N-Tier Support for Entity Framework with WCF or ASP.NET Web API
Trackable Entities supports tracking changes to entities in an object graph, so that they can be sent to a web service and persisted in a single round trip and within a single transaction. This functionality is provided as a set of NuGet packages.
The server-side NuGet packages provide an
ApplyChangesextension method to Entity Framework's
DbContextclass, which traverses one or more object graphs, informing Entity Framework of each entity's change state. After calling
SaveChanges, you can then call
AcceptChangesto set the state of all entities to
Unchangedbefore returning them to the client. There is also a
LoadRelatedEntitiesmethod which you can call to populate reference properties on added entities.
The client-side packages provide a change-tracker for marking entities as
Deletedwhenever they are inserted, modified or removed at any level in an object graph. To start tracking changes, simply add one or more entities to a
ChangeTrackingCollectionand set the
true. When you want to persist changes, you can call
GetChangeson the change tracker to get only changed items, so that unchanged entities need not be sent to the server, saving bandwidth and increasing performance. Trackable Entities will correlate entities so that you can merge updated entities back into the original object graph by calling
MergeChanges. While you can certainly set
TrackingStateon entities manually, the change tracker is deployed as a portable class library, so you can use it from any .NET client, including desktop or mobile applications.
While you can use the NuGet packages by themselves, Trackable Entities provides a powerful Visual Studio extension, which you can install from within Visual Studio 2012, 2013 or 2015, by selecting Extensions and Updates from the Tools menu and searching for "Trackable Entities" in the Visual Studio online extensions gallery.
After installing the VS extension, you will be able to add a Trackable Entities Class Library to an existing solution, selecting the kind of entities you wish to create: Service, Client or Shared (.NET 4.5 or Portable). The resulting project will include customizable T4 templates for generating entity classes from an Entity Framework data model (EDMX or Code First).
Trackable Entities also provides several Visual Studio multi-project templates which include all the projects needed to build a complete n-tier solution with end-to-end change tracking. All the NuGet packages are present and inter-project references are correctly set. This allows you to see how all the pieces fit together and can be a huge time-saver when you want to get up and running quickly. To build an n-tier solution with Trackable Entities and Entity Framework, you can choose from the following Visual Studio project templates, which you will see under the Trackable category in the New Project dialog:
You will then find a number of Visual Studio item templates to add WCF services, Web API controllers, and repository or unit of work classes. The template for repository and unit of work patterns will install NuGet packages which include generic base classes for these patterns as well as bootstrap code for wiring up a dependency injection framework.
If you have questions, comments or bugs to report, please open an issue on the Trackable Entities GitHub repository. You may also contact me directly. Enjoy!
Tony Sneed - Twitter: @tonysneed - Email: [email protected]eed.com