From Scratch: Flask Form Handling and WTForms Validation
This article introduces the core knowledge of handling forms in Flask using the Flask-WTF extension. Flask-WTF is built on WTForms and provides form creation, validation, and CSRF protection. For environment preparation, install `flask` and `flask-wtf`. The core is defining form classes that inherit from `FlaskForm`, using field types like `StringField` and `PasswordField`, and pairing them with validators such as `DataRequired` and `Email` to define rules (e.g., non-empty, format, length). In view functions, instantiate the form and use `form.validate_on_submit()` to handle POST requests and validate data integrity. Templates should use `form.hidden_tag()` to generate CSRF tokens and loop through `form.xxx.errors` to display error messages. After successful validation, retrieve data from `form.xxx.data` and combine it with database storage (e.g., SQLAlchemy). Key process: Define form class → View processing → Template rendering → Data validation and processing. Use WTForms validators to implement checks for non-empty, format, etc., combined with CSRF protection for security, enabling rapid construction of reliable form systems.
Read MoreBootstrap 5 Forms Fundamentals: Inputs, Dropdowns, and Validation Tips
This article introduces Bootstrap 5 form development, which offers advantages such as rapid beautification, responsive layout, and reduced style code, making it suitable for beginners. The core content includes: basic input fields implemented using the form-label and form-control classes, supporting various types such as text, password, and email, with the need to associate id and for attributes. Dropdown menus are divided into basic ones (using the form-select class) and multi-select ones (from the dropdown series, requiring JavaScript). Form validation utilizes HTML5's required attribute to mark mandatory fields, the type attribute to check format, and is combined with is-valid/invalid classes to display feedback. It also provides comprehensive examples (multi-column layout, validation rules) and methods to introduce Bootstrap (CSS + JS), facilitating the quick construction of fully functional forms.
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