Viacheslav Eremin | Processing absent files by custom middleware

(CORE) CORE (2022)

Processing absent files by custom middleware

Middleware is new term for ASP.NET Core, at common this is ordinary Handler like this Как сделать простейший Web-handler - формирующий XML или JSON., but in Net Core it can be perform as function in App.Use.

In current project I have a lot of various Roots, see Asp Net Core Routing, Conventions, DefultUI. Site roots - ContentRootPath/StaticFilesRoot/WebRootPath/WebRootFileProvider/RazorPagesOptions.RootDirectory., by this approach I have redirect any request to another file and can make custom processing to any missing files (custom code, header or anything else).

 254:          'Route anylizer

 255:          App.Use(Async Function(context As HttpContext, NextRequestDelegate As RequestDelegate)

 256:                      Dim CurrentEndpoint = context.GetEndpoint()

 257:                      If (CurrentEndpoint Is Nothing) Then

 258:                          Debug.WriteLine($"RequestPath {context.Request.Path} endpoint nothing.")

 259:                          Dim StaticOptions As StaticFileOptions = New StaticFileOptions With {.FileProvider = New PhysicalFileProvider(Builder.Configuration("StaticFilesRoot"))}

 260:                          Dim Opt As IOptions(Of StaticFileOptions) = Options.Create(StaticOptions)

 261:                          Dim NewEnvironment As IWebHostEnvironment = Environment

 262:                          NewEnvironment.ContentRootPath = Builder.Configuration("StaticFilesRoot")

 263:                          NewEnvironment.WebRootPath = Builder.Configuration("StaticFilesRoot")

 264:                          Dim StaticMiddleware = New StaticFileMiddleware(

 265:                              Async Function()

 266:                                  'Await NextRequestDelegate(context)

 267:                                  Dim StaticFile As IFileInfo = Opt.Value.FileProvider.GetFileInfo(context.Request.Path)

 268:                                  If Not StaticFile.Exists Then

 269:                                      Await context.Response.WriteAsync("File is nothing")

 270:                                  Else

 271:                                      Await context.Response.SendFileAsync(StaticFile)

 272:                                  End If

 273:

 274:                              End Function,

 275:                              NewEnvironment,

 276:                              Opt,

 277:                              LoggerFactory)

 278:                          Await StaticMiddleware.Invoke(context)

 279:                      Else

 280:                          Debug.WriteLine($"Endpoint: {CurrentEndpoint.DisplayName}")

 281:                          Dim Endpoint As RouteEndpoint = TryCast(CurrentEndpoint, RouteEndpoint)

 282:                          Debug.WriteLine($"RoutePattern: {Endpoint?.RoutePattern.RawText}")

 283:                          For j As Integer = 0 To CurrentEndpoint.Metadata.Count - 1

 284:                              Debug.WriteLine($"Endpoint Metadata {j}: {CurrentEndpoint.Metadata(j)}")

 285:                          Next

 286:                          Await NextRequestDelegate(context)

 287:                      End If

 288:                  End Function)

 289:

We also can use middlware to handle unexpected exception, like we doing that in desktop application Trap unhandled exception in windows application.. This is a pattern.

Comments (

)

<00> <01> <02> <03> <04> <05> <06> <07> <08> <09> <10> <11> <12> <13> <14> <15> <16> <17> <18> <19> <20> <21> <22> <23>

Link to this page: http://www.vb-net.com/StaticMiddleware/Index.htm