This post describes how to use dependency injection with ValidationAttributes in ASP.NET Core, and the process I took in trying to figure out how! ![]() The documentation on creating custom attributes is excellent, covering both server side and client side validation, but it doesn't mention this, presumably relatively common, requirement. The selected seat could then be displayed in an input field and then sent back to the server to determine whether the seat is still available or not.I was battling the other day writing a custom DataAnnotations ValidationAttribute, where I needed access to a service class to perform the validation. For example: imagine that a user is buying online tickets for an event, and selecting a seat number displayed on a seating chart. So, when would you actually use something like this? Any scenario where a selection/entry needs to be validated by the server can provide a better user experience by providing a result as the user is typing, instead of waiting for a form submission. If validation has passed, you would use Json(true) to indicate that the validation has passed. Instead of a text string, you can also use a false, null, or undefined value to indicate an invalid result. You may notice that if the validation fails, the controller action method returns a JSON response with an appropriate error message in a string. M圜ontrollerName), you would define an action method with the name specified in the attribute parameters, e.g. The model property would look something like this: This attribute is available in the namespace, from the NuGet package. You would then pass it the name of a server-side action method which returns an IActionResult with a true boolean result for a valid field. If you need to call a server-side method while performing client-side validation, you can use the attribute on a model property. ClientValidationEnabled = false Īlso mentioned in the official docs, the following code can be used for your Razor Pages, within the ConfigureServices() method of your Startup.cs class. NET Core to include built-in validation, with the ability to track whether a submitted form is valid or invalid.)įrom the official docs, the following code should be used within the ConfigureServices() method of your Startup.cs class, to set ClientValidationEnabled to false in your HTMLHelperOptions configuration. ![]() (Blazor makes use of the aforementioned EditForm element in ASP. If you ever need to disable client-side validation for some reason, that can be accomplished in different ways, whether it’s for an MVC view or a Razor page. Note that the syntax is identical whether it’s an MVC view or a Razor page.
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