IWebHostEnvironment not working in one of the class library projects

vkagarwal 1

Hi,

I am working on a project which is based on .Net Core 3.1. I have couple of class library projects.

Both of the class library projects reference IWebHostEnvironment in the class constructor but one project builds successfully while another fails.

I have Microsoft.AspNetCore.Hosting nuget package referenced in both projects but still one works while other fails. I had to add Microsoft.AspNetCore.App nuget package to make other project build and work.

Why this is happening while both projects are in same solution and both projects are based on .Net Core 3.1

Thanks

Abdallah Ziada 1 Reputation point

2021-10-09T20:20:45.817+00:00

same problem here with dotnet 5

and found that IHostingEnvironment is replaced with IWebHostEnvironment in the versions above .Net core 3
and then in .Net Core 5 they replaced IWebHostEnvironment with IHostEnvironment

notice the confusing difference between older version IHostingEnvironment and the new version IHostEnvironment

also check this link

1 answer

Jerry Cai-MSFT 986 Reputation points

2021-06-29T08:17:00.493+00:00
Hi, vkagarwal

You can add

<ItemGroup> <FrameworkReference Include="Microsoft.AspNetCore.App" /> </ItemGroup>

to your project then solve the problem.

About the reason, you can check this :

Framework reference

Best Regards,
Jerry Cai

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vkagarwal 1 Reputation point

2021-06-29T16:25:07.843+00:00

Hi @Jerry Cai-MSFT I already mentioned that my both projects are in .net core 3.1 and Microsoft.AspNetCore.Hosting is referenced in both projects but it works in one project without Microsoft.AspNetCore.App while in another it does not work.

And I have not migrated project from .net core 2.2 to 3.1, both are already in .net core 3.1

Jerry Cai-MSFT 986 Reputation points

2021-07-02T09:36:32.443+00:00

Hi,@vkagarwal Could you please show the error code?

vkagarwal 1 Reputation point

2021-07-03T16:46:25.897+00:00

Solution simply does not compile. It shows Red squiggly lines under IWebHostEnvironment in project if I don't add reference of Microsoft.AspNetCore.App in csproj file but it works fine for another project in same solution without this reference.

Jerry Cai-MSFT 986 Reputation points

2021-07-05T06:48:36.553+00:00

How did you use IWebHostEnvironment, do you have some customize in it? I can use it in two projects under the same solution.

vkagarwal 1 Reputation point

2021-07-05T16:57:46.61+00:00

There is no customization. I just injected it as it should be in constructor IWebHostEnvironment environment

Williams Botchway 1 Reputation point

2021-07-10T19:16:36.073+00:00

I am using dotnet 5 and i am currently facing the same problem. the package Microsoft.AspNetCore.App is too huge only to obtain IWebHostEnvironment

AgaveJoe 26,201 Reputation points

2021-07-12T11:07:33.563+00:00

Keep in mind, a library that accesses IWebHostEnvironment depends on a hosted environment. Rather than injecting IWebHostEnvironment, pass values to the library using a constructor or method.

vkagarwal 1 Reputation point

2021-07-15T18:25:54.847+00:00

In both projects I have same code, both have same .Net Core 3.1
Below is code

public class ImageService : IImageService
{
private readonly IWebHostEnvironment _environment;

public ImageService(IWebHostEnvironment environment) { _environment = environment; } }

But this works in project 1 without Microsoft.AspNetCore.App package while project 2 gives build error without this package reference that you are missing library reference.

AgaveJoe 26,201 Reputation points

2021-07-15T18:54:27.71+00:00

Clearly, there are difference between the two projects. You are the only one that can compare these projects.

IMHO, the library design is questionable unless the library is only used in a hosted application. In this case, it does not matter if Microsoft.AspNetCore.App reference is added to the to the library because you'll only deploy the DLL anyway. The hosted project should have all the necessary binaries like the Microsoft.AspNetCore.App meta package dll files.

vkagarwal 1 Reputation point

2021-07-15T19:01:35.58+00:00

I don't agree with you. I created 2 projects from scratch, both are class library and .net core 3.1 based projects.

Both project's project file contains this

<PropertyGroup>
<TargetFramework>netcoreapp3.1</TargetFramework>
</PropertyGroup>
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