Blazor Dropdown List Example - Form Validation
This example demonstrates DropDownList integration within an EditForm using Data Annotations validation. The sample shows how to combine a DropDownList with Blazor’s validation pipeline so that selected values are validated against model attributes and invalid entries produce clear, inline feedback for the user.
Validation features:
- Place the DropDownList inside an
EditFormand bind its value to a model property to participate in form validation. - Validate inputs using
DataAnnotationsValidator, which evaluates standard data-annotation attributes on the bound model. - Choose valid values from the dropdown; selection updates the model and satisfies the validator when constraints are met.
- When input does not satisfy declared attributes, descriptive error messages are displayed adjacent to the field to guide correction.
Validation rules applied:
- Required — the field must have a non-empty, valid value before the form can be submitted successfully.
Form behavior and usage:
- Click the Submit button to trigger form validation; invalid fields are marked and error messages are shown until corrected.
- Valid selections from the DropDownList clear errors and allow the form to proceed with submission or subsequent processing.
- The sample emphasizes typical validation workflows—binding, declaration of attributes, user selection, and visual feedback—so developers can adopt the pattern consistently across forms.
This concise example serves as a practical reference for combining DropDownList controls with Data Annotations validation in Blazor EditForm scenarios. It demonstrates common patterns for enforcing required fields and presenting user-friendly error messages while preserving standard selection behavior.