Table of Contents

Entity Framework Core

In this guide we will set up EFCore with a PostgreSQL database. Information on other databases will be at the bottom of this page.

Prerequisites

  • A simple bot with dependency injection configured
  • A running PostgreSQL instance
  • EFCore CLI tools

Downloading the required packages

You can install the following packages through your IDE or go to the nuget link to grab the dotnet cli command.

Name Link
Microsoft.EntityFrameworkCore link
Npgsql.EntityFrameworkCore.PostgreSQL link

Configuring the DbContext

To use EFCore, you need a DbContext to access everything in your database. The DbContext will look like this. Here is an example entity to show you how you can add more entities yourself later on.

// ApplicationDbContext.cs
using Microsoft.EntityFrameworkCore;

public class ApplicationDbContext : DbContext
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options)
    {

    }

    public DbSet<UserEntity> Users { get; set; } = null!;
}

// UserEntity.cs
public class UserEntity
{
    public ulong Id { get; set; }
    public string Name { get; set; }
}
Note

To learn more about creating the EFCore model, visit the following link

Adding the DbContext to your Dependency Injection container

To add your newly created DbContext to your Dependency Injection container, simply use the extension method provided by EFCore to add the context to your container. It should look something like this

private static ServiceProvider ConfigureServices()
{
    return new ServiceCollection()
        .AddDbContext<ApplicationDbContext>(
          options => options.UseNpgsql("Your connection string")
        )
        [...]
        .BuildServiceProvider();
}
Note

You can find out how to get your connection string here

Migrations

Before you can start using your DbContext, you have to migrate the changes you've made in your code to your actual database. To learn more about migrations, visit the official Microsoft documentation here

Using the DbContext

You can now use the DbContext wherever you can inject it. Here's an example on injecting it into an interaction command module.

using Discord;

public class SampleModule : InteractionModuleBase<SocketInteractionContext>
{
    private readonly ApplicationDbContext _db;

    public SampleModule(ApplicationDbContext db)
    {
        _db = db;
    }

    [SlashCommand("sample", "sample")]
    public async Task Sample()
    {
        // Do stuff with your injected DbContext
        var user = _db.Users.FirstOrDefault(x => x.Id == Context.User.Id);

        ...
  }
}

Using a different database provider

Here's a couple of popular database providers for EFCore and links to tutorials on how to set them up. The only thing that usually changes is the provider inside of your DbContextOptions

Provider Link
MySQL link
SQLite link
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