如何为具有不同参数的同一Controller方法设置不同的路由？

Question

I have the ReportController that llooks like this:

public IActionResult ReportDetails(int? reportId){
    ....
}

and

public IActionResult ReportDetails(int? reportId, bool ? approved) {
    ....
}

and I tried to do some routing, bu it failed. Actual code written in Startup.cs:

app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "ReportDetailsValidation",
                    template: "descriptionValidation",
                    defaults: new { controller = "Report", action = "ReportDetails", reportId ="{reportId}", approved = "{approved}" }
                    );

                routes.MapRoute(
                    name: "ReportDetails",
                    template: "description",
                    defaults: new { controller = "Report", action = "ReportDetails"} 
                    );

                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });

As I have seen I need to match the following URL's:
/Report/ReportDetails?reportId=7 for the first and
/Report/ReportDetails?reportId=7&approved=True for second

Answer 1

You can follow this link to understand routing

[HttpGet("Report/ReportDetails/{reportId}")] 
[HttpGet("Report/ReportDetails/{reportId}/{approved}")]
public IActionResult ReportDetails(int? reportId, bool? approved) {
....
}

Answer 2

You can create an ActionMethodSelectorAttribute . In your controller you can add your attribute to both methods to enable matching the correct method to the URL.

You could for example make a ParameterExistsAttribute that decides if the method is suitable and then use

[ParameterExists('approved', false)]
public IActionResult ReportDetails(int? reportId){
    ....
}

[ParameterExists('approved', true)]
public IActionResult ReportDetails(int? reportId, bool ? approved) {
    ....
}

The puzzle on how to implement such an attribute remains an exercise to the reader. (It's not so difficult.)

As an example here's an attribute that selects an API call, based on the value of a parameter.

public class FormPostFilterAttribute : ActionMethodSelectorAttribute
{
  private readonly string _elementId;
  private readonly string _requiredValue;

  public FormPostFilterAttribute(string elementId, string requiredValue)
  {
    _elementId = elementId;
    _requiredValue = requiredValue;
  }

  public override bool IsValidForRequest(ControllerContext controllerContext, System.Reflection.MethodInfo methodInfo)
  {
    if (string.IsNullOrEmpty(controllerContext.HttpContext.Request.Form[_elementId]))
    {
      return false;
    }

    return (controllerContext.HttpContext.Request.Form[_elementId] == _requiredValue);
  }
}

Answer 3

You can't do that, like have 2 methods with identical name with different parameters, because you should get AmbiguousActionException .

ASP Core Action Selector does not care about Action's parameters during select action. Therefore you can't have 2 actions correspond one route template. The only workaround is to play with action constraints (like HttpGet and HttpPost). You can check it yourself on GitHub . (See SelectBestCandidate method)

Theoretically if parameters matters the logic to choose between actions based on parameters should be in SelectBestActions method, but it ignores parameters.

In you case good option seems to be to have just 1 method:

public IActionResult ReportDetails(int? reportId, bool? approved) {
    ....
}

and then check if approved is NULL ( /Report/ReportDetails?reportId=7 ), then implement 1st logic, otherwise( /Report/ReportDetails?reportId=7&approved=True ) implement 2nd logic. If logic contains many lines you can extract them in new method and call it.

public IActionResult ReportDetails(int? reportId, bool? approved) {
     if (approved != null)
     {
        //implement logic for 2nd case(approved=True)
     }
     //implement logic for 1st case (just reportId=7)
}

Answer 4

You could use RouteAttribute

[Route("ReportDetails/{reportId}")]
public IActionResult ReportDetails(int? reportId){
....
[Route("ReportDetails/{reportId}/{approved}")]
public IActionResult ReportDetails(int? reportId, bool ? approved) {
....

Your URLs would then be;

/Report/ReportDetails/7 for the first and

/Report/ReportDetails/7/True for second

This will work with the default startup.cs

app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });