Entity Framework Query Batching

I’ve been an NHibernate fan for a long time, but on my recent projects I’m making the switch to Entity Framework.

Although I like the overall experience, there are still lot of features missing.

One of the things I liked about NHibernate was the support for query batching using the NHibernate Future<> syntax.

This allowed you to write multiple simpler queries instead of writing one complex one. The moment you try to read one query result, all batched queries are sent in 1 command(!) to the database and the results are returned.

	// prepare the query
	var query = session.CreateQuery("from Person p where p.Id = :id")
	.SetParameter("id", person.Id)
	.Future<Person>();
	// eager load first collection
	session.CreateQuery("from Person p
	left join fetch p.Addresses a where p.Id = :id")
	.SetParameter("id", person.Id)
	.Future<Person>();
	// eager load second collection
	session.CreateQuery("from Person p
	left join fetch p.Phones ph
	left join fetch ph.PhoneType pt where p.Id = :id")
	.SetParameter("id", person.Id)
	.Future<Person>();

view raw NHibernateFuture.cs hosted with ❤ by GitHub

Although a similar feature does not exist in Entity Framework out-of-the-box, you can use the EntityFramework.Extended library to get this functionality. This library extends the functionality of Entity Framework with the following features:

• Batch Update and Delete
• Future Queries
• Query Result Cache
• Audit Log

In this case I’m looking at the Future Queries feature:

	// build up queries
	var q1 = db.Users
	.Where(t => t.EmailAddress == "one@test.com")
	.Future();
	var q2 = db.Tasks
	.Where(t => t.Summary == "Test")
	.Future();
	// this triggers the loading of all the future queries
	var users = q1.ToList();

view raw EntityFrameworkFuture.cs hosted with ❤ by GitHub