString(). You can get or set the value of most data bindings using Get and Set methods.

It is also possible to bind to an existing value using similar functions who’s names start Bind and they all accept a pointer to the type bound. To bind to an existing int we could use binding.BindInt(&myInt). By keeping a reference to a bound value instead of the original variable we can configure widgets and functions to respond to any changes automatically. If you change the external data directly, be sure to call Reload() to ensure that the binding system reads the new value.

We start learning about simple values widget binding next.

Example Code

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package main

import (
	"log"

	"fyne.io/fyne/v2/data/binding"
)

func main() {
	boundString := binding.NewString()
	s, _ := boundString.Get()
	log.Printf("Bound = '%s'", s)

	myInt := 5
	boundInt := binding.BindInt(&myInt)
	i, _ := boundInt.Get()
	log.Printf("Source = %d, bound = %d", myInt, i)
}
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