A trial .NET Core console app that performs data access against a SQLite database using Entity Framework Core.

README.md

Steps

• Prerequisites: Visual Studio 2019 version 16.3+ with .NET Core cross-platform development.
• Install Entity Framework Core.

  Install-Package Microsoft.EntityFrameworkCore.Sqlite

• Create the database after having Model.cs.

  Install-Package Microsoft.EntityFrameworkCore.Tools
  Add-Migration InitialCreate
  Update-Database

• Debugging as a console app.

Insights

• Software design: Context.
• In EF Core, the DB context is constructed in a way of
  • Encapsulate data models as DbSet, to query and save instances of data entities.
  • Config DB (Path, Database, Strategy etc.), for example SQLite, in the constructor for each of the contexts created.
  • and then expose CRUD interfaces in DB context to developers of LINQ queires.

EFCoreApp.cs

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;

public class BloggingContext : DbContext
{
    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }

    public string DbPath { get; }

    public BloggingContext()
    {
        var folder = Environment.SpecialFolder.LocalApplicationData;
        var path = Environment.GetFolderPath(folder);
        DbPath = System.IO.Path.Join(path, "blogging.db");
    }

    // Config the DB used for the context.
    // The method is called for each instance of the context created.
    protected override void OnConfiguring(DbContextOptionsBuilder options)
        => options.UseSqlite($"Data Source={DbPath}");
}

public class Blog
{
    public int BlogId { get; set; }
    public string Url { get; set; }
    public List<Post> Posts { get; } = new();
}

public class Post
{
    public int PostId { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }

    public int BlogId { get; set; }
    public Blog Blog { get; set; }
}

Program.cs

using System;
using System.Linq;

using var db = new BloggingContext();

Console.WriteLine($"Database path: {db.DbPath}.");

// Create
Console.WriteLine("Inserting a new blog");
db.Add(new Blog { Url = "http://blogs.msdn.com/adonet" });
db.SaveChanges();

// Read
Console.WriteLine("Querying for a blog");
var blog = db.Blogs
    .OrderBy(b => b.BlogId)
    .First();

// Update
Console.WriteLine("Updating the blog and adding a post");
blog.Url = "http://devblogs.microsoft.com/dotnet";
blog.Posts.Add( new Post { Title = "Hello World", Content = "Trails on EF Core"});
db.SaveChanges();

// Delete
Console.WriteLine("Delete the blog");
db.Remove(blog);
db.SaveChanges();