Entity Framework Core

https://learn.microsoft.com/ef/core

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### Define a BloggingContext and Entity Classes

Source: https://learn.microsoft.com/ef/core

This example demonstrates defining a DbContext class for database sessions and entity classes for Blogs and Posts.

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

namespace Intro;

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

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer(
            @"Server=(localdb)\mssqllocaldb;Database=Blogging;Trusted_Connection=True;ConnectRetryCount=0");
    }
}

public class Blog
{
    public int BlogId { get; set; }
    public string Url { get; set; }
    public int Rating { get; set; }
    public List<Post> Posts { get; set; }
}

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; }
}
```

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### Retrieve data with LINQ

Source: https://learn.microsoft.com/ef/core

Uses LINQ to filter and order entity instances from the database asynchronously.

```csharp
using (var db = new BloggingContext())
{
    var blogs = await db.Blogs
        .Where(b => b.Rating > 3)
        .OrderBy(b => b.Url)
        .ToListAsync();
}
```

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### Save data to the database

Source: https://learn.microsoft.com/ef/core

Adds a new entity instance to the context and persists the changes to the database.

```csharp
using (var db = new BloggingContext())
{
    var blog = new Blog { Url = "http://sample.com" };
    db.Blogs.Add(blog);
    await db.SaveChangesAsync();
}
```

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