Examples.md

KBinding By Example:

Create a BindingHolder to contain our bindings:

val holder = BindingHolder(viewModel)

Bind the value of ObservableField<String> to the UI TextView:

// one way binding on Observable fields
holder.bindSelf { viewModel.name }.toText(textView)

Bind the field value of a normal String to the visibility Int:

// one way binding on non observables
holder.bind(ViewModel::name) { it.name }
    .onIsNotNullOrEmpty() // if null or empty return false
    .toShowHideView(someView) // if true show, if false hide.

Bind both changes of ObservableField<String> and EditText value changes:

// two way binding on observable that synchronizes text and value changes.
holder.bindSelf { it.name }
  .toText(input)
  .twoWay()
  .toFieldFromText()

Bind changes of ObservableField<Boolean> and a CheckBox change together:

// two way binding that synchronizes compoundbutton / checkbox changes
holder.bindSelf { it.selected }
        .toOnCheckedChange(checkbox)
        .twoWay()
        .toFieldFromCompound()

Back changes in UI from a TextView/EditText with an ObservableField<String>:

// binds input changes from the view to the name property.
holder.bind(textView)
    .onSelf()
    .to { it.name }

Back changes in UI from a TextView/EditText to a non-observable property:

// binds input changes from the view to the name property (non observable).
holder.bind(textView)
    .onSelf()
    .to { input, view -> it.name = input}

We support swapping top-level ViewModel in the BindingHolder:

holder.viewModel = viewModel // set the ViewModel (no restriction and could be a `Presenter`)
holder.viewModel = null // support null `ViewModel` too!
// if bound will reevaluate the bindings.

By default bindings are not executed when the ViewModel is null. If you wish to supply default values or execute when it is null, use:

// if normal binding, a default value for field is used and the expression is not evaluated.
// in this case it's executed always
holder.bindNullable(ViewModel::name) { it?.name }
  .onSelf()
  .toText(textView)

When done, cleanup bindings to prevent memory leaks! (BindingComponent for Anko does the cleanup for you when calling destroyView())

holder.unbindAll() // when done, unbind

We can also easily turn off individual bindings as needed, just hold a reference to it:

val binding = holder.bindSelf(textView).toObservable { it.name }
binding.unbind() // can turn off binding as needed