The logic will be defined as such:įirst, for the name field, we want the user to enter a valid first name and last name, which can be accompanied by initials.įor the email field, we want a valid email that contains some characters before the sign, as well as the email domain at the end of the email.įor phone number validation, the user is expected to input 11 digits starting with the digit zero.įinally, for our password validation, we expect the user to use a combination of an uppercase letter, a lowercase letter, a digit, and special character. Creating a form in Flutterįirst, we are going to create a simple login page that has the following fields:įor the validation, we want the users of our app to fill in the correct details in each of these fields. You can find more information on these two approaches in the official Flutter docs. In this article, we’ll cover two approaches to form validation: the form widget and the Provider package. The Flutter SDK provides us with an out-of-the-box widget and functionalities to make our lives easier when using form validation. Getting started with form validation in Flutter Using Regex methods and Dart extension methods.Getting started with form validation in Flutter.At the end of this blog post, you will be able to apply the concepts to all of your future app development projects. The aim of this article is to provide you with a grasp of how a neat and scalable implementation of form validation in Flutter works. With Flutter and its increasing popularity, we will explore how form validation works and alternative ways to make it work more efficiently. You can find more details in the TextEditingController documentation.Īnd if you want to learn more about working with forms, check the official documentation on ’s note: This article was last updated on 25 February 2022 to include information for a more comprehensive guide to form validation in Flutter, including form validation with the Provider package, custom form fields, and Regex and Dart extension methods.įorm validation is an integral part of most applications, and an essential tool in the arsenal of any mobile application developer. With that said, TextEditingController gives you more fine-grained control and lets you get and set the text, which can be handy when you need to pre-fill a text field. I recommend using Form and TextFormField, as they give you some high-level APIs that make it easier to work text input, and they are better suited if you have multiple form fields on the same page. Flutter Form Validation with TextFormField.Flutter TextField Validation with TextEditingController. You can find the complete source code and play with both solutions on Dartpad: We have now explored two different ways of validating a form in Flutter. A fully managed API for developers that enables you to generate beautiful PDF or screenshots and store them directly in your own S3 bucket without compromising privacy. Help me keep it that way by checking out this sponsor: This is an enum defined as follows:Ĭode with Andrea is free for everyone. To decide when the TextFormField validation takes place, we can pass an autovalidateMode argument. The Flutter FormState class gives us validate and save methods that make it easier to manage the form data. If this is successful, we notify the parent widget by calling widget.onSubmit(_name). Inside the _submit() method, we call _formKey.currentState!.validate() to validate all the form data.We use a separate _name state variable and update it in the onChanged callback of the TextFormField widget (note how this is used in the onPressed callback of the ElevatedButton).This takes a validator function argument that we can use to specify our validation logic.
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