A Step-by-Step Guide to Migrating a Project from ASP.NET MVC to ASP.NET Core

Step-by-step guide Here is a practical guide on migrating a project from ASP.NET MVC framework to ASP.NET Core. Step-by-step instruction written by the team of can be easily applied to any ASP.NET MVC project. nopCommerce open-source project It also describes why you might need to upgrade, and why projects that do not yet keep up with pace should consider it. Why porting to ASP.NET Core? Before proceeding to the steps of porting from ASP.NET MVC to ASP.NET Core (using nopCommerce as an example), let's take the quick overview of this framework advantages. ASP.NET Core is already a fairly well-known and developed framework with several major updates making it quite stable, technologically advanced and resistant to XSRF/CSRF attacks. Cross-platform is one of the distinguishing features making it more and more popular. From now on, your web application can run both in Windows and Unix environment. Modular architecture - ASP.NET Core comes fully in the form of NuGet packages, it allows optimizing the application, including the selected required packages. This improves solution performance and reduces the time it takes to upgrade separate parts. This is the second important characteristic that allows developers to integrate new features into their solution more flexible. Performance is another step towards building a high-performance application. ASP.NET Core handles 2.300% more requests per second than ASP.NET 4.6, and 800% more requests per second than node.js. You can check the detailed performance tests yourself or . here here Middleware is a new light and fast modular pipeline for in-app requests. Each part of middleware processes an HTTP request, and then either decides to return the result or passes the next part of middleware. Best plaintext responses per second, Test environment This approach gives the developer full control over the HTTP pipeline and contributes to the development of simple modules for the application, which is important for a growing open-source project. Also, ASP.NET Core MVC provides features that simplify web development. nopCommerce already used some of them, such as the Model-View-Controller template, Razor syntax, model binding, and validation. Among the new features are: Tag Helpers. Server-part code for participation in creating and rendering HTML elements in Razor files. View components. A new tool, similar to partial views, but of much higher performance. nopCommerce uses view components when reusing rendering logic is required and the task is too complex for partial view. DI in views. Although most of the data displayed in views comes from the controller, nopCommerce also has views where dependency injection is more convenient. Of course, ASP.NET Core has much more features, we viewed the most interesting ones only. Now let's consider the points to keep in mind when porting your app to a new framework. Migration The following descriptions contains large amount of links to the official ASP.NET Core documentation to give more detailed information about the topic and guide developers who face such a task the first time. Step 1. Preparing a toolkit The first thing you need is to upgrade Visual Studio 2017 to version 15.3 or later and install the latest version of .NET Core SDK. Before porting, we advise to use . This can be a good starting point to understand how labor-intensive porting from one platform to another will be. Nevertheless, this tool does not cover all the issues, this process has many pitfalls to be solved as they emerge. .Net Portability Analyzer Below we will describe the main steps and the solutions used in nopCommerce project. The first and the easiest thing to do is to update links to the libraries used in the project so to they support .NET Standard. Step 2. NuGet package compatibility analysis to support .Net standard If you use NuGet packages in your project, check whether they are compatible with .NET Core. One way to do this is to use the tool. NuGetPackageExplorer Step 3. The new format of csproj file in .NET Core A new approach for adding references to third-party packages was introduced in .NET Core. When adding a new class library, you need to open the main project file and replace its contents as follows: netcoreapp2.2 ... ... Project Sdk "Microsoft.NET.Sdk" PropertyGroup TargetFramework TargetFramework PropertyGroup ItemGroup PackageReference Include "Microsoft.AspNetCore.App" Version "2.2.6" ItemGroup Project References to the connected libraries will be loaded automatically. For more information on comparing the project.json and CSPROJ properties, read the official documentation here and here. Step 4. Namespace update Delete all uses of System.Web and replace them with Microsoft.AspNetCore. Step 5. Configure the Startup.cs file instead of using global.asax ASP.NET Core has a new way of loading the app. The app entry point is , and there is no dependency on the Global.asax file. registers the middlewares in the app. must include the method. The required middleware should be added to the pipeline in . Startup Startup Startup Configure Configure Issues to solve in Startup.cs: Configuring middleware for MVC and WebAPI requests Configuring for: . You will inevitably face various collisions during porting, thus be ready and set up exception handling in the development . With , we add middleware to catch exceptions. Exception handling environment UseDeveloperExceptionPage . has also been changed. IRouteBuilder is now used instead of RouteCollection, as a new way (IActionConstraint) MVC routing Registration of new routes to register restrictions The filters should be updated in accordance with . MVC/WebAPI filters. the new implementation of ASP.NET Core MVC/ WebAPI Formatters Binding models mvcBuilder = services.AddMvc(); mvcBuilder.AddMvcOptions(options => options.ModelBinderProviders.Insert( , NopModelBinderProvider())); //add basic MVC feature var //add custom model binder provider (to the top of the provider list) 0 new : { { (context == ) ArgumentNullException( (context)); modelType = context.Metadata.ModelType; (! (BaseNopModel).IsAssignableFrom(modelType)) ; (context.Metadata.IsComplexType && !context.Metadata.IsCollectionType) { propertyBinders = context.Metadata.Properties .ToDictionary(modelProperty => modelProperty, modelProperty => context.CreateBinder(modelProperty)); NopModelBinder(propertyBinders, EngineContext.Current.Resolve ()); } ; } } /// Represents model binder provider for the creating NopModelBinder /// /// public class NopModelBinderProvider IModelBinderProvider /// Creates a nop model binder based on passed context /// /// Model binder provider context /// Model binder /// IModelBinder ( ) public GetBinder ModelBinderProviderContext context if null throw new nameof var if typeof return null //use NopModelBinder as a ComplexTypeModelBinder for BaseNopModel if //create binders for all model properties var return new //or return null to further search for a suitable binder return null . To include Area in an ASP.NET Core app, add a regular route to the Startup.cs file. For example, this way it will look for configuring Admin/ area Areas app.UseMvc(routes => { routes.MapRoute( , ); routes.MapRoute( name: , template: ); }); "areaRoute" "{area:exists}/{controller=Admin}/{action=Index}/{id?}" "default" "{controller=Home}/{action=Index}/{id?}" When doing it, the folder with the name Area with the Admin folder inside, should be in the app root. Now the attribute will be used to connect the controller with this area. [Area("Admin")] [Route("admin")]. It remains only to create views for all the actions described in the controller. [ ] [ ] : { { View(); } } Area( ) "Admin" Route( ) "admin" public class AdminController Controller IActionResult ( ) public Index return Validation IFormCollection should not be passed to the controllers since in this case, asp.net server validation is disabled - MVC is suppressing further validation if the IFormCollection is found to be not null. To solve the problem, this property might be added to the model, this will prevent us from passing directly to the controller method. This rule works only if a model is available, if there is no model, there will be no validation. Child properties are no longer automatically validated and should be specified manually. Step 6. Migrate HTTP handlers and HttpModules to Middleware HTTP handlers and HTTP modules are in fact very similar to the concept of , but unlike modules, the middleware order is based on the order in which they are inserted into the request pipeline. The order of modules is mainly based on the events of The order of middleware for responses is opposite to the order for requests, while the order of modules for requests and responses is the same. Knowing this, you can proceed with the update. Middleware in ASP.NET Core application life cycle. What should be updated: Migration of modules for Middleware (AuthenticationMiddleware, CultureMiddleware, etc.) to Middleware Handlers Use of new middleware Authentication in nopCommerce does not use a built-in authentication system; for this purpose, AuthenticationMiddleware developed in accordance with the new ASP.NET Core structure is used. { RequestDelegate _next; { Schemes = schemes ?? ArgumentNullException( (schemes)); _next = next ?? ArgumentNullException( (next)); } IAuthenticationSchemeProvider Schemes { ; ; } { context.Features.Set ( AuthenticationFeature { OriginalPath = context.Request.Path, OriginalPathBase = context.Request.PathBase }); handlers = context.RequestServices.GetRequiredService (); ( scheme Schemes.GetRequestHandlerSchemesAsync()) { { ( handlers.GetHandlerAsync(context, scheme.Name) IAuthenticationRequestHandler handler && handler.HandleRequestAsync()) ; } { } } defaultAuthenticate = Schemes.GetDefaultAuthenticateSchemeAsync(); (defaultAuthenticate != ) { result = context.AuthenticateAsync(defaultAuthenticate.Name); (result?.Principal != ) { context.User = result.Principal; } } _next(context); } } public class AuthenticationMiddleware private readonly ( ) public AuthenticationMiddleware IAuthenticationSchemeProvider schemes, RequestDelegate next throw new nameof throw new nameof public get set Task ( ) public async Invoke HttpContext context new var foreach var in await try if await is await return catch // ignored var await if null var await if null await ASP.NET provides a lot of built-in middleware that you can use in your application, but the developer can also and add it to HTTP request pipeline. create his own middleware To simplify this process, we added a special interface to nopCommerce, and now it’s enough to just create a class that implements it. { ; ; Order { ; } } public interface INopStartup /// Add and configure any of the middleware /// /// Collection of service descriptors /// Configuration of the application /// ( ) void ConfigureServices IServiceCollection services, IConfiguration configuration /// Configure the using of added middleware /// /// Builder for configuring an application's request pipeline /// ( ) void Configure IApplicationBuilder application /// Gets order of this startup configuration implementation /// /// int get Here you can add and configure your middleware: : { { services.AddNopDataProtection(); services.AddNopAuthentication(); } { application.UseNopAuthentication(); } Order => ; } /// Represents object for the configuring authentication middleware on application startup /// /// public class AuthenticationStartup INopStartup /// Add and configure any of the middleware /// /// Collection of service descriptors /// Configuration of the application /// ( ) public void ConfigureServices IServiceCollection services, IConfiguration configuration //add data protection //add authentication /// Configure the using of added middleware /// /// Builder for configuring an application's request pipeline /// ( ) public void Configure IApplicationBuilder application //configure authentication /// Gets order of this startup configuration implementation /// /// public int 500 //authentication should be loaded before MVC Step 7. Using built-in DI injection is one of the key features when designing an app in ASP.NET Core. You can develop loosely coupled applications that are more testable, modular and as a result more maintainable. This was made possible by following the principle of dependency inversion. Dependency To inject dependencies, we used IoC (Inversion of Control) containers. In ASP.NET Core, such a container is represented by the IServiceProvider interface. Services are installed in the app in the Startup.ConfigureServices() method. Any registered service can be configured with three scopes: transient scoped singleton services.AddDbContext (options => options.UseSqlServer(Configuration.GetConnectionString( ))); services.AddSingleton (); "DefaultConnection" Step 8. Using WebAPI project compatibility shells (Shim) To simplify migration of an existing Web API, we advise using the NuGet package . It supports the following : Microsoft.AspNetCore.Mvc.WebApiCompatShim compatible features Adding ApiController type; Enabling web API style model binding; Extending model binding so that controller actions can accept HttpRequestMessage type parameters; Adding message formatters enabling actions to return results of HttpResponseMessage type. services.AddMvc().AddWebApiConventions();

routes.MapWebApiRoute(name: , template: ); "DefaultApi" "api/{controller}/{id?}" Step 9. Porting Application Configuration Some settings were previously saved in the web.config file. Now we use based on the key-value pairs set by . This is the recommended method in ASP.NET Core, and we use the appsettings.json file. a new approach configuration providers You can also use the NuGet package if for some reason you want to continue using *.config. In this case, the app cannot run on Unix platforms, but on IIS only. System.Configuration.ConfigurationManager If you want to use the Azure key storage configuration provider, then you need to refer to . Our project did not contain such a task. Migrating content to Azure Key Vault Step 10. Porting static content to wwwroot To serve , specify to web host the content root of the current directory. The default is wwwroot. You can configure your folder for storing static files by setting up middleware. static content Step 11. Porting EntityFramework to EF Core If the project uses some specific , that are in EF Core, it makes sense to run the application on the NET Framework. Though in this case, we will have to reject the multi-platform feature, and the application will run on Windows and IIS only. features of Entity Framework 6 not supported Below are the main changes to be considered: System.Data.Entity namespace is replaced by Microsoft.EntityFrameworkCore; The signature of the DbContext constructor has been changed. Now you should inject DbContextOptions; HasDatabaseGeneratedOption(DatabaseGeneratedOption.None) method is replaced by ValueGeneratedNever(); WillCascadeOnDelete(false) method is replaced by OnDelete (DeleteBehavior.Restrict); OnModelCreating(DbModelBuilder modelBuilder) method is replaced by OnModelCreating(ModelBuilder modelBuilder); HasOptional method is no longer available; Object configuration is changed, now OnModelCreating is using since EntityTypeConfiguration is no longer available; ComplexType attribute is no longer available; IDbSet interface is replaced by DbSet; ComplexType - complex type support appeared in EF Core 2 with the type, and tables without Primary Key with in EF Core 2.1; Owned Entity QueryType External keys in EF Core generate using the [Entity]Id template, unlike EF6, that uses the [Entity]_Id template. Therefore, add external keys as a regular property to the entity first; shadow properties To support DI for DbContext, configure your DbContex in ConfigureServices. { services.AddDbContextPool (optionsBuilder => { optionsBuilder.UseSqlServerWithLazyLoading(services); }); } { nopConfig = services.BuildServiceProvider().GetRequiredService (); dataSettings = DataSettingsManager.LoadSettings(); (!dataSettings?.IsValid ?? ) ; dbContextOptionsBuilder = optionsBuilder.UseLazyLoadingProxies(); (nopConfig.UseRowNumberForPaging) dbContextOptionsBuilder.UseSqlServer(dataSettings.DataConnectionString, option => option.UseRowNumberForPaging()); dbContextOptionsBuilder.UseSqlServer(dataSettings.DataConnectionString); } /// Register base object context /// /// Collection of service descriptors /// ( ) public static void AddNopObjectContext IServiceCollection services this /// SQL Server specific extension method for Microsoft.EntityFrameworkCore.DbContextOptionsBuilder /// /// Database context options builder /// Collection of service descriptors /// ( ) public static void UseSqlServerWithLazyLoading DbContextOptionsBuilder optionsBuilder, IServiceCollection services this var var if true return var if else To verify that EF Core generates a similar database structure as Entity Framework when , use the tool. migrating SQL Compare Step 12. Removing all HttpContext references and replacing obsolete classes and changing the namespace During the project migration, you will find that a sufficiently large number of classes have been renamed or moved, and now you should comply with the new requirements. Here is a list of the main changes you may encounter: HttpPostedFileBase 🡪 FormFile Access HttpContext can now be accessed via IHttpContextAccessor HtmlHelper 🡪 HtmlHelper ActionResult 🡪 ActionResult HttpUtility 🡪 WebUtility ISession instead of HttpSessionStateBase accessible from HttpContext.Session. from Microsoft.AspNetCore.Http Request.Cookies returns IRequestCookieCollection: IEnumerable >, then instead of HttpCookie we use KeyValuePair from Microsoft.AspNetCore.Http Namespace replacement: SelectList 🡪 Microsoft.AspNetCore.Mvc.Rendering UrlHelper 🡪 WebUtitlity MimeMapping 🡪 FileExtensionContentTypeProvider MvcHtmlString 🡪 IHtmlString and HtmlString ModelState, ModelStateDictionary, ModelError 🡪 Microsoft.AspNetCore.Mvc.ModelBinding FormCollection 🡪 IFormCollection Request.Url.Scheme 🡪 this.Url.ActionContext.HttpContext.Request.Scheme Other: MvcHtmlString.IsNullOrEmpty(IHtmlString) 🡪 String.IsNullOrEmpty(variable.ToHtmlString()) [ValidateInput (false)] - does not exist anymore and is no longer needed HttpUnauthorizedResult 🡪 UnauthorizedResult [AllowHtml] - directive does not exist anymore and is no longer needed TagBuilder.SetInnerText method is replaced by InnerHtml.AppendHtml JsonRequestBehavior.AllowGet when returning Json is no longer needed HttpUtility.JavaScriptStringEncode. JavaScriptEncoder.Default.Encode Request.RawUrl. Request.Path + Request.QueryString should be separately connected AllowHtmlAttribute - class no longer exists XmlDownloadResult - now you can use just return File(Encoding.UTF8.GetBytes (xml), "application / xml", "filename.xml"); [ValidateInput(false)] - directive does not exist anymore and is no longer needed Step 13. Authentication and authorization update As was already mentioned above, nopCommerce project does not involve the built-in authentication system, it is implemented in a separate middleware layer. However, ASP.NET Core has its own system for credentials providing. You can view the documentation to know about them in details. As for data protection, we no longer use . Instead, we use the built-in data protection feature. By default, keys are generated when the application starts. As the data storage can be: MachineKey File system - file system-based keystore Azure Storage - data protection keys in Azure BLOB object storage Redis - data protection keys in the Redis cache Registry - used if the application does not have access to the file system EF Core - keys are stored in the database If the built-in providers are not suitable, you can specify your own key storage provider by making a custom . IXmlRepository Step 14. JS/CSS update The way of using static resources has changed, now they should all be stored in the root folder of the project , unless other settings are made. wwwroot When using javascript built-in blocks, we recommend moving them to the end of the page. Just use the asp-location = "Footer" attribute for your tags. The same rule applies to js files. Use the extension as a replacement for System.Web.Optimization - this will enable bundling and minification. JavaScript and CSS while building the project ( ). BundlerMinifier view the documentation Step 15. Porting views First of all, Child Actions are no longer used, instead, ASP.NET Core suggests using a new high-performance tool - called asynchronously. ViewComponents How to get a string from ViewComponent: { ( .IsNullOrEmpty(componentName)) ArgumentNullException( (componentName)); actionContextAccessor = HttpContext.RequestServices.GetService( (IActionContextAccessor)) IActionContextAccessor; (actionContextAccessor == ) Exception( ); context = actionContextAccessor.ActionContext; viewComponentResult = ViewComponent(componentName, arguments); viewData = ViewData; (viewData == ) { NotImplementedException(); } tempData = TempData; (tempData == ) { NotImplementedException(); } ( writer = StringWriter()) { viewContext = ViewContext( context, NullView.Instance, viewData, tempData, writer, HtmlHelperOptions()); viewComponentHelper = context.HttpContext.RequestServices.GetRequiredService (); (viewComponentHelper IViewContextAware)?.Contextualize(viewContext); result = viewComponentResult.ViewComponentType == ? viewComponentHelper.InvokeAsync(viewComponentResult.ViewComponentName, viewComponentResult.Arguments): viewComponentHelper.InvokeAsync(viewComponentResult.ViewComponentType, viewComponentResult.Arguments);

result.Result.WriteTo(writer, HtmlEncoder.Default); writer.ToString(); } } /// Render component to string /// /// Component name /// Arguments /// Result /// ( ) protected virtual string RenderViewComponentToString componentName, arguments = string object null if string throw new nameof var typeof as if null throw new "IActionContextAccessor cannot be resolved" var var var if null throw new var if null throw new using var new var new new // IViewComponentHelper is stateful, we want to make sure to retrieve it every time we need it. var as var null return Note that there is no need to use HtmlHelper anymore, ASP.NET Core includes many auxiliary built-in . When the application is running, the Razor engine handles them on the server and ultimately converts to standard html elements. Tag Helpers This makes application development a whole lot easier. And of course, you can implement your own tag helpers. We started using dependency injection in views instead of enabling settings and services using EngineContext. So, the main points on porting views are as follows: Convert Views/web.config to Views/_ViewImports.cshtml - to import namespaces and inject dependencies. This file does not support other Razor features, such as function and section definitions Convert namespaces.add to @using Porting any settings to the main application configuration Scripts.Render and Styles.Render do not exist. Replace with links to output data of libman or BundlerMinifier Conclusion The process of migrating a large web application is a very time-consuming task which, as a rule, cannot be carried out without the pitfalls. We planned to migrate to a new framework as soon as its first stable version was released but were not able to make it right away, as there were some critical features that had not been transferred to .NET Core, in particular, those related to EntityFramework. Therefore, we had first to make our release using a mixed approach - the .NET Core architecture with the .NET Framework dependencies, which in itself is a unique solution. Being first is not easy, but we are sure we’ve made the right choice, and our huge community supported us in this. We were able to fully adapt our project after the release of .NET Core 2.1, having by that time a stable solution already working on the new architecture. It remained only to replace some packages and rewrite the work with EF Core. Thus, it took us several months and two released versions to completely migrate to the new framework. We can say with confidence that we are the to carry out such a migration. In this guide, we tried to put together the entire migration process in a structured form and describe various bottlenecks so that other developers could rely on this material and follow the roadmap when solving the same task. first large project