dotnet core Hello World with Entity Framework and Database

Published on Thursday, 12 August 2021

Razor Pages App

We follow this primary reference documentation, MS Docs - 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,

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)


Refs on Razor Pages

Refs on Entity Framework Performance

Example to connect from Visual Studio Server Explorer

Server Name: (LocalDb)\MSSQLLocalDB
DB: CU-1

ref: 1. connection strings example, 2. how to connect database in visual studio data explorer



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

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
info :   OK 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).