ModelState to check all parameters in Web Api - asp.net-web-api

Question

This is my action the ModelState checks only the bookId parameter. The other one even if it is null, no error is raised.
Is there any way to make it check the ModelState of all parameters?
[HttpPut]
[Route("{bookId}")]
public IHttpActionResult Edit([FromBody] EditBookBindingModel model, int bookId)
{
if (!this.service.ExistsBook(bookId))
{
return this.NotFound();
}
if (!this.ModelState.IsValid)
{
return this.StatusCode(HttpStatusCode.BadRequest);
}
this.service.EditBook(bookId, model);
return this.Ok();
}

Answer 1

You could define an ActionFilterAttribute that protects you from null arguments:
public class CheckModelForNullAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(HttpActionContext actionContext)
{
if (actionContext.ActionArguments.ContainsValue(null))
actionContext.Response = actionContext.Request.CreateErrorResponse(HttpStatusCode.BadRequest, "The argument cannot be null");
}
}
Then use this:
[HttpPut]
[Route("{bookId}")]
[CheckModelForNull]
public IHttpActionResult Edit([FromBody] EditBookBindingModel model, int bookId)
{
// model can´t be null now
...

Answer 2

I wrote a custom filter so DataAnnotations works with parameters also.
Here is the filter.
public class ModelValidationFilter : FilterAttribute, IActionFilter, IFilter
{
public Task<HttpResponseMessage> ExecuteActionFilterAsync(HttpActionContext actionContext,
CancellationToken cancellationToken, Func<Task<HttpResponseMessage>> continuation)
{
var parameters = actionContext.ActionDescriptor.GetParameters();
if (parameters.Any())
{
var validationParams = parameters.Where(x => x.GetCustomAttributes<ValidationAttribute>().Any());
if (validationParams.Any())
{
foreach (var item in validationParams)
{
var val = actionContext.ActionArguments[item.ParameterName];
foreach (var attr in item.GetCustomAttributes<ValidationAttribute>())
{
if (!attr.IsValid(val))
{
actionContext.ModelState.AddModelError(item.ParameterName, attr.FormatErrorMessage(item.ParameterName));
}
}
}
}
if (!actionContext.ModelState.IsValid)
{
return Task.FromResult(actionContext.Request.CreateErrorResponse(HttpStatusCode.BadRequest, actionContext.ModelState));
}
}
return continuation();
}
}
Usage (I have'nt tested completely.):
add it to global filters.
config.Filters.Add(new ModelValidationFilter());
public Student Post([Required] addStudentDTO)
{
//Your logic
}
public Student Patch([FromBody,Required] addStudentDTO, [Required,EmailAddress]string emailAddress])
{
//Your logic
}