Extensions.Configuration.EntityFrameworkCore/RAIC.Extensions.Configuration.EntityFrameworkCore/Extensions/ConfigurationBuilderExtensions.cs

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;

namespace RAIC.Extensions.Configuration.EntityFrameworkCore.Extensions;

public static class ConfigurationBuilderExtensions
{
    public delegate DbContextOptionsBuilder<T> DbContextOptionsTransformer<T>(DbContextOptionsBuilder<T> transform) where T : DbContext;

    /// <summary>
    /// Adds a <see cref="DbSet{}"/> off <typeparamref name="TDbContext"/> as a configuration provider to the <see cref="IConfigurationBuilder"/>.
    /// </summary>
    /// <typeparam name="TDbContext">Type of the <see cref="DbContext"/> which implements both <see cref="ISettingsDbContext{}"/> and <see cref="ISettingsDbContextFactory{}"/></typeparam>
    /// <param name="optionsTransformer">
    /// a <see cref="DbContextOptionsTransformer{}"/> which configures your <see cref="DbContextOptions{}"/>. eg.
    /// <code>
    ///   dbContextOptions => dbContextOptions.UseNpgsql(builder.Configuration.GetConnectionString("Default"))
    /// </code>
    /// </param>
    /// <returns>The <see cref="IConfigurationBuilder"/></returns>
    public static IConfigurationBuilder AddDbContext<TDbContext>(this IConfigurationBuilder builder, DbContextOptionsTransformer<TDbContext> optionsTransformer)
        where TDbContext : DbContext, ISettingsDbContext<System.Linq.IQueryable<ISetting>>, ISettingsDbContextFactory<TDbContext>
    {
        var options = optionsTransformer(new DbContextOptionsBuilder<TDbContext>()).Options;
        var configurationSource = new EntityFrameworkCoreDbSetConfigurationSource<TDbContext>()
        {
            DbContextFactory = () => TDbContext.Create(options)
        };

        return builder.Add(configurationSource);
    }
}