Multiple HTTPGET methods in ASP.NET CORE WEB-API

Question

I started to experiment on ASP.NET Core WEB API and while writing a controller to assist multiple get requests which are differed by number of parameters,I am getting the below error.

Microsoft.AspNetCore.Routing.Matching.AmbiguousMatchException: The request matched multiple endpoints. Matches:

PaperRocket.Controllers.Products.ProductsController.GetProducts (PaperRocket) PaperRocket.Controllers.Products.ProductsController.GetProduct (PaperRocket) at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.ReportAmbiguity(CandidateState[] candidateState) at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.ProcessFinalCandidates(HttpContext httpContext, CandidateState[] candidateState) at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.Select(HttpContext httpContext, CandidateState[] candidateState) at Microsoft.AspNetCore.Routing.Matching.DfaMatcher.MatchAsync(HttpContext httpContext) at Microsoft.AspNetCore.Routing.Matching.DataSourceDependentMatcher.MatchAsync(HttpContext httpContext) at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext) at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

HEADERS ======= Accept: / Accept-Encoding: gzip, deflate, br Cache-Control: no-cache Connection: keep-alive Host: localhost:54967 User-Agent: PostmanRuntime/7.24.1 Postman-Token: 0f3ce4b4-283a-472b-9350-7b0cc02d31ae

So, my question is, can we have multiple get Methods

1. which are differed by number of parameters(Which is possible in WEB-API)
2. Without using HTTPGET("RouteConstraint")-(I know with this, it will work)
3. respective method should get called and identified by the the parameters that we passed

Below is my code:

    [HttpGet]
    public IEnumerable<Product> GetProducts()
    {
        return _Productcontext.GetProducts();
    }

    [HttpGet]
    public Product GetProduct([FromQuery(Name = "ProductCode")]string ProductCode)
    {
        return _Productcontext.GetProductByProductCode(ProductCode);
    }

Finally, Please direct me to any best model binding,routing in asp.net core articles and how they are different from the ASP.NET WEB-API.

Answer 1

Microsoft.AspNetCore.Routing.Matching.AmbiguousMatchException: The request matched multiple endpoints.

You can try to enable or disable an action for a given request based on query string that you passed by implementing a custom ActionMethodSelectorAttribute , like below.

[AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
public class CheckProductCodeAttribute : ActionMethodSelectorAttribute
{
    public string QueryStingName { get; set; }
    public bool CanPass { get; set; }
    public CheckProductCodeAttribute(string qname, bool canpass)
    {
        QueryStingName = qname;
        CanPass = canpass;
    }

    public override bool IsValidForRequest(RouteContext routeContext, ActionDescriptor action)
    {
        StringValues value;

        routeContext.HttpContext.Request.Query.TryGetValue(QueryStingName, out value);

        if (QueryStingName == "" && CanPass)
        {
            return true;
        }
        else
        {
            if (CanPass)
            {
                return !StringValues.IsNullOrEmpty(value);
            }

            return StringValues.IsNullOrEmpty(value);
        }
    }
}

Apply to your actions

[HttpGet]
[CheckProductCode("", true)]
[CheckProductCode("ProductCode", false)]
public IEnumerable<Product> GetProducts()
{
    return _Productcontext.GetProducts();
}

[HttpGet]
[CheckProductCode("", false)]
[CheckProductCode("ProductCode", true)]
public Product GetProduct([FromQuery(Name = "ProductCode")]string ProductCode)
{
    return _Productcontext.GetProductByProductCode(ProductCode);
}