EntityFramework.Triggers

Add triggers to your entities with insert, update, and delete events. There are three events for each: before, after, and upon failure.

This repo contains the code for both the EntityFramework and EntityFrameworkCore projects, as well as the ASP.NET Core support projects.

Nuget packages for triggers

EF version	.NET support	NuGet package
>= 6.1.3	>= Framework 4.6.1
>= Core 2.0	>= Framework 4.6.1 || >= Standard 2.0

Nuget packages for ASP.NET Core dependency injection methods

EF version	.NET support	NuGet package
>= 6.1.3	>= Framework 4.6.1
>= Core 2.0	>= Framework 4.6.1 || >= Standard 2.0

Basic usage with a global singleton

To use triggers on your entities, simply have your DbContext inherit from DbContextWithTriggers. If you can't change your DbContext inheritance chain, you simply need to override your SaveChanges... as demonstrated below

public abstract class Trackable {
	public DateTime Inserted { get; private set; }
	public DateTime Updated { get; private set; }

	static Trackable() {
		Triggers<Trackable>.Inserting += entry => entry.Entity.Inserted = entry.Entity.Updated = DateTime.UtcNow;
		Triggers<Trackable>.Updating += entry => entry.Entity.Updated = DateTime.UtcNow;
	}
}

public class Person : Trackable {
	public Int64 Id { get; private set; }
	public String Name { get; set; }
}

public class Context : DbContextWithTriggers {
	public DbSet<Person> People { get; set; }
}

As you may have guessed, what we're doing above is enabling automatic insert and update stamps for any entity that inherits Trackable. Events are raised from the base class/interfaces, up to the events specified on the entity class being used. It's just as easy to set up soft deletes (the Deleting, Updating, and Inserting events are cancellable from within a handler, logging, auditing, and more!).

Usage with dependency injection

This library fully supports dependency injection. The two features are:

1. Injecting the triggers and handler registrations to avoid the global singleton in previous versions

serviceCollection
	.AddSingleton(typeof(ITriggers<,>), typeof(Triggers<,>))
	.AddSingleton(typeof(ITriggers<>), typeof(Triggers<>))
	.AddSingleton(typeof(ITriggers), typeof(Triggers));

2. Using injected services right inside your global handlers

Triggers<Person, Context>().GlobalInserted.Add<IServiceBus>(
	entry => entry.Service.Broadcast("Inserted", entry.Entity)
);

Triggers<Person, Context>().GlobalInserted.Add<(IServiceBus Bus, IServiceX X)>(
	entry => {
		entry.Service.Bus.Broadcast("Inserted", entry.Entity);
		entry.Service.X.DoSomething();
	}
);

3. Using injected services right inside your injected handlers

public class Startup
{
	public void ConfigureServices(IServiceCollection services)
	{
		...
		services.AddDbContext<Context>();
		services.AddTriggers();
	}

	public void Configure(IApplicationBuilder app, IHostingEnvironment env)
	{
		...
		app.UseTriggers(builder =>
		{
			builder.Triggers().Inserted.Add(
				entry => Debug.WriteLine(entry.Entity.ToString())
			);
			builder.Triggers<Person, Context>().Inserted.Add(
				entry => Debug.WriteLine(entry.Entity.FirstName)
			);

			// receive injected services inside your handler, either with just a single service type or with a value tuple of services
			builder.Triggers<Person, Context>().GlobalInserted.Add<IServiceBus>(
				entry => entry.Service.Broadcast("Inserted", entry.Entity)
			);
			builder.Triggers<Person, Context>().GlobalInserted.Add<(IServiceBus Bus, IServiceX X)>(
				entry => {
					entry.Service.Bus.Broadcast("Inserted", entry.Entity);
					entry.Service.X.DoSomething();
				}
			);
		});
	}
}

How to enable triggers if you can't derive from DbContextWithTriggers

If you can't easily change what your DbContext class inherits from (ASP.NET Identity users, for example), you can override your SaveChanges... methods to call the SaveChangesWithTriggers... extension methods. Alternatively, you can call SaveChangesWithTriggers... directly instead of SaveChanges... if, for example, you want to control which changes cause triggers to be fired.

class YourContext : DbContext {
	// Your usual DbSet<> properties

	#region If you're targeting EF 6
	public override Int32 SaveChanges() {
		return this.SaveChangesWithTriggers(base.SaveChanges);
	}
	public override Task<Int32> SaveChangesAsync(CancellationToken cancellationToken) {
		return this.SaveChangesWithTriggersAsync(base.SaveChangesAsync, cancellationToken);
	}
	#endregion

	#region If you're targeting EF Core
	public override Int32 SaveChanges() {
		return this.SaveChangesWithTriggers(base.SaveChanges, acceptAllChangesOnSuccess: true);
	}
	public override Int32 SaveChanges(Boolean acceptAllChangesOnSuccess) {
		return this.SaveChangesWithTriggers(base.SaveChanges, acceptAllChangesOnSuccess);
	}
	public override Task<Int32> SaveChangesAsync(CancellationToken cancellationToken = default(CancellationToken)) {
		return this.SaveChangesWithTriggersAsync(base.SaveChangesAsync, acceptAllChangesOnSuccess: true, cancellationToken: cancellationToken);
	}
	public override Task<Int32> SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken = default(CancellationToken)) {
		return this.SaveChangesWithTriggersAsync(base.SaveChangesAsync, acceptAllChangesOnSuccess, cancellationToken);
	}
	#endregion
}

#region If you didn't/can't override `SaveChanges...`, you can (not recommended) call 
dbContext.SaveChangesWithTriggers(dbContext.SaveChanges);
dbContext.SaveChangesWithTriggersAsync(dbContext.SaveChangesAsync);
#endregion

Longer example (targeting EF6 for now)

using System;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Data.Entity.Migrations;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using EntityFramework.Triggers;

namespace Example {
	public class Program {
		public abstract class Trackable {
			public virtual DateTime Inserted { get; private set; }
			public virtual DateTime Updated { get; private set; }

			static Trackable() {
				Triggers<Trackable>.Inserting += entry => entry.Entity.Inserted = entry.Entity.Updated = DateTime.UtcNow;
				Triggers<Trackable>.Updating += entry => entry.Entity.Updated = DateTime.UtcNow;
			}
		}

		public abstract class SoftDeletable : Trackable {
			public virtual DateTime? Deleted { get; private set; }

			public Boolean IsSoftDeleted => Deleted != null;
			public void SoftDelete() => Deleted = DateTime.UtcNow;
			public void SoftRestore() => Deleted = null;

			static SoftDeletable() {
				Triggers<SoftDeletable>.Deleting += entry => {
					entry.Entity.SoftDelete();
					entry.Cancel = true; // Cancels the deletion, but will persist changes with the same effects as EntityState.Modified
				};
			}
		}

		public class Person : SoftDeletable {
			public virtual Int64 Id { get; private set; }
			public virtual String FirstName { get; set; }
			public virtual String LastName { get; set; }
		}

		public class LogEntry {
			public virtual Int64 Id { get; private set; }
			public virtual String Message { get; set; }
		}

		public class Context : DbContextWithTriggers {
			public virtual DbSet<Person> People { get; set; }
			public virtual DbSet<LogEntry> Log { get; set; }
		}
		internal sealed class Configuration : DbMigrationsConfiguration<Context> {
			public Configuration() {
				AutomaticMigrationsEnabled = true;
			}
		}

		static Program() {
			Triggers<Person, Context>.Inserting += e => {
				e.Context.Log.Add(new LogEntry { Message = "Insert trigger fired for " + e.Entity.FirstName });
				Console.WriteLine("Inserting " + e.Entity.FirstName);
			};
			Triggers<Person>.Updating += e => Console.WriteLine($"Updating {e.Original.FirstName} to {e.Entity.FirstName}");
			Triggers<Person>.Deleting += e => Console.WriteLine("Deleting " + e.Entity.FirstName);
			Triggers<Person>.Inserted += e => Console.WriteLine("Inserted " + e.Entity.FirstName);
			Triggers<Person>.Updated += e => Console.WriteLine("Updated " + e.Entity.FirstName);
			Triggers<Person>.Deleted += e => Console.WriteLine("Deleted " + e.Entity.FirstName);
		}
		
		private static void Main(String[] args) => Task.WaitAll(MainAsync(args));

		private static async Task MainAsync(String[] args) {
			using (var context = new Context()) {
				context.Database.Delete();
				context.Database.Create();

				var log = context.Log.ToList();
				var nickStrupat = new Person {
					FirstName = "Nick",
					LastName = "Strupat"
				};

				context.People.Add(nickStrupat);
				await context.SaveChangesAsync();

				nickStrupat.FirstName = "Nicholas";
				context.SaveChanges();
				context.People.Remove(nickStrupat);
				await context.SaveChangesAsync();
			}
		}
	}
}

See also

• https://github.com/NickStrupat/EntityFramework.Rx for hot observables of your EF operations
• https://github.com/NickStrupat/EntityFramework.PrimaryKey to easily get the primary key of any entity (including composite keys)
• https://github.com/NickStrupat/EntityFramework.TypedOriginalValues to get a proxy object of the orginal values of your entity (typed access to Property("...").OriginalValue)
• https://github.com/NickStrupat/EntityFramework.SoftDeletable for base classes which encapsulate the soft-delete pattern (including keeping a history with user id, etc.)
• https://github.com/NickStrupat/EntityFramework.VersionedProperties for a library of classes which auto-magically keep an audit history of the changes to the specified property

Contributing

1. Create an issue
2. Let's find some point of agreement on your suggestion.
3. Fork it!
4. Create your feature branch: git checkout -b my-new-feature
5. Commit your changes: git commit -am 'Add some feature'
6. Push to the branch: git push origin my-new-feature
7. Submit a pull request :D

History

Commit history

License

MIT License