EDIT: You can safely clone https://github.com/vslzl/68737969 and run the example. If you send
{
"intPropB":3
}
as POST body to: http://localhost:5000/api/Test
you'll see it binds clearly B object to A object.
#EDIT END
I'd like to implement alternate model binding using asp.net core 5 As you will see below, I have two alternative classes to bind at a single endpoint. Each request can contains only a valid A model or B model and A and B has different properties.
[HttpPost(Name = Add)]
public async Task<IActionResult> AddAsync(CancellationToken ct)
{
var aModel= new A();
var bModel= new B();
if (await TryUpdateModelAsync<A>(aModel))
{
_logger.LogDebug($"Model binded to A");
return Ok(aModel);
}
else if (await TryUpdateModelAsync<B>(bModel))
{
_logger.LogDebug($"Model binded to B");
return Ok(bModel);
}
_logger.LogDebug("Nothing binded!");
return BadRequest();
}
But this approach failed. Is there a proper way to implement this kind of solution?
By the way I'm using this to reduce complexity of my endpoints, I want to update a record partially and by doing this, each model will map the same record but with different logics.
Any suggestions will be appreciated. Thanks.
Couldn't manage to provide elegant way to do this but here is what I've done so far, It works but seems a little ugly in my opinion.
I changed the action method to this:
[HttpPost(Name = Add)]
[AllowAnonymous]
public IActionResult AddSync([FromBody] JObject body)
{
var aModel = JsonConvert.DeserializeObject<A>(body.ToString());
var bModel = JsonConvert.DeserializeObject<B>(body.ToString());
ModelState.Clear();
var aValid = TryValidateModel(aModel);
ModelState.Clear();
var bValid = TryValidateModel(bModel);
// some logic here...
return Ok(new {aModel,bModel, aValid, bValid });
}
I think It's not a good idea to interfere with ModelState this way.
But here is what I've done,
get the raw body of the request as JObject (requires Newtonsoft.Json package)
Parsed that json value to candidate objects
Check their validity via modelstate and decide which one to use.
Related
This question is a follow up to this post - How to perform async ModelState validation with FluentValidation in Web API?.
I was wondering if FluentValidation has a way to perform async ModelState validation in .net core web api. I have a FluentValidation Validator class which contains async validation methods such as "MustAsync", which means in my business service class I call the validator manually using "ValidateAsync". I also want to use this same validator class to validate the model coming in from the request. I went through the documents and read that the only way to do this is to manually call the "ValidateAsync()" method since the .net pipeline is synchronous. I would rather not manually have to call this method from within my controller, I would prefer to either register it in the startup (have the framework automatically call the the validator on my model) or decorate my request model with the validator.
Has anyone been able to achieve this?
Thanks!
Based on the linked question, I've adapted the code slightly to be compatible with ASP.NET Core (2.2, in my case). In general, this is using the IAsyncActionFilter interface. You can read about it in the official docs.
public class ModelValidationActionFilter : IAsyncActionFilter
{
private readonly IValidatorFactory _validatorFactory;
public ModelValidationActionFilter(IValidatorFactory validatorFactory) => _validatorFactory = validatorFactory;
public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
{
var allErrors = new Dictionary<string, object>();
// Short-circuit if there's nothing to validate
if (context.ActionArguments.Count == 0)
{
await next();
return;
}
foreach (var (key, value) in context.ActionArguments)
{
// skip null values
if (value == null)
continue;
var validator = _validatorFactory.GetValidator(value.GetType());
// skip objects with no validators
if (validator == null)
continue;
// validate
var result = await validator.ValidateAsync(value);
// if it's valid, continue
if (result.IsValid) continue;
// if there are errors, copy to the response dictonary
var dict = new Dictionary<string, string>();
foreach (var e in result.Errors)
dict[e.PropertyName] = e.ErrorMessage;
allErrors.Add(key, dict);
}
if (allErrors.Any())
{
// Do anything you want here, if the validation failed.
// For example, you can set context.Result to a new BadRequestResult()
// or implement the Post-Request-Get pattern.
}
else
await next();
}
}
If you want to apply this filter globally, you can add the filter to the AddMvc call in your Startup class. For example:
services.AddMvc(options =>
{
options.Filters.Add<ModelValidationActionFilter>();
// uncomment the following line, if you want to disable the regular validation
// options.ModelValidatorProviders.Clear();
});
I had trouble getting the code in #nachtjasmin's answer to work with newer versions of FluentValidation. Specifically, the trouble is that ValidateAsync now takes an IValidationContext instead of the model being validated, and the context can't be created without knowing the type of the model at compile time.
Eventually I stumbled upon this answer, which points out that the exact type is not important and uses object instead.
So, instead of:
var result = await validator.ValidateAsync(value);
You can use:
var context = new ValidationContext<object>(value);
var result = await validator.ValidateAsync(context);
Based on the answer above by #nachtjasmin, you can add this in two ways,
Using AddMvc
services.AddControllersWithViews(options =>
{
options.Filters.Add<FluentValidationActionFilter>();
});
Using AddControllersWithViews
services.AddControllersWithViews(options =>
{
options.Filters.Add<FluentValidationActionFilter>();
});
If your's is just a Web API and you don't have any Razor pages involved, then you can consider using AddControllersWithViews over AddMvc, as the AddMvc uses the AddControllersWithViews internally and add the services.AddRazorPages() on top of that.
You can see this info here for AddMvc and here for AddControllersWithViews
Upgrading to asp.net core 2.2 in my hobby project there is a new routing system I want to migrate to. Previously I implemented a custom IRouter to be able to set the controller for the request dynamically. The incoming request path can be anything. I match the request against a database table containing slugs and it looks up the a matching data container class type for the resolved slug. After that I resolve a controller type that can handle the request and set the RouteData values to the current HttpContext and passing it along to the default implementation for IRouter and everything works ok.
Custom implementaion of IRouter:
public async Task RouteAsync(RouteContext context)
{
var requestPath = context.HttpContext.Request.Path.Value;
var page = _pIndex.GetPage(requestPath);
if (page != null)
{
var controllerType = _controllerResolver.GetController(page.PageType);
if (controllerType != null)
{
var oldRouteData = context.RouteData;
var newRouteData = new RouteData(oldRouteData);
newRouteData.Values["pageType"] = page.PageType;
newRouteData.Values["controller"] = controllerType.Name.Replace("Controller", "");
newRouteData.Values["action"] = "Index";
context.RouteData = newRouteData;
await _defaultRouter.RouteAsync(context);
}
}
}
A controller to handle a specific page type.
public class SomePageController : PageController<PageData>
{
public ActionResult Index(PageData currentPage)
{
return View("Index", currentPage);
}
}
However I got stuck when I'm trying to figure out how I can solve it using the new system. I'm not sure where I'm suppose to extend it for this behavior. I don't want to turn off the endpoint routing feature because I see an opportunity to learn something. I would aso appreciate a code sample if possible.
In ASP.NET 3.0 there is an new dynamic controller routing system. You can implement DynamicRouteValueTransformer.
Documentation is on the way, look at the github issue
This first method is fine. But when I add the second method the body of the SWAGGER UI is a bunch of html gibberish. And I creating the route the wrong way?
// GET api/checklist/1288
[HttpGet("{id}")]
public async Task<IActionResult> Get(int id)
{
var model = _checkListService.Get(id);
return Ok(model);
}
// http://localhost:64783/api/checklist/GetDelinquentItems?id=1288
[Route("GetDelinquentItems")]
public async Task<IActionResult> GetDelinquentItems(int id)
{
var model = _checkListService.GetDelinquentItems(id);
return Ok(model);
}
That 'html gibberish' (indeed not the most elegant way to show an error) still contains some useful information. The first line says:
500 internal server error
and in the last three lines you can read:
Ambiguos HTTP method for action...CheckListController.GetDelinquentItems... Actions require explicit HttpMethod binding for Swagger
therefore another
[HttpGet("{id}")]
before the GetDelinquentItems() method should solve the problem.
MVC 4
I have an action that is decorated with an action filter like this:
[ViewPermission(PermissionType.GlobalUser)]
public ActionResult General()
{
var permissionType = // trying to access the value passed to the filter ie. PermissionType.GlobalUser value
return View();
}
Is there a way to get the properties from the acation filter inside the action itself?
Thanks in advance.
So the quick answer is yes, you can do it doing something like this:
[ViewPermission(PermissionType.GlobalUser)]
public ActionResult General()
{
var type = GetType(this);
var method = type.GetMethod("General");
var attribute(typeof(ViewPermission));
var permissionType = attribute.PermissionType;
return View();
}
With that said, it is NOT a good idea. Doing reflection is slow. Very slow. You would see performance problems. If you really need to do this, then it is best to figure out a way to do it during initialization of the app, where performance is not as much of a concern.
Hope that helps.
I wanted to take advantage of built-in content negotiator and just get access to decision what formatter is going to be used. I don't want to use Request.Headers.Accept and check for whether it is json or xml content type because there lot of things are involved in that decision. Is there a way I can check at controller level or override any class that tells me what formatter going to be used OR what request content type is?
thanks in advance.
You can run conneg manually:
var conneg = Configuration.Services.GetContentNegotiator();
var connegResult = conneg.Negotiate(
typeof(YOUR_TYPE), Request, Configuration.Formatters
);
And use the output whichever way you want:
//the valid media type
var mediaType = connegResult.MediaType;
//do stuff
//the relevant formatter
var formatter = connegResult.Formatter;
//do stuff
If you want to see what is going on then install a TraceWriter and you will see what the conneg does.
A TraceWriter looks something like:
public class TraceWriter : ITraceWriter {
public bool IsEnabled(string category, TraceLevel level) {
return true;
}
public void Trace(HttpRequestMessage request, string category, TraceLevel level, Action<TraceRecord> traceAction) {
var rec = new TraceRecord(request, category, level);
traceAction(rec);
Log(rec);
}
private void Log(TraceRecord record) {
Console.WriteLine(record.Message);
}
}
and is installed like this,
config.Services.Replace(typeof(ITraceWriter), new TraceWriter());
If you want to manually invoke conneg then you can use,
config.Services.GetContentNegotiator().Negotiate(...)
Tugberk has a blog on this. Have a look.