TextEditingController in Flutter

Introduction

If a widget has editable text, the value must be stored somewhere. Saving the value of text in a state variable is the most basic technique. Another useful technique is to make a text editing controller flutter the controller of a TextField or TextFormField. Every time the user modifies the text field, the controller notifies its listeners so they are informed of the text and selection properties. The text editing controller flutter allows you to edit both the text and the selection. In this case, the controller will notify the text field so that it can adjust the view.

Creating and Initializing a TextEditingController

Just call the constructor to create a new TextEditingController.

The starting text is empty if you call it without the parameter. Typically, it is kept in a state variable.

One can also choose to set the default value by including the text argument.

Controlling Text Input

A TextEditingValue is a necessary parameter for the fromValue named constructor, which is another way to build a TextEditingController.

Here is an example of how to use fromValue.

For the controller to monitor changes to a text field's value, the field must be bound to the controller.

Managing Text Selection

Simply access the controller's text property to obtain the value.

Use the selection property to access the TextSelection's offset, affinity, and other properties.

By giving the text property a new value, Developers can change the text value programmatically. The cursor will automatically go to the start of the text by default. One must set the selected property as indicated below if they want to move the cursor elsewhere in the text editing controller flutter.

Flutter offers the clear() method for clearing the text.

Responding to Text Changes

From a text editing controller flutter, a TextSpan is easily constructed.

style is the TextStyle to be applied on the generated TextSpan. withComposing is used to make the text appear in underline if value.composing.isValid is true.

Although both are optional, It is advised to set withComposing because it occasionally may have a null value.

Disposing and Memory Management

If you're using a text editing controller flutter within a stateful widget, you can override the dispose() method of the widget's state to dispose of the controller.

Use Cases and Best Practices

To interact with and manage the text in a text field or text editing widget, use Flutter's TextEditingController class. When utilizing the text editing controller Flutter, the following use cases and recommended practices should be followed:

• Capturing user input:
  The user-entered text in a text field can be retrieved and altered using the TextEditingController tool. The controller's text property allows you to access the entered text. This is helpful in situations where processing or validating user input is necessary.

• Updating the text field:
  By setting the text property of the TextEditingController, you can update the text that appears in a text field programmatically. This is useful if you want to dynamically pre-fill or change the text field based on particular circumstances or events.

• Listening to text changes:
  You can use the addListener callback that the TextEditingController offers to listen for text changes. When the text in the text box is changed, you may utilize this to trigger actions. For instance, you could update a filtered list based on the search query or enable/disable a button based on the accuracy of the input.

• Clearing the text field:
  You can use the text editing controller flutter's clear() function to remove all of the text from a text field. This is helpful if you want to give users an easy way to remove material from text fields.

Best Practices:

• When necessary, create a TextEditingController instance and dispose of it in the appropriate lifecycle function of your widget (for example, initState() in a stateful widget).

• A text editing controller flutter instance should not be created more than once for a single text field. To preserve a consistent state and prevent idling memory, reuse the same controller instance across various widget rebuilds.

• For tasks like validation or updating UI elements that depend on text changes, use the addListener callback. When executing pricey procedures inside the listener, keep in mind any potential performance consequences.

Example Application

The output Looks like this :