How to get a .NET core 3.1 Project work with .NET 5.0 project - asp.net-core-3.1

When .NET 5.0 was released, one of the features mentioned was the ability to create a .NET 5.0 component, that it would work with .NET 3.1, so you wouldn't have to use .net standard between different versions.
Well, I tried to use .net 3.1 with .net 5.0 and I keep getting errors. Is there something special we have to do to make these work? We have multiple applications at my company that use various versions of .NET core. from 2.2, 3.0, 3.1 to .net 5.0. We would like to create some NuGet packages for some of the reusable components, but trying to figure out how to use .net core through out these applications, I don't want to create them with .net standard.
Has anyone run into this or not?

You did not provide the errors, but despite that, it can already be said that .NET 5 does not ensure backwards compatibility. Microsoft provides information on compatibility and breaking changes here.
.NET 5 merges together .NET Framework and .NET Core, ending the burden of keeping both; the aim is to also include Mono and Xamarin (MAUI). However, it does not ensure compatibility with previous versions. This is a good article on the subject - some features were delayed to .NET 6 though.
Hence, the best ways for you to have the compatibility you want would be to use .NET Standard or, even better, migrate the applications to .NET 5, since previous versions' support will end soon. In the team I work, we made some migrations from .NET Core 3.x to .NET 5 and it was pretty straightforward.
It is worth noticing that .NET 5 is not LTS. .NET 6, on the other hand, is. More details on .NET releases and support policies here.

A .net 5.0 library/dll cannot be referenced from a .net version less than .net 5.0. .net standard 2.1 should be used for compatibility between the different versions of .net core and .net 5.0.
On another note - its probably best to update all .net core projects to 5.0 assuming this is possible. The End of Life has been reached on .net core versions <= 3.0 (not .net standard).
see here.

Related

How to use EF Core 6.0 with an application that uses .Net Framework?

I have a situation where an application uses various component libraries. The libraries were based on .NetStandard2.0/2.1 and internally used EF Core 3.1. For various deployment and development reasons, we now want to target EF Core 6.0, which raises the following issues.
Net Core 3.1 support runs out in December 2022 so we need to move away from it.
The application uses Net Framework functionality and cannot move to Net Core.
EF Core 6.0 does not support NetStandard, only Net 6.
Changing the library that uses EF Core to target NET 6 means that components referencing it also need to reference Net 6.
Dependencies trickle down to the application that targets Net Framework and, as a result, the application no longer builds because Net Framework is not compatible Net 6.
How can the Net Framework application use the Net 6 assembly? Or, more specifically, how can a Net Framework application use libraries that internally use EF Core 6.0?
The interface between the application (Net Framework) and the one single touch point library component (Netstandard) is very well defined. Maybe Pinvoke could solve the problem? Or something simpler that I have overlooked?
Somewhat related question: NU1202 Package Microsoft.EntityFrameworkCore 6.0.3 is not compatible with netstandard2.1
Other than process to process communication between .NET Framework and .NET 6, this is not supported (for example via a Web API or similar)
As a short term solution, you can change your .Net Standard 2.0 EF Core libraries to be multi targeted to both .Net Standard 2.0 (which will reference EF Core 3.1) and .Net 6 (which will reference EF Core 6). This will let your .Net Core apps use EF Core 6, while allowing your .Net Framework apps to use the same dlls, but to be using EF Core 3.1. I realize that EF Core 3.1 support ends December 2022, but it will keep things moving.
https://learn.microsoft.com/en-us/nuget/create-packages/multiple-target-frameworks-project-file
Btw, has Microsoft even attempted to address the fact that a .Net Framework application cannot reference .Net 6, therefore it cannot use EF Core 6? This is a major issue for us, as we were sold the idea that .Net Standard could be shared between .Net Framework and .Net Core, but this has ceased to be the case since .Net Standard 2.1 was introduced, and now MS has pushed all new features, like EF Core, to .Net 6.

Should I upgrade to EntityFrameWorkCore 5.x when using .Net Core 3.x?

I have a multi-project solution that contains a data layer on .Net Standard 2.1 and a WebAPI on .Net Core 3.1. Currently, I have no plans to upgrade to .Net 5.x (Note: Core is removed in 5.x naming convention) because it is not LTS - that will be .Net 6.x. So, I will upgrade to 6.x when it comes out.
In one of my data layer solutions, the NuGet Package Manager is recommending that I upgrade Microsoft.AspNetCore.Identity.EntityFrameWorkCore from v3.1.8 to v5.0.2. It seems like the major version is moving in lockstep with the .Net major version (Note: 4.x is skipped in order to avoid confusion with the venerable .Net Framework 4.x). Should I follow the advice and upgrade?
Specifically, will this cause any problems with the .Net Core 3.1 WebAPI project? Generally, can I do this for other Microsoft.* packages that recommend upgrading to a 5.x version?
I bit the bullet and upgraded all of them. Everything works flawlessly and I am glad that I did it. There were a few breaking changes that needed to be dealt with. I recommend checking Microsoft's breaking change log here:
https://learn.microsoft.com/en-us/aspnet/core/migration/31-to-50?view=aspnetcore-5.0&tabs=visual-studio

Can Entity Framework 6 be used in a .NET Standard project?

And if not, will it be? If so, when?
I haven't been able to find any clear official information on this, and the limited information I was able to find on Stack Overflow is a year or two old.
I was able to find official information saying EF 6.3 will be able to be used in a .NET Core project, but I couldn't find a release date for it, nor am I sure what the implications for use in a .NET Standard project are.
EF 6 supports .NET Standard 2.1, which is currently supported by .NET Core 3.0 or later - no .NET Framework version. EF 6 also supports .NET 4.0 and 4.5 or later.
https://github.com/aspnet/EntityFramework6/blob/release/6.4/src/EntityFramework/EntityFramework.csproj#L6
Some clarification, since EntityFramework 6.3.0 .NET Standard 2.1 has been supported. However there is no .NET Framework version that supports .NET Standard 2.1. Comment from Microsoft:
NET Framework won't support .NET Standard 2.1 or later versions. For
more details, see the announcement of .NET Standard 2.1.
This means that a majority of all applications using EntityFramework 6.X won't be able to use the .NET Standard 2.1 project anyway.
https://learn.microsoft.com/en-us/dotnet/standard/net-standard
https://www.nuget.org/packages/EntityFramework/#

Upgrading from the June CTP EF 4.2

We're currently developing an application that is using EF Code first (EF June 2011 CTP).
My first question is: Is it worth trying to upgrade to use a later version of EF?
Secondly, if so, does anyone know the steps involved to upgrade - when I try to install the NuGet package for EF 5.0 - beta 2, I end up with issues as the target framework is still 4.2.
Many thanks,
James.
The CTP is long time dead with no other version coming because all that stuff is currently part of .NET 4.5 beta and EF 5.0 beta. You must upgrade to those two and the upgrade will consist of re-targeting application back to .NET 4.0 / .NET 4.5, removing all dependencies to your current EF version and re-adding those dependencies for .NET 4.5 / EF 5.0.
Some time ago I wrote a blog post on this: http://blog.3d-logic.com/2012/04/11/entity-framework-zombie-a-k-a-microsoft-entity-framework-june-2011-ctp/. There is a number of issues with CTP 4.2 because of technical challenges related to shipping a .NET Framework library out of the .NET Framework (like 4.2 target). Move to .NET Framework 4.5 that contains the same feature set as EF 4.2 + bug fixes and has a go-live license. Use EF 5.0 on top of it and you will be in a better world.
Thanks for all the responses.
My main issue is that we rely heavily on ENUMs in our implementation of 4.2 code first. I attempted to migrate the project to 4.5 but ENUMs are not supported, and there is also an issue with table per hierarchy (which is easy to fix). The next move will be to upgrade to VS11 and use 5.0 - but this is a big undertaking.
#jwsadler:
Enums are supported by core EF libraries released as part of .net Framework 4.5 (e.g. System.Data.Entity.dll). To make enums work with CodeFirst/DbContext you do need EF 5.0.0 package from NuGet (use Install-Package EntityFramework -pre (-pre is important)). You need VS 11 for this since Visual Studio 2010 cannot be used to create applications that target .NET Framework 4.5. Note that when installing the nuget package on Visual Studio 11 the target version of the .NET Framework set for the project is taken into account. If you target .NET Framework 4 you will not be able to use EF5 features like enums or spatial.

Sharepoint 2010 Foundation with .Net Framework 4.0

I am having a Web Application with build target as .Net Framework 4.0.
I want to interact with the Sharepoint Object Model API's but it gives a framework 4.0 runtime does not supports Sharepoint.dll error.
Is their any tweak such that I can use Sharepoint 2010 with .Net Framework4.0.
Note: I cannnot change the build target of the web app to any other framework as I am using some exclusive features of .net 4.0 in my application.
Sorry you probably will have no luck:
There appears to be some confusion
around whether or not ASP.NET 4 is
supported for both MOSS and SharePoint
2010 - in short, the answer is that it
is not currently supported in either
product.
Whilst it is possible to use ASP.NET
3.5 in MOSS by making some modifications to the SharePoint site
web.config (instructions for doing
that in MOSS here; SP2010 uses 3.5 by
default), this is unfortunately not
the case with version 4.
The reason? ASP.NET 4 uses a new
version of the Common Language Runtime
(CLR). Whilst .NET 2.0, 3.0 and 3.5
all used version 2.0 of the CLR, .NET
4 uses version 4. I'm not entirely
sure what happened to version 3. There
is a decent post on stack overflow
with further details.
from SharePoint 2010 and .NET 4: confused?
Maybe .NET 4.0 Support will be added in a future update (SP1?) who knows...
Unfortunately, .Net 2.0 to 3.5 use a different application pool type from .Net 4.0; Mixing in the same app pool is not going to work.
What features of .Net 4.0 are you using, and perhaps the community can help you with a 3.5 solution?