Model validation in ASP.NET Core MVC and Razor Pages
webapi:Create web APIs with ASP.NET Core
Automatic HTTP 400 responses
The [ApiController] attribute makes model validation errors automatically trigger an HTTP 400 response. Consequently, the following code is unnecessary in an action method:
if (!ModelState.IsValid) { return BadRequest(ModelState); } ASP.NET Core MVC uses the ModelStateInvalidFilter action filter to do the preceding check.
Default BadRequest response
With a compatibility version of 2.1, the default response type for an HTTP 400 response is SerializableError. The following request body is an example of the serialized type:
{
"": [ "A non-empty request body is required." ] } With a compatibility version of 2.2 or later, the default response type for an HTTP 400 response is ValidationProblemDetails. The following request body is an example of the serialized type:
{
"type": "https://tools.ietf.org/html/rfc7231#section-6.5.1", "title": "One or more validation errors occurred.", "status": 400, "traceId": "|7fb5e16a-4c8f23bbfc974667.", "errors": { "": [ "A non-empty request body is required." ] } } The ValidationProblemDetails type:
- Provides a machine-readable format for specifying errors in web API responses.
- Complies with the RFC 7807 specification.
Log automatic 400 responses
See How to log automatic 400 responses on model validation errors (aspnet/AspNetCore.Docs #12157).