EF Razor Pages example with net framework

- updated a bunch of sections, add more info, make readable

net-core-hello-entity-framework-database-sql.md
- keep intro contents for this one
- add non SQLite versions

input/posts/net-core-hello-entity-framework-database-sql.md

@@ -1,14 +1,15 @@
-Title: dotnet core Hello World with Entity Framework and Database
+Title: dotnet core Hello World with Entity Framework and Database in 2018
 Published: 7/1/2018
 Tags:
   - dotnet core
   - entity framework
 ---
+Before we show how to create MVC app with entity framework we show how to create a simple console app.
 
 ## Creating a hello world console application
 With .net core things are pretty simple. We run two commands and it does everything we need for a hello world program,
 
-    $ dotnet new console -n P1_Console
+    $ dotnet new console -n P1_ConsoleApp
 
 It creates the directory and puts required hello world source file and project file inside the dir named 'P1_Console'. What type of applications does it support can be found at [microsoft docs - dotnet-new][4]
 

input/posts/net-core-mvc_hello-entity-framework_2021-08.md

@@ -0,0 +1,127 @@
+Title: dotnet core Hello World with Entity Framework and Database
+Published: 8/12/2021
+Tags:
+  - dotnet core
+  - entity framework
+---
+
+## Razor Pages App
+We follow this primary reference documentation, [MS Docs - aspnet/core/data/ef-rp/intro](https://docs.microsoft.com/en-us/aspnet/core/data/ef-rp/intro)
+
+    dotnet new webapp -n P03_ContosoUniversity_RP
+    cd P03_ContosoUniversity_RP
+
+    dotnet add package Microsoft.VisualStudio.Web.CodeGeneration.Design
+    dotnet add package Microsoft.EntityFrameworkCore.SQLite
+    dotnet add package Microsoft.EntityFrameworkCore.SqlServer
+    dotnet add package Microsoft.EntityFrameworkCore.Design
+    dotnet add package Microsoft.EntityFrameworkCore.Tools
+
+    dotnet add package Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore
+
+    dotnet aspnet-codegenerator razorpage -m Student -dc ContosoUniversity.Data.SchoolContext `
+    -udl -outDir Pages\Students --referenceScriptLibraries
+
+If we are using SQLite database,
+
+    dotnet aspnet-codegenerator razorpage -m Student -dc ContosoUniversity.Data.SchoolContext `
+    -udl -outDir Pages\Students --referenceScriptLibraries -sqlite
+
+
+We refactor all `P03_ContosoUniversity_RP` with `ContosoUniversity`.
+
+Scaffolding source files have `context.Student` which is not correct. We update those with `context.Students`.
+
+    dotnet tool update --global dotnet-ef
+    dotnet ef database update
+
+EF supports dev environment as well,
+
+    dotnet ef database update -- --environment Development
+
+Finally, we run it,
+
+    $Env:ASPNETCORE_ENVIRONMENT = "Development"
+    dotnet run
+
+There's some differences with the cu50 sample.
+- `Pages\Students\Index.cshtml.cs` is much larger not just one line,
+
+    Student = await _context.Students.ToListAsync();
+
+- Indentations under `Data` folder
+- Code for Error messages, logger etc in a number of files
+- they have some region definitions with snippet names
+
+In summary, the actual cu50 sample is much more complete than the one we create by following the tutorial.
+
+Some observations,
+- localdb mdf files are usually stored at `$HOME` (for example, `C:\Users\YOUR_NAME`)
+
+### References
+**Refs on Razor Pages**
+- [Razor Pages](https://docs.microsoft.com/en-us/aspnet/core/razor-pages)
+- [learnrazorpages - Handler Methods in Razor Pages](https://www.learnrazorpages.com/razor-pages/handler-methods)
+
+**Refs on Entity Framework Performance**
+- [Common performance mistakes](https://medium.com/swlh/entity-framework-common-performance-mistakes-cdb8861cf0e7)
+
+
+**Example to connect from Visual Studio Server Explorer**
+
+    Server Name: (LocalDb)\MSSQLLocalDB
+    DB: CU-1
+
+ref: 1. [connection strings example](https://docs.microsoft.com/en-us/aspnet/mvc/overview/getting-started/introduction/creating-a-connection-string), 2. [how to connect database in visual studio data explorer](https://stackoverflow.com/questions/21563940/how-to-connect-to-localdb-in-visual-studio-server-explorer)
+
+
+## MVC App
+Steps
+
+    dotnet new mvc -n P03_ContosoUniversity
+
+Replace `P03_ContosoUniversity` with 'Contoso University'.
+
+    dotnet add package Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore
+
+Primary reference documentation, [MS Docs - aspnet/core/data/ef-mvc/intro](https://docs.microsoft.com/en-us/aspnet/core/data/ef-mvc/intro)
+
+We add default connection in `appsettings.Development.json`. We pretty much follow the steps in tutorial and able to produce working version. Only, using VS Code instead of Visual Studio Pro is bit of work since all CLI commands are not provided and we need to repro them, especially scaffolding ones.
+
+## Razor Pages App (net core)
+This is an experiment to run the EF Core Razor App with .net core,
+
+We update net framework target in `.csproj` file.
+
+We add following nuget packages,
+
+    dotnet new webapp -n P03_ContosoUniversity_netcore
+    dotnet add package Microsoft.EntityFrameworkCore.Design
+    dotnet add package Microsoft.EntityFrameworkCore
+    dotnet add package Microsoft.EntityFrameworkCore.SQLite
+
+
+We add all the scaffolding files from previous project (above) that targets .net6
+
+We end up finding that the following method calls:
+
+    // in ConfigureServices
+    // services.AddDatabaseDeveloperPageExceptionFilter();
+    // in Configure
+    // app.UseMigrationsEndPoint();
+
+require `Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore` package,
+
+    dotnet add package Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore
+    Determining projects to restore...
+    Writing C:\Users\atiq\AppData\Local\Temp\tmp6CF5.tmp
+    info : Adding PackageReference for package 'Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore' into project 'D:\Code\CS\P03_ContosoUniversity_netcore\P03_ContosoUniversity_netcore.csproj'.
+    info :   GET https://api.nuget.org/v3/registration5-gz-semver2/microsoft.aspnetcore.diagnostics.entityframeworkcore/index.json
+    info :   OK https://api.nuget.org/v3/registration5-gz-semver2/microsoft.aspnetcore.diagnostics.entityframeworkcore/index.json 419ms
+    info : Restoring packages for D:\Code\CS\P03_ContosoUniversity_netcore\P03_ContosoUniversity_netcore.csproj...
+    error: NU1202: Package Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore 5.0.9 is not compatible with netcoreapp3.1 (.NETCoreApp,Version=v3.1). Package Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore 5.0.9 supports: net5.0 (.NETCoreApp,Version=v5.0)
+    error: Package 'Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore' is incompatible with 'all' frameworks in project 'D:\Code\CS\P03_ContosoUniversity_netcore\P03_ContosoUniversity_netcore.csproj'
+
+Also, the old version (3.1.18 supports .net core) of `Diagnostics.EntityFrameworkCore` doesn't have the definitions mentioned above.
+
+Conclusion: since some of the packages i.e., `Diagnostics.EntityFrameworkCore` don't target .net core and only targets newer versions of net framework, for example, .net 6. We cannot run the examples from official tutorial that uses EF Core or Diagnostics (may be Logging package as well).