Routing In MVC Application(Types And Implementation Methods )

Introduction

This article will summarize adjusting routing configurations in an MVC project
The aim of the adjustments was to trace a problem that a certain action was hit multiple times
The problem had nothing to do with routing, but I investigated routing configuration in my search for the cause

The rest of the article will describe different types of routing supported and the configurations needed in the levels of,

Application execution pipeline (middleware)
The controllers and action

Definitions

Routing is responsible for matching incoming HTTP requests and dispatching those requests to the app's executable endpoints
Endpoints are the app's units of executable request-handling code. Endpoints are defined in the app and configured when the app starts

Types of routing

Conventional Based Routing

It is the basic routing type implemented by default.
You will find the middleware pipeline configured to implement this type through the following code in the startup.cs.
```
app.UseEndpoints(endpoints => {
    endpoints.MapControllerRoute(name: "default", pattern: "{controller=Home}/{action=Index}/{id?}");
})
```
The HTTP request with a URL of format /Home/Index or Home/Index/1 will be processed by the action method Index n Home Controller or By Z Action method in the Y controller if the URL was http://abc.com/Y/Z.

Area Conventional Based Routing

Areas provide a way to partition an ASP.NET Core Web app into smaller functional groups
Each group has its own set of Razor Pages, controllers, views, and models

Controller level

Routing In MVC Application

View Level

Routing In MVC Application

Application execution pipeline can be configured to enable area-based routing in either one of the following two ways.

Using a code similar to the previous one as follows,

endpoints.MapControllerRoute(name: "Area", pattern: "{area:exists}/{controller=Home}/{action=Index}/{id?}", defaults: new {
    area = "Home"
});

Using MapAreaControllerRoute method IEndpointRouteBuilderInterface as in the following example,

endpoints.MapAreaControllerRoute(pattern: "{area}/{controller}/{action}/{id?}", name: "areas", areaName: "Home", defaults: new {
    controller = "Home", action = "Index"
});

Mixed Conventional Based Routing

In Mixed Conventional Based Routing
The URL specified in the HTTP request is checked against the patterns specified in both routing types
Default routing is determined by finding a match against the patterns specified in each routing type in order

Attribute routing

Hopefully, we will discuss this in a later article.

Examples

Default routing type (conventional without area support).

configuration in the startup.cs

app.UseEndpoints(endpoints => {
    endpoints.MapControllerRoute(name: "default", pattern: "{controller=Home}/{action=Index}/{id?}");
})

Result

Routing In MVC Application

Conventional with area support

Configuration in the startup.cs either,

endpoints.MapAreaControllerRoute(pattern: "{area}/{controller}/{action}/{id?}", name: "areas", areaName: "Home", defaults: new {
    controller = "Home", action = "Index"
});

or,

endpoints.MapControllerRoute(name: "Area", pattern: "{area:exists}/{controller=Home}/{action=Index}/{id?}", defaults: new {
    area = "Home"
});

Result

Routing In MVC Application

Mixed conventional

Example 1 - configuration

endpoints.MapControllerRoute(name: "default", pattern: "{controller=Home}/{action=Index}/{id?}");
endpoints.MapAreaControllerRoute(pattern: "{area}/{controller}/{action}/{id?}", name: "areas", areaName: "Home", defaults: new {
    controller = "Home", action = "Index"
});

Result

Routing In MVC Application

Example 2 - Configuration

endpoints.MapAreaControllerRoute(pattern: "{area}/{controller}/{action}/{id?}", name: "areas", areaName: "Home", defaults: new {
    controller = "Home", action = "Index"
});
endpoints.MapControllerRoute(name: "default", pattern: "{controller=Home}/{action=Index}/{id?}");

Result

Routing In MVC Application

Redirecting from an action in a controller not belonging to an area to an action belonging to an area.

From Controller this will work only if area conventional routing comes first in the startup.cs file as follows,

endpoints.MapAreaControllerRoute(pattern: "{area}/{controller}/{action}/{id?}", name: "areas", areaName: "Home", defaults: new {
    controller = "Home", action = "Index"
});
endpoints.MapControllerRoute(name: "default", pattern: "{controller=Home}/{action=Index}/{id?}");

Otherwise, errors of too many directions will occur.

Routing In MVC Application

Through a hyperlink.

Example

Routing In MVC Application

Result

Routing In MVC Application

Conclusion

This article summarized different conventional routing implementation methods as well as ways to navigate between routes.

Resources

https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/routing?view=aspnetcore-5.0#cr
https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/areas?view=aspnetcore-5.0
https://stackoverflow.com/questions/60038265/redirecttoaction-where-the-controller-is-in-an-area