How to Share a file between multiple projects in Visual Studio

This method is commonly used for configuration or source files.

Here’s how to link an appsettings.json file:

1. In the project where you want to link the file, right-click on the project and select Add > Existing Item.
2. Navigate to the desired file.
3. Click the dropdown arrow next to the Add button and select Add As Link.

You’ll now see the file appear twice: once in its original location and once as a linked file in the other project.

These files are logically linked to a single physical file. Any edits made to the file in one project will reflect in all linked instances. You can identify linked files by the small arrow on their icon.

Copying Linked Content Files to the Build Directory

To ensure that a linked content file (like appsettings.json) is copied to the build directory, follow these steps:

1. Right-click the linked appsettings.json file and select Properties.
2. Set Copy To Output Directory to Copy if newer.

This configuration will ensure that the linked file is copied during the build process.

Linked File Configuration in .csproj

Here’s how a linked file appears in the .csproj file:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <Content Include="..\WebAPI\appsettings.json" Link="appsettings.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </Content>
  </ItemGroup>

</Project>

In this example, pay attention to these points:

• Include="..\WebAPI\appsettings.json" specifies the relative path to the physical file.
• Link="appsettings.json" denotes the logical name of the linked file in the project.

You can assign a different logical name than the physical file, but keep in mind that this name will be used when copying to the output directory.

For instance, if you set Link="test.json", the appsettings.json file will be copied as test.json.

If you wish to add linked files to new projects without using the UI, you can copy and paste the linked file XML into the new .csproj file, ensuring the relative path (Include="…") is accurate for your new project.

The location of the physical file depends on personal preference, with two common approaches:

1. Place the physical file in one project directory and create links in all other projects.
2. Store the physical file in the solution directory, add it at the solution level, and create links in all projects.