README.md

GD Data Binding

GD Data Binding is a Godot library that simplifies your UI coding by automatically syncing data between views and models.

Godot Asset Library

Demo

You can try it here.

Example

See the usage in examples.

MVVM

GD Data Binding is based on the MVVM pattern. In the pattern, the application UI and logic are separated into three components: View, ViewModel, and Model.

graph LR
  A(View)
  B(ViewModel)
  C(Model)
  A -- Data Binding --> B
  B -- Update --> C
  C -- Notify --> B
  B -- Notify --> A

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Reference: https://learn.microsoft.com/dotnet/architecture/maui/mvvm

GD Data Binding hides implementation between View and ViewModel. Therefore, all you need is to define how to bind View and data, and you don't need to care about syncing them.

For example, imagine to create a counter. The view has a label to show the counted number and a button to count up the number.

The basic way to update the label content is that the button-pressed handler increases the count value and assigns it to the text of the label.

var _data = Data.new()


func _ready():
	_update_label_text()


func _on_button_pressed():
	_data.count += 1
	_update_label_text()


func _update_label_text():
	$Label.text = "Count: %s" % _data.count


class Data:
	var count: int = 0

However, in this way, you must know that count is the content of $Label and update $Label.text when updating count.

Using GD Data Binding, the code can be rewritten like this;

var _data = BindingSource.new(Data.new())


func _ready():
	_data.bind(&"count").using(_get_label).to_label($Label)


func _on_button_pressed():
	_data.count += 1


static func _get_label(count: int):
	return "Count: %s" % count


class Data:
	var count: int = 0

BindingSource wraps data objects and provides binding functions.

In _ready, bind count and $Label.text. To convert the count value into the label content (e.g. count = 5 -> "Count: 5"), use _get_label.

In _on_button_pressed, only increase count, but not update $Label.text directly.

In the view of the MVVM pattern:

• View: _ready, _get_label
• ViewModel: _on_button_pressed
• Model: Data

The important point is that you can be unaware of View when defining ViewModel.