Select list validation in asp net core

TL;DR

Learn how to make a select list required and display validation errors in an ASP.NET Core application.

Transcript

this is Pat 43 of a speed or net core tutorial in this video let's discuss implementing validation on a select list in a spirit head core let's understand this with an example here's what we want to do make the department select list required we won the first option here to be pleased select this is not a valid Department selection but it is just a... Read More

Key Insights

• 👂 Implementing validation on a select list in ASP.NET Core requires adding the [Required] attribute to the corresponding property in the model class.
• 🫢 Validation error messages can be displayed using the <span asp-validation-for=""></span> tag helper.
• 👂 The underlying data type of an enum in ASP.NET Core is integer by default, which can impact validation on select lists.
• ⁉️ Making a value type nullable by adding a question mark allows for optional fields without the need for the [Required] attribute.

Questions & Answers

Q: How can we make the department select list required in an ASP.NET Core application?

To make the department select list required, we can add the [Required] attribute to the department property in the Employee class. This will ensure that a value is selected before submitting the form.

Q: How can we display a validation error message for the department select list?

We can use the <span asp-validation-for="Department"></span> tag helper to display the validation error message. This will show the error message when the form is submitted without a valid department selection.

Q: Why are we getting a "value empty string is invalid" error when submitting the form with the "please select" option selected?

The error occurs because the underlying data type for the department property is an enum, which by default has an underlying data type of integer. An empty string is not a valid value for an integer, hence the error message.

Q: How can we make the department field optional?

To make the department field optional, we can make its underlying data type nullable. We do this by adding a question mark after the enum type (e.g., Department?). This allows the field to be submitted without a value.

Summary & Key Takeaways

• This tutorial explains how to implement validation on a select list in an ASP.NET Core application.

• The goal is to make the department select list required and display a validation error if the user selects an invalid option.

• The tutorial covers binding the select list to an enum, hard coding a "please select" option, making the department property required, and displaying the validation error message.