.NET 4.0替代.NET 4.5命名空间

Question

There is some code for an MVC application which was built using .NET 4.5 as a framework in VS 2012. My current system forces me to work on VS 2010. I managed to open the VS2012 solution in my VS2010, but the thing is that VS2010 supports only up to .NET 4.

There are a few functions in the code which use dll files which are available only for .NET 4.5, for example System.ComponentModel.DataAnnotations.Schema .

So, are there any substitute functions/attributes which are available in .NET 4, which I could use to do the same that is being done on .NET 4.5 right now?

This is my current code using .NET 4.5:

 [Table("UserProfile")]
    public class UserProfile
    {
        [Key]
        [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
        public int UserId { get; set; }
        public string UserName { get; set; }
    }

As you can see DatabaseGeneratedAttribute is available under the System.ComponentModel.DataAnnotations.Schema namespace, which is a part of .NET 4.5.

Any suggestions on what the corresponding functions/attributes that could be used in .NET 4 to represent the same logic?

Note: In the code snippet given above, I get errors on Table and DatabaseGeneratedAttribute as

The type or namespace name 'Table' could not be found (are you missing a using directive or an assembly reference?)

and

The type or namespace name 'DatabaseGeneratedAttributeAttribute' could not be found (are you missing a using directive or an assembly reference?)

respectively. So, I am guessing that I just need to find the corresponding classes in NET 4.0 and things would fall into place. Your help is deeply appreciated.

Answer 1

I saw the same issue after changing from .NET 4.5 to 4.0. According to this article "there is a special version of the Entity Framework assembly" for .NET 4.0 containing DataAnnotations , which have otherwise been incorporated into .NET 4.5.

Reinstalling Entity Framework made System.ComponentModel.DataAnnotations.Schema work again. Reinstall by typing the following in Package Manager Console:

Uninstall-Package EntityFramework
Install-Package EntityFramework

Answer 2

In this article , Author claims to be able to use System.ComponentModel.DataAnnotations.Schema in an MVC4 app using VS2010 SP1.

Let us know if this works out for you.

Answer 3

Henrik's solution also works for the opposite situation. I had an issue with going from .net 4.0 to .net 4.5.1 to support MVC 5.2.3. I got the same errors. Uninstalling and Re-Installing Entity Framework solved the problem in this situation as well:

Uninstall-Package EntityFramework
Install-Package EntityFramework

Answer 4

The Package Manager Console didnt work for me. I had to go Manage Nuget packages to get this issue resolved for me. I am using VS.net 2013