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NotNot.AppSettings

ReadMe.md

NotNot.AppSettings

Automatically create strongly typed C# settings objects from AppSettings.json. Uses Source Generators.

Includes a simple deserialization helper for when you are using Dependency Injection, or not.

Table of Contents

Getting Started

  1. Add an appsettings.json file to your project (make sure it's copied to the output).
  2. Install this nuget package NotNot.AppSettings.
  3. Build your project
  4. Use the generated AppSettings class in your code. (See the example section below).

How it works

During your project's build process, NotNot.AppSettings will parse the appsettings*.json in your project's root folder. These files are all merged into a single schema. Using source-generators it then creates a set of csharp classes that matches each node in the json hierarchy.

After building your project, an AppSettings class contains the strongly-typed definitions, and an AppSettingsBinder helper/loader util will be found under the {YourProjectRootNamespace}.AppSettingsGen namespace.

Example

appsettings.json

{
  "Hello": {
	"World": "Hello back at you!"
  }
}

Program.cs

using ExampleApp.AppSettingsGen;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace ExampleApp;
public class Program
{ 
   public static async Task Main(string[] args)
   {
      {
         Console.WriteLine("NON-DI EXAMPLE");
                  
         var appSettings = ExampleApp.AppSettingsGen.AppSettingsBinder.LoadDirect();
         Console.WriteLine(appSettings.Hello.World);         
      }
      {
         Console.WriteLine("DI EXAMPLE");

         HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);
         builder.Services.AddSingleton<IAppSettingsBinder, AppSettingsBinder>();
         var app = builder.Build();
         var appSettings = app.Services.GetRequiredService<IAppSettingsBinder>().AppSettings;
         Console.WriteLine(appSettings.Hello.World);
      }
   }
}

See the ./NotNot.AppSettings.Example folder in the repository for a fully buildable version of this example.

Troubleshooting / Tips

How to access the generated classes from external code?

To prevent namespace collisions with other projects, the generated classes are internal by default. If you need to access it from another project, the best solution is to make a wrapper class in the project that uses the generated code. Alternatively, you can make the generated code public:

  • v2.0.0 and later: you can add the following to your .csproj file:
	<PropertyGroup>
		<NotNot_AppSettings_GenPublic>true</NotNot_AppSettings_GenPublic>
	</PropertyGroup>
  • v1.x and earlier: The AppSettings class is public by default.

How to extend the generated AppSettings class?

You can extend any/all of the generated code by creating a partial class in the same namespace.

Some settings not being loaded (value is NULL). Or: My appSettings.Development.json file is not loaded

Ensure the proper environment variable is set. For example, The appSettings.Development.json file is only loaded when the ASPNETCORE_ENVIRONMENT or DOTNET_ENVIORNMENT environment variable is set to Development.

Intellisense not working for AppSettings class

A strongly-typed AppSettings (and sub-classes) is recreated every time you build your project. This may confuse your IDE and you might need to restart it to get intellisense working again.

Why are some of my nodes typed as object?

Under some circumstances, the type of a node's value in appsettings.json would be ambiguous, so object is used:

  • If the value is null or undefined
  • If the value is a POJO/Array/primitive in one appsettings file, and a different one of those three in another.

Tip: Backup generated code in your git repository

Add this to your .csproj to have the code output to ./Generated and have it be ignored by your project. This way you can check it into source control and have a backup of the generated code in case you need to stop using this package.

<!--output the source generator build files-->
<Target Name="DeleteFolder" BeforeTargets="PreBuildEvent">
	<RemoveDir Directories="$(CompilerGeneratedFilesOutputPath)" />
</Target>	
<PropertyGroup>
	<EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
	<CompilerGeneratedFilesOutputPath>Generated</CompilerGeneratedFilesOutputPath>
</PropertyGroup>
<ItemGroup>
	<!--Exclude the output of source generators from the compilation-->
	<Compile Remove="$(CompilerGeneratedFilesOutputPath)/**" />
</ItemGroup>

Contribute

  • If you find value from this project, consider sponsoring.

Local Development (Reference .csproj, not Nuget)

  • Add OutputItemType="Analyzer" ReferenceOutputAssembly="false" to the <ProjectReference/>
  • beware when attempting to update nuget packages, it will likely break the Source Generator. Default to just leaving them as is, unless you want to spend time troubleshooting sourcegen thrown exceptions.

Nuget

  • current version is set via MinVer, which matches the repo git tags.
  • read the repo's Contrib/ folder for more info.

Acknowledgments

License: MPL-2.0

A summary from TldrLegal:

MPL is a copyleft license that is easy to comply with. You must make the source code for any of your changes available under MPL, but you can combine the MPL software with proprietary code, as long as you keep the MPL code in separate files. Version 2.0 is, by default, compatible with LGPL and GPL version 2 or greater. You can distribute binaries under a proprietary license, as long as you make the source available under MPL.

In brief: You can basically use this project however you want, but all changes to it must be open sourced.

Notable Changes

  • 2.0.0 : generated code is now internal by default. Make it public by adding <NotNot_AppSettings_GenPublic>true</NotNot_AppSettings_GenPublic> to your .csproj
  • 1.2.1 : improve doc for missing appSettings.json, handle projects with blank default namespace. move to new repository.
  • 1.1.1 : make the nuget package <PrivateAsset> so only the project that directly references it uses it.
    • (needed for example: test projects)
  • 1.0.0 : polish and readme tweaks. Put a fork in it, it's done!
  • 0.12.0 : change appsettings read logic to use "AdditionalFiles" workflow instead of File.IO
  • 0.10.0 : Initial Release.