adding a readme for blazor identity for scenario specific information. (#2999)

* adding a readme for blazor identity for scenario specific information.

* PR suggestions added.

* updated to fwlink

src/Scaffolding/VS.Web.CG.Mvc/BlazorIdentity/BlazorIdentityGenerator.cs

@@ -141,9 +141,18 @@ namespace Microsoft.VisualStudio.Web.CodeGenerators.Mvc.Blazor
 
             var blazorTemplateModel = await ValidateAndBuild(model);
             ExecuteTemplates(blazorTemplateModel);
+            AddReadmeFile(blazorTemplateModel.BaseOutputPath);
             await ModifyFilesAsync(blazorTemplateModel);
         }
 
+        internal void AddReadmeFile(string outputPath)
+        {
+            string fileName = BlazorIdentityHelper.BlazorIdentityReadmeFileName;
+            string readmeFilePath = Path.Combine(outputPath, fileName);
+            FileSystem.WriteAllText(readmeFilePath, BlazorIdentityHelper.BlazorIdentityReadmeString);
+            Logger.LogMessage($"Added Blazor identity file : {fileName}");
+        }
+
         internal async Task<BlazorIdentityModel> ValidateAndBuild(BlazorIdentityCommandLineModel commandlineModel)
         {
             commandlineModel.DatabaseProvider = ModelMetadataUtilities.ValidateDatabaseProvider(commandlineModel.DatabaseProviderString, Logger, isIdentity: true);

src/Scaffolding/VS.Web.CG.Mvc/BlazorIdentity/BlazorIdentityHelper.cs

@@ -101,5 +101,23 @@ namespace Microsoft.VisualStudio.Web.CodeGenerators.Mvc.BlazorIdentity
 
             return filteredChanges;
         }
+
+        internal static string BlazorIdentityReadmeFileName = "Scaffolding-README.md";
+        internal static string BlazorIdentityReadmeString =
+@"Blazor Identity scaffolding has completed successfully.
+
+For setup and configuration information, see https://go.microsoft.com/fwlink/?linkid=2290075.
+
+If the project had identity support prior to scaffolding, ensure that the following changes are present in Program.cs:
+1. Correct DbContextClass is used in the following statements :
+    - var connectionString = builder.Configuration.GetConnectionString(DBCONTEXT_CONNECTIONSTRING) ...
+    - builder.Services.AddDbContext<DBCONTEXT>(options => ...
+    - builder.Services.AddIdentityCore<IDENTITY_USER_CLASS>...
+        .AddEntityFrameworkStores<DBCONTEXT>() ...
+2. Correct Identity User class is being used, (if using the default 'IdentityUser' or a custom IdentityUser class).
+    - builder.Services.AddIdentityCore<IDENTITY_USER_CLASS>...
+    - builder.Services.AddSingleton<IEmailSender<IDENTITY_USER_CLASS>...
+";
+
     }
 }