问题
I am trying to use ADO.Net Codefirst feature of latest Entity Framework 4.0. As part of that I have installed Entity Framework CTP 4 from Microsft and using Scott's tutorial to create the model first. Inside the tutorial DBContext and DBSet<> is specified. Could some tell what is the reference to be used in order to access this class.
I have used the following references however nothing happens for DBContext and DBSet<>
- System.Data.Entity
- System.Data.Entity.Design
回答1:
Use CTP5 instead it is newer version with some changes in API. You have to add reference to EntityFramework.dll which is installed in CTP directory - default is: c:\Program Files\Microsoft ADO.NET Entity Framework Feature CTP5\Binaries\EntityFramework.dll for 32bit system. On 64bit system it will be placed in Program Files (x86).
回答2:
You can use the Library Package Manager if you have it (it installs automatically with MVC 3.0).
From within your project in Visual Studio 2010, go to
Tools > Library Package Manager > Package Manager Console
From within your project in Visual Studio 2013, go to
Tools > NuGet Package Manager > Package Manager Console
In the console, after the PM> prompt, type
install-package entityframework
This will install the package and add the EntityFramework reference to your project.
回答3:
Use "DbContext" vs "DBContext", and "DbSet" vs "DBSet". The case sensitivity is the issue.
回答4:
To add EF to your project use the Package Manager Console and issue the command:
Install-Package EntityFramework
You shouldn't link directly to the DLLs' installed location as mentioned in another answer.
回答5:
The blogpost mentions the assembly:
The DbContext and DbSet classes used above are provided as part of the EF4 Code-First library. You’ll need to add a reference to the System.Data.Entity.CTP assembly that is installed into the \Program Files\Microsoft ADO.NET Entity Framework Feature CTP4\Binaries directory to reference these classes. You’ll also want to add a “using System.Data.Entity” namespace statement at the top of your “NerdDinners” class file.
However I do believe the new CTP5 includes some changes to codefirst, so I would suggest to take a look at that one instead.
回答6:
I was following the MvcMusicStore Tutorial (using Mvc 4 instead of Mvc 3).
I found in Part 4 I was having issues with this (http://www.asp.net/mvc/tutorials/mvc-music-store/mvc-music-store-part-4).
When I added the following reference using System.Data.Entity;, I got the following error:
the type or namespace name 'entity' does not exist in the namespace 'system.data'
@Fecklmore's solution worked for me.
Open the Package Manager Console by going to Tools > Library Package Manager > Package Manager Console.
Then type in the following: Install-Package EntityFramework
This will install EntityFramework (i.e. EF) into your project, and will eliminate the error above.
回答7:
if you are using .NET 3.5 then change your target framework to .NET 4.0
来源：https://stackoverflow.com/questions/4898742/references-for-dbcontext-dbset-in-entity-framework