# TextInputClient currentTextEditingValue

> Add a new field to the TextInputClient interface to get the current TextEditingValue from a client.




:::important
These breaking change docs are accurate, as of the release
under which they are published. Over time, the
workarounds described here might become inaccurate.
We don't, in general, keep these breaking change docs up
to date as of each release.

The [breaking change index file](/release/breaking-changes)
lists the docs created for each release.
:::


## Summary

Add a field, `currentTextEditingValue`, to the `TextInputClient`
interface to get the current value of an editable text field
from a platform client.

## Context

The `TextInputClient` class is used by the Flutter framework to
communicate with platform code about the current state of text
input widgets like `EditableText`.

The platform side can lose its state when an Android app
moves to the background. As of this change,
the app can ask the framework for the last known state.
In order to obtain this information,
the `TextEditingValue` was surfaced for the `TextInputClient`.

## Description of change

On some supported platforms, the application can be moved into
the background where it is expected to consume fewer resources.
For example, a backgrounded application on Android should avoid consuming
unnecessary memory and has no need to retain references to views.
Before this change, the Android-specific platform code could
lose state information about editable text fields when
the app moved back to the foreground.
This is seen, for example,
when text entered in a `TextField` widget is lost to
the Java code, but is still remembered in the Dart code.

As of this change,
the platform side now sends a `textInput` channel
message called `TextInput.requestExistingState`.
This notifies the Dart code that, when the app wakes up,
it should re-establish any text input connections
and notify the platform of its most
recently known editing state.

The `TextInput` class interacts with client widgets using
the `TextInputClient` interface. This interface previously
provided no insight into the current value that a client had.
To allow the `TextInput` class to appropriately respond to
`TextInput.requestExistingState`, a new getter was added to
`TextInputClient` called `currentTextEditingValue`.
You cannot safely use the last value passed to
`TextInputConnection.setEditingState`, since the client
only calls that method under specific circumstances,
such as when Dart code directly modifies the value of a
`TextEditingController` in a way that does not directly mirror
the platform's native handling of a response to a key input event.
This is how a `TextInputFormatter` generally works,
or what happens when Dart code directly sets
`TextEditingController.value`.

## Migration guide

If you previously implemented or extended `TextEditingClient`,
you must now add the appropriate override for `currentTextEditingValue`.

This value may be null.

If you want to migrate _before_ this change lands,
you can add a class to your class
similar to the following:

```dart
abstract class _TemporaryTextEditingClient {
  TextEditingValue get currentTextEditingValue;
}
```

This allows you to add the new member with an
`@override` annotation before the change lands
in the framework. Later, you can remove the
temporary interface definition.

Code before migration:

```dart
class _MyCustomTextWidgetState extends State<MyCustomWidget> implements TextEditingClient {
  ...

  @override
  void updateEditingValue(TextEditingValue value) {
    ...
  }

  @override
  void performAction(TextInputAction action) {
    ...
  }

  @override
  void updateFloatingCursor(RawFloatingCursorPoint point) {
    ...
  }
}
```

Code after migration:

```dart
class _MyCustomTextWidgetState extends State<MyCustomWidget> implements TextEditingClient {
  ...

  @override
  TextEditingValue get currentTextEditingValue => widget.textEditingController.value;

  @override
  void updateEditingValue(TextEditingValue value) {
    ...
  }

  @override
  void performAction(TextInputAction action) {
    ...
  }

  @override
  void updateFloatingCursor(RawFloatingCursorPoint point) {
    ...
  }
}
```

## Timeline

Landed in version: 1.16.3<br>
In stable release: 1.17

## References

API documentation:

* [`TextInput`][]
* [`TextInputClient`][]
* [`EditableText`][]
* [`SystemChannels.textInput`][]

Relevant issue:

* [Issue 47137][]

Relevant PR:

* [Fix requestExistingInputState response][]


[`EditableText`]: https://api.flutter.dev/flutter/widgets/EditableText-class.html
[Fix requestExistingInputState response]: https://github.com/flutter/flutter/pull/47472
[Issue 47137]: https://github.com/flutter/flutter/issues/47137
[`TextInput`]: https://api.flutter.dev/flutter/services/TextInput-class.html
[`TextInputClient`]: https://api.flutter.dev/flutter/services/TextInputClient-class.html
[`SystemChannels.textInput`]: https://api.flutter.dev/flutter/services/SystemChannels/textInput-constant.html