If a requested resource is not found by the Service Layer returning null to the Web API controller; what is the best way to throw a HttpStatusCode.NotFound response back to the client without hard coding it in the controller, and by checking if it's null?
Personally I would just do the checks in the controllers as per Oppositional's comment but what you are asking for is perfectly reasonable. Again using action filters either attached per controller (or registered globally) you could do something along these lines:
Example Model:
public class Foo
{
public string Bar { get; set; }
}
Example Controller:
public class FoosController : ApiController
{
[NullObjectActionFilter]
public Foo Get(string id)
{
// - Returns model and 200
//return new Foo() { Bar = "TEST" };
// - Returns 404
//return null;
}
}
The Filter:
public class NullObjectActionFilter : ActionFilterAttribute
{
public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
{
object outValue = null;
actionExecutedContext.Response.TryGetContentValue<object>(out outValue);
if (outValue == null)
{
throw new HttpResponseException(HttpStatusCode.NotFound);
}
base.OnActionExecuted(actionExecutedContext);
}
}
I agree with Mark that the ActionFilter is the way to go - small action methods are a good smell.
However, HttpActionExecutedContext.Response can be null when an exception occurs; and the NullObjectActionFilter class shown above can obscure error HTTP status codes. You're better off checking for successful exit and a successful HTTP code.
Here's an action filter I use:
/// <summary>
/// Converts <c>null</c> return values into an HTTP 404 return code.
/// </summary>
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
public sealed class NullResponseIs404Attribute : ActionFilterAttribute
{
public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
{
if ((actionExecutedContext.Response != null) && actionExecutedContext.Response.IsSuccessStatusCode)
{
object contentValue = null;
actionExecutedContext.Response.TryGetContentValue<object>(out contentValue);
if (contentValue == null)
{
actionExecutedContext.Response = actionExecutedContext.Request.CreateErrorResponse(HttpStatusCode.NotFound, "Object not found");
}
}
}
}
Related
I tried to convert ASP.NET WEB API to ASP.NET CORE WEB API and have errors
My code in ASP.NET WebAPI
public class TestController : ApiController
{
// GET /test
public object Get()
{
return "get";
}
// GET /test?id={id}
public object Get(string id)
{
return id;
}
// GET /test?id={id}&anyParam={anyParam}
public object Get(string id, string anyParam)
{
return id + anyParam;
}
}
config.Routes.MapHttpRoute("Controller", "{controller}");
Try to convert it to ASP.NET Core 2.1 / 3.0
[ApiController]
[Route("{controller}")]
public class TestController : ControllerBase
{
// GET /test
public object Get()
{
return "get";
}
// GET /test?id={id}
public object Get(string id)
{
return id;
}
// GET /test?id={id}&anyParam={anyParam}
public object Get(string id, string anyParam)
{
return id + anyParam;
}
}
services.AddControllers();
app.UseRouting();
app.UseEndpoints(endpoints => { endpoints.MapControllers(); });
And i have in ASP.NET Core
AmbiguousMatchException: The request matched multiple endpoints
The sensible solution is just have one method that takes three parameters.
But, sensible solutions don't make for the most interesting stackoverflow answers, so here is how you can do this with two custom attributes, one which states the parameters that are required, and another which states which parameters are excluded:
public class RequireRequestParameterAttribute : ActionMethodSelectorAttribute
{
private readonly string[] _requiredNames;
public RequireRequestParameterAttribute(params string[] names)
{
this._requiredNames = names;
}
public override bool IsValidForRequest(
RouteContext routeContext,
ActionDescriptor action
) =>
this._requiredNames
.All(
routeContext
.HttpContext
.Request
.Query
.ContainsKey
);
}
public class DisallowRequestParameterAttribute : ActionMethodSelectorAttribute
{
private readonly string[] _forbiddenNames;
public DisallowRequestParameterAttribute(params string[] names)
{
this._forbiddenNames = names;
}
public override bool IsValidForRequest(
RouteContext routeContext,
ActionDescriptor action
) =>
!(this._forbiddenNames
.Any(
routeContext
.HttpContext
.Request
.Query
.ContainsKey
)
);
}
Now you can apply the attributes as follows:
[ApiController]
[Route("[controller]")]
public class TestController : ControllerBase
{
// GET test
public object Get()
{
return "Get";
}
// GET test?id={id}
[RequireRequestParameter("id")]
[DisallowRequestParameter("anyParam")]
public object Get(string id)
{
return id;
}
// GET test?id={id}&anyParam={anyParam}
[RequireRequestParameter("id", "anyParam")]
public object Get(string id, string anyParam)
{
return $"{id}: {anyParam}";
}
}
This means if you add another method with a third parameter, you have the maintenance burden of adding or modifying the DisallowRequestParameter attribute on the other methods.
I look your generated urls on actions and they are both /test which cause AmbiguousMatchException because your parameters are GET and are optional.
I think you can have same names on actions but you need define different ROUTE attribute (diff urls) on actions. Eg. you can not use default route with polymorphism on controller actions.
[Route("Home/About")]
MVC controllers Mapping of controllers now takes place inside
UseEndpoints.
Add MapControllers if the app uses attribute routing.
Source
https://learn.microsoft.com/cs-cz/aspnet/core/mvc/controllers/routing?view=aspnetcore-3.0#attribute-routing
Thanks to daremachine with his answer I was able to find information on Google
First step in ASP.NET Core we need class which inherit ActionMethodSelectorAttribute
public class RequireRequestValueAttribute : ActionMethodSelectorAttribute
{
public RequireRequestValueAttribute(string name, string value = null)
{
Name = name;
Value = value;
}
public string Name { get; }
public string Value { get; }
public StringComparison ComparisonType { get; } = StringComparison.OrdinalIgnoreCase;
private bool ValueIsValid(object value)
{
return ValueIsValid(value?.ToString());
}
private bool ValueIsValid(string value)
{
if (Value == null)
{
return true;
}
return string.Equals(value, Value, ComparisonType);
}
public override bool IsValidForRequest(RouteContext routeContext, ActionDescriptor action)
{
var value = default(object);
if (routeContext.RouteData.Values.TryGetValue(Name, out value) && ValueIsValid(value))
return true;
if (routeContext.RouteData.DataTokens.TryGetValue(Name, out value) && ValueIsValid(value))
return true;
if (routeContext.HttpContext.Request.Query.ContainsKey(Name))
{
var values = routeContext.HttpContext.Request.Query[Name];
if (values.Count <= 0)
{
if (ValueIsValid(null))
return true;
}
else if (values.Any(v => ValueIsValid(v)))
return true;
}
return false;
}
}
Then we can add to question methods [RequireRequestValue("")], the controller will look like this
[ApiController]
[Route("{controller}")]
public class TestController : ControllerBase
{
// GET /test
public object Get()
{
return "get";
}
// GET /test?id={id}
[RequireRequestValue("id")]
public object Get(string id)
{
return id;
}
}
But it can't polymorphism two similar fields, type id in my question
For asp net core 2. If you try to implement the same logic as was in web api controllers then use Microsoft.AspNetCore.Mvc.WebApiCompatShim. This nuget package provides compatibility in ASP.NET Core MVC with ASP.NET Web API 2 to simplify migration of existing Web API implementations. Please check this answer. Starting with ASP.NET Core 3.0, the Microsoft.AspNetCore.Mvc.WebApiCompatShim package is no longer available.
I have a logic to apply in case the request received is a BadRequest, to do this I have created a filter:
public class ValidateModelAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext context)
{
if (!context.ModelState.IsValid)
{
// Apply logic
}
}
}
In Startup:
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc(options => { options.Filters.Add<ValidateModelAttribute>(); });
}
Controller:
[Route("api/[controller]")]
[ApiController]
public class VerifyController : ControllerBase
{
[Route("test")]
[HttpPost]
[ValidateModel]
public ActionResult<Guid> validationTest(PersonalInfo personalInfo)
{
return null;
}
}
Model:
public class PersonalInfo
{
public string FirstName { get; set; }
[RegularExpression("\\d{4}-?\\d{2}-?\\d{2}", ErrorMessage = "Date must be properly formatted according to ISO 8601")]
public string BirthDate { get; set; }
}
The thing is when I put a break point on the line:
if (!context.ModelState.IsValid)
execution reaches this line only if the request I send is valid. Why it is not passing the filter if I send a bad request?
The [ApiController] attribute that you've applied to your controller adds Automatic HTTP 400 Responses to the MVC pipeline, which means that your custom filter and action aren't executed if ModelState is invalid.
I see a few options for affecting how this works:
Remove the [ApiController] attribute
Although you can just remove the [ApiController] attribute, this would also cause the loss of some of the other features it provides, such as Binding source parameter inference.
Disable only the Automatic HTTP 400 Responses
Here's an example from the docs that shows how to disable just this feature:
services.AddControllers()
.ConfigureApiBehaviorOptions(options =>
{
// ...
options.SuppressModelStateInvalidFilter = true;
// ...
}
This code goes inside of your Startup's ConfigureServices method.
Customise the automatic response that gets generated
If you just want to provide a custom response to the caller, you can customise what gets returned. I've already described how this works in another answer, here.
An example of intersection for logging is describe in Log automatic 400 responses
Add configuration in Startup.ConfigureServices.
services.AddControllers()
.ConfigureApiBehaviorOptions(options =>
{
// To preserve the default behavior, capture the original delegate to call later.
var builtInFactory = options.InvalidModelStateResponseFactory;
options.InvalidModelStateResponseFactory = context =>
{
var logger = context.HttpContext.RequestServices.GetRequiredService<ILogger<Startup>>();
// Perform logging here.
//E.g. logger.LogError($”{context.ModelState}”);
logger.LogWarning(context.ModelState.ModelStateErrorsToString());
// Invoke the default behavior, which produces a ValidationProblemDetails response.
// To produce a custom response, return a different implementation of IActionResult instead.
return builtInFactory(context);
};
});
public static String ModelStateErrorsToString(this ModelStateDictionary modelState)
{
IEnumerable<ModelError> allErrors = modelState.Values.SelectMany(v => v.Errors);
StringBuilder sb = new StringBuilder();
foreach (ModelError error in allErrors)
{
sb.AppendLine($"error {error.ErrorMessage} {error.Exception}");
}
return sb.ToString();
}
As the attribute filter in the life cycle of the .Net Core you can’t handle it. The filter layer with ModelState will run after the model binding.
You can handle it with .Net Core middleware as the following https://learn.microsoft.com/en-us/aspnet/core/fundamentals/middleware/?view=aspnetcore-2.1&tabs=aspnetcore2x
If you want to SuppressModelStateInvalidFilter on individual action, consider to use custom attribute suggested on https://learn.microsoft.com/en-us/answers/questions/297568/how-to-suppress-suppressmodelstateinvalidfilter-at.html. (And similar answer https://github.com/aspnet/Mvc/issues/8575)
public class SuppressModelStateInvalidFilterAttribute : Attribute, IActionModelConvention
{
private const string FilterTypeName = "ModelStateInvalidFilterFactory";
public void Apply(ActionModel action)
{
for (var i = 0; i < action.Filters.Count; i++)
{
//if (action.Filters[i] is ModelStateInvalidFilter)
if (action.Filters[i].GetType().Name == FilterTypeName)
{
action.Filters.RemoveAt(i);
break;
}
}
}
}
Example of use
[ApiController]
public class PersonController
{
[SuppressModelStateInvalidFilter]
public ActionResult<Person> Get() => new Person();
}
I'm having a problem trying to get custom model binders to work as a query parameter like I have gotten to work previously in .net framework 4.7.
To ensure this wasn't a scenario where my object was too complex, I reduced the model to a simple string but even then I cannot get this to work.
I have a simple model I would like to be binded from query parameters.
public class SearchModel {
public string SearchTerms { get; set; }
}
And I have configured the ModelBinder and ModelBinderProvider as shown here like so.
public class TestModelBinder : IModelBinder {
public Task BindModelAsync(ModelBindingContext bindingContext) {
if (bindingContext.ModelType != typeof(SearchModel)) {
throw new ArgumentException($"Invalid binding context supplied {bindingContext.ModelType}");
}
var model = (SearchModel)bindingContext.Model ?? new SearchModel();
var properties = model.GetType().GetProperties();
foreach(var p in properties) {
var value = this.GetValue(bindingContext, p.Name);
p.SetValue(model, Convert.ChangeType(value, p.PropertyType), null);
}
return Task.CompletedTask;
}
protected string GetValue(ModelBindingContext context, string key) {
var result = context.ValueProvider.GetValue(key);
return result.FirstValue;
}
}
public class TestModelBinderProvider : IModelBinderProvider {
public IModelBinder GetBinder(ModelBinderProviderContext context) {
if (context == null) {
throw new ArgumentNullException(nameof(context));
}
if (context.Metadata.ModelType == typeof(SearchModel)) {
var returnType = new BinderTypeModelBinder(typeof(TestModelBinder));
return returnType;
}
return null;
}
}
As stated in the last step in Microsoft documentation I updated my ConfigureServices method in Startup.cs to include the BinderProvider.
services.AddMvc(options => {
options.ModelBinderProviders.Insert(0, new TestModelBinderProvider());
})
.SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
But when I call my Search endpoint with a url such as "https://localhost:44387/api/testbinding?searchTerms=newSearch" I am always seeing a return of "request == null True" even though I see it properly hit the custom binding and bind correctly if I step through debugging, can anyone please point me in the right direction as to what I am doing wrong?
[Route("api/[controller]")]
[ApiController]
public class TestBindingController : ControllerBase {
[HttpGet()]
public IActionResult GetResult([FromQuery] SearchModel request) {
return Ok($"request == null {request == null}");
}
}
I think what you're missing if the statement that sets the result of the model binding operation, as you can see in the AuthorEntityBinder code sample in this section of the docs:
bindingContext.Result = ModelBindingResult.Success(model);
Your implementation of the model binder does create an instance of SearchModel, but doesn't feed it back to the model binding context.
As a separate note, I don't think you need to add a custom model binder is the query string segments match the properties names of the model you're trying to bind.
I have got a task to make Custom BreadCrumbs which will keep historical info of where the user got to the current point in an application. I have made a class for this purpose which Inherits from ActionFilterAttribute class and decorated the actions of the controller with that class, then in my OnActionExecuting override i save the historical view in a cookie and get the information out of the cookie in my customBreadCrumb partial view.
Moreover, my customBreadCrumb partial view is inside of another partail view which in turn is in the Layout page.
The problem is that every time the code executes it returns old cookie value. To be more specific it returns previous value in current view.
Here is my sample code.
public class CustomBreadCrumb : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
WriteCookie(string cValue);
base.OnActionExecuting(filterContext);
}
private void WriteCookie(string CookieValue)
{
HttpCookie breadCrumbCookie = new HttpCookie("MyCookie");
breadCrumbCookie.Value = CookieValue;
breadCrumbCookie.Expires = DateTime.Now.AddYears(1);
HttpContext.Current.Response.Cookies.Add(breadCrumbCookie);
}
public static string GetBreadCrumb()
{
if (HttpContext.Current.Request.Cookies["MyCookie"] != null)
{
return HttpContext.Current.Request.Cookies["MyCookie"].Value;
}
return string.Empty;
}
}
Here is my View
#{
#CustomBreadCrumb.GetBreadCrumbs()
}
Here is my sample controller
public class HomeController : BaseController
{
[CustomBreadCrumb]
public ActionResult Index(int ID = 1)
{
//My logic
}
}
I am working with asp.net WebAPI and I need to create a custom ActionFilter that does a quick check to see if the user requesting the URI should actually be able to get data back.
They have already been authorized to use the web service via basic auth and their role has been validated via a custom role provider.
The last thing I need to do is to check that they have permission to view the data they are requesting with a parameter in their URI.
Here is my code:
public class AccessActionFilter : FilterAttribute, IActionFilter
{
public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> ExecuteActionFilterAsync(HttpActionContext actionContext, System.Threading.CancellationToken cancellationToken, Func<System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage>> continuation)
{
var result = //code to see if they have permission returns either 0 or 1
if (result==0) {
throw new ArgumentException("You do not have access to this resource");
}
return continuation();
}
}
Currently I just throw an error which is not what I want, I'd rather return System.Net.HttpStatusCode.Unauthorized but I am a little miffed by the method I am overriding and I do not really understand it completely.
How would I go about returning that value?
You are probably best sticking to an exception but using the HttpResponseException which will return an Http status code too.
throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.Unauthorized));
Good question here about this.
p.s.
It may be simpler/cleaner to implement ActionFilterAttribute
public class AccessActionFilter : ActionFilterAttribute
{
public override void OnActionExecuting(HttpActionContext actionContext)
{
var result = //code to see if they have permission returns either 0 or 1
if (result==0)
{
throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.Unauthorized));
}
base.OnActionExecuting(actionContext);
}
}
Instead of throwing exception you can set status code
public class ExecutionFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(HttpActionContext actionContext)
{
var result = 0;//code to see if they have permission returns either 0 or 1
if (result == 0)
{
actionContext.Response = new HttpResponseMessage()
{
StatusCode = HttpStatusCode.Unauthorized,
Content = new StringContent("Unauthorized User")
};
}
base.OnActionExecuting(actionContext);
}
}