The Entity Framework team recently announced
the 2nd alpha release of EF6.
The alpha 2 package is available for download from NuGet. Since this is a pre-release package make sure to select “Include Prereleases” in
the NuGet package manager, or execute
the following from
the package manager console to install it: PM> Install-Package EntityFramework -Pre This week’s alpha release includes a bunch of
great improvements in
the following areas: Async language support is now available for queries and updates when running on .NET 4.5. Custom conventions now provide
the ability to override
the default conventions that Code First uses for mapping types, properties, etc. to your database. Multi-tenant migrations allow
the same database to be used by multiple contexts with full Code First Migrations support for independently evolving
the model backing each context. Using Enumerable.Contains in a LINQ query is now handled much more efficiently by EF and
the SQL Server provider resulting greatly improved performance. All features of EF6 (except async) are available on both .NET 4 and .NET 4.5. This includes support for enums and spatial types and
the performance improvements that were previously only available when using .NET 4.5. Start-up time for many large models has been dramatically improved thanks to improved view generation performance. Below are some additional details about a few of
the improvements above: Async Support .NET 4.5 introduced
the Task-Based Asynchronous Pattern that uses
the async and await keywords to help make writing asynchronous code easier. EF 6 now supports this pattern. This is
great for ASP.NET applications as database calls made through EF can now be processed asynchronously – avoiding any blocking of worker threads. This can increase scalability on
the server by allowing more requests to be processed while waiting for
the database to respond.
The following code shows an MVC controller that is querying a database for a list of location entities: public class HomeController : Controller { LocationContext db = new LocationContext(); public async Task<ActionResult> Index() { var locations = await db.Locations.ToListAsync(); return View(locations); } } Notice above
the call to
the new ToListAsync method with
the await keyword. When
the web server reaches this code it initiates
the database request, but rather than blocking while waiting for
the results to come back,
the thread that is processing
the request returns to
the thread pool, allowing ASP.NET to process another incoming request with
the same thread. In other words, a thread is only consumed when there is actual processing work to do, allowing
the web server to handle more concurrent requests with
the same resources. A more detailed walkthrough covering async in EF is available with additional information and examples. Also a walkthrough is available showing how to use async in an ASP.NET MVC application. Custom Conventions When working with EF Code First,
the default behavior is to map .NET classes to tables using a set of conventions baked into EF. For example, Code First will detect properties that end with “ID” and configure them automatically as primary keys. However, sometimes you cannot or do not want to follow those conventions and would rather provide your own. For example, maybe your primary key properties all end in “Key” instead of “Id”. Custom conventions allow
the default conventions to be overridden or new conventions to be added so that Code First can map by convention using whatever rules make sense for your project.
The following code demonstrates using custom conventions to set
the precision of all decimals to 5. As with other Code First configuration, this code is placed in
the OnModelCreating method which is overridden on your derived DbContext class: protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Properties<decimal>() .Configure(x => x.HasPrecision(5)); } But what if there are a couple of places where a decimal property should have a different precision? Just as with all
the existing Code First conventions, this new convention can be overridden for a particular property simply by explicitly configuring that property using either
the fluent API or a data annotation. A more detailed description of custom code first conventions is available here. Community Involvement I blogged a while ago about EF being released under an open source license. Since then a number of community members have made contributions and these are included in EF6 alpha 2. Two examples of community contributions are: AlirezaHaghshenas contributed a change that increases
the startup performance of EF for larger models by improving
the performance of view generation.
The change means that it is less often necessary to use of pre-generated views. UnaiZorrilla contributed
the first community feature to EF:
the ability to load all Code First configuration classes in an assembly with a single method call like
the following: protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Configurations .AddFromAssembly(typeof(LocationContext).Assembly); } This code will find and load all
the classes that inherit from EntityTypeConfiguration<T> or ComplexTypeConfiguration<T> in
the assembly where LocationContext is defined. This reduces
the amount of coupling between
the context and Code First configuration classes, and is also a very convenient shortcut for large models. Other upcoming features coming in EF 6 Lots of information about
the development of EF6 can be found on
the EF CodePlex site, including a roadmap showing
the other features that are planned for EF6. One of of
the nice upcoming features is connection resiliency, which will automate
the process of retying database operations on transient failures common in cloud environments and with databases such as
the Windows Azure SQL Database. Another often requested feature that will be included in EF6 is
the ability to map stored procedures to query and update operations on entities when using Code First. Summary EF6 is
the first open source release of Entity Framework being developed in CodePlex.
The alpha 2 preview release of EF6 is now available on NuGet, and contains some really
great features for you to try.
The EF team are always looking for feedback from developers - especially on
the new features such as custom Code First conventions and async support. To provide feedback you can post a comment on
the EF6 alpha 2 announcement post, start a discussion or file a bug on
the CodePlex site. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu
