Cannot copy folder with nuget package in .net core - visual-studio

Question

I Create a NuGet package and install into another project. but don't copy a file into the location project. only my file reference to NuGet package and I change the code, The package also changes! I want to copy the package to the target project.
<?xml version="1.0"?>
<package>
<metadata minClientVersion="3.3.0">
<id>MyPackage</id>
<version>1.0.0</version>
<authors>Meysam</authors>
<owners>Meysam</owners>
<requireLicenseAcceptance>false</requireLicenseAcceptance>
<description>Package description</description>
<releaseNotes>Summary of changes made in this release of the package.</releaseNotes>
<copyright>Copyright 2018</copyright>
<tags>Tag1 Tag2</tags>
<contentFiles>
<files include="cs/*.*/**" buildAction="Compile" />
</contentFiles>
</metadata>
<files>
<file src="ConsoleApp1\CustomClass\CustomClass.cs" target="contentFiles\cs\any\CustomClass" />
</files>
</package>

Answer 1

Copying files into the project that uses a nuget package is only supported when using packages.config, which isn't supported by SDK-style projects, which are required for .NET Core projects. As your screenshots show, contentFiles in PackageReferences projects are included at build time. The little arrow icon in the bottom right corner of the C# and folder icons you pointed to in your screenshot are visual indicators that the file and folder are different to the other files and folders in your project. In fact, that little icon overlay is similar to what Windows adds for shortcuts, so if you understand a shortcut is a file that "points to" another file, it should make sense that these are shortcuts to files outside your project, but are included as part of your project.
Anyway, it's working as designed.
You'll need to find another way to do whatever you want, but you didn't describe why you're trying to include a file in the project that references your package, so I can't give direct advice. My best advice, if you are experienced with ASP.NET and ASP.NET Core is think about how ASP.NET used to read a lot of settings directly from web.config, but ASP.NET Core instead uses a builder pattern, so that users are not forced to store settings in web.config and can store settings anywhere they want. If what you're doing is similar, your package users will have a better experience if you provide them with a configuration builder that they can override, rather than having a file in their project that they must edit and gets overwritten every time they upgrade to a new version of your package.

Answer 2

Cannot copy folder with nuget package in .net core
Yes, just like zivkan said:
Copying files into the project that uses a nuget package is only
supported when using packages.config
But, we could use a workaround to resolve this issue. We could add a copy task in the xx.targets file, and set this file in the \build folder in the .nuspec file.
The content of mypackage.targets file:
<Target Name="CopyFile" AfterTargets="AfterBuild">
<ItemGroup>
<CopyFiles Include="$(NuGetPackageRoot)\mypackage\4.0.0\cs\*.*\**" />
</ItemGroup>
<Copy
SourceFiles="#(CopyFiles)"
DestinationFolder="$(ProjectDir)"
/>
</Target>
And the .nuspec file:
<file src="xxx\xxx\mypackage.targets" target="build" />
Hope this helps.