elliebot/src/EllieBot/Db/Models/GCChannelId.cs

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using System.ComponentModel.DataAnnotations;

namespace EllieBot.Db.Models;

public class GCChannelId : DbEntity
{
    public ulong GuildId { get; set; }
    public ulong ChannelId { get; set; }
}

public class GCChannelIdEntityConfiguration : IEntityTypeConfiguration<GCChannelId>
{
    public void Configure(EntityTypeBuilder<GCChannelId> builder)
    {
        builder.HasIndex(x => new
               {
                   x.GuildId,
                   x.ChannelId
               })
               .IsUnique();
    }
}