https://github.com/ieuanwalker/appsettings
Automatically generates the registration code for IOptions and can optionally validate them on startup using fluent validation.
https://github.com/ieuanwalker/appsettings
config configuration csharp dotnet settings source-generator
Last synced: 4 months ago
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Automatically generates the registration code for IOptions and can optionally validate them on startup using fluent validation.
- Host: GitHub
- URL: https://github.com/ieuanwalker/appsettings
- Owner: IeuanWalker
- License: mit
- Created: 2025-06-19T18:38:38.000Z (about 1 year ago)
- Default Branch: master
- Last Pushed: 2025-06-20T15:45:31.000Z (about 1 year ago)
- Last Synced: 2025-06-20T16:10:56.003Z (about 1 year ago)
- Topics: config, configuration, csharp, dotnet, settings, source-generator
- Language: C#
- Homepage:
- Size: 409 KB
- Stars: 1
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project
README
# AppSettings [](https://www.nuget.org/packages/IeuanWalker.AppSettings) [](https://www.nuget.org/packages/IeuanWalker.AppSettings) [](https://opensource.org/licenses/MIT)
Automatically generates the registration code for IOptions and can validate them on startup using [DataAnnotations](https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration/options?view=aspnetcore-9.0#options-validation) or [fluent validation](https://docs.fluentvalidation.net/en/latest/).
## How to use it?
1. Install the [NuGet package](https://www.nuget.org/packages/IeuanWalker.AppSettings) into your project.
```
Install-Package IeuanWalker.AppSettings
```
2. Inherit the `IAppSettings` interface onto the class that models your IOptions
```csharp
public class ConfirmationEmailSettings : IAppSettings
{
public required string Subject { get; set; }
}
```
3. Register the app settings
> Once `IAppSettings` has been added to a class in your project, several extension methods will automatically be created.
> The extension method name convention is AddAppSettingsFrom + your assembly name, and the namespace is your assembly name.
3.1 An extension method for `IServiceCollection` is created for all project types by default
```csharp
builder.Services.AddAppSettingsFromApiProjectNestedClassLibrary(builder.Configuration);
```
3.2 If your project is a backend/blazor project, then it will also have an extension method for `IHostApplicationBuilder`, allowing you to easily chain the registration in your progam.cs
```csharp
builder.AddAppSettingsFromApiProject();
```
3.3 If it's a MAUI project, it will also have an extension method for `MauiAppBuilder`, allowing you to easily chain the registration in your MauiProgam.cs
```csharp
builder.AddAppSettingsFromMauiProject();
```
## Section name
By default, it maps the IOptions model to the section name based on the name of the model.
For example, the following model -
```csharp
public class ConfirmationEmailSettings : IAppSettings
{
public required string Subject { get; set; }
}
```
Would automatically map to the following app setting section -
```json
{
"ConfirmationEmailSettings": {
"Subject": "Test subject"
}
}
```
If your model name and configuration section don't match or you want to bind a nested configuration, you can override this within your model by using the `SectionName` attribute
```csharp
[SectionName("ConfirmationEmail")]
public class ConfirmationEmailSettings : IAppSettings
{
public required string Subject { get; set; }
}
```
```csharp
[SectionName("NestedConfiguration:ConfirmationEmail")]
public class ConfirmationEmailSettings : IAppSettings
{
public required string Subject { get; set; }
}
```
## Validation
You can perform validation on startup using DataAnnotations or FluentValidation.
### DataAnnotation
All you need to do is add a DataAnnotation attribute onto any property
```csharp
public class ConfirmationEmailSettings : IAppSettings
{
[MinLength(5)]
public required string Subject { get; set; }
}
```
### FluentValidation
To use FluentValidation you need to create an `AbstractValidator` for your app settings model and add that validator to the `IAppSettings` inheritance.
```csharp
public class ConfirmationEmailSettings : IAppSettings
{
public required string Subject { get; set; }
}
sealed class ConfirmationEmailSettingsValidator : AbstractValidator
{
public ConfirmationEmailSettingsValidator()
{
RuleFor(x => x.Subject)
.NotEmpty()
.MinimumLength(5);
}
}
```
## Use FluentValidation without the source generator
You can use FluentValidation without the source generator by not inheriting from `IAppSettings` and using the extension method
```csharp
public class ConfirmationEmailSettings
{
public required string Subject { get; set; }
}
sealed class ConfirmationEmailSettingsValidator : AbstractValidator
{
public ConfirmationEmailSettingsValidator()
{
RuleFor(x => x.Subject)
.NotEmpty()
.MinimumLength(5);
}
}
```
In your startup -
```csharp
services.AddScoped, ConfirmationEmailSettingsValidator>();
services.AddOptions()
.Configure(options => configuration.GetSection("FluentValidationWithValidationButNoSectionNameSettings").Bind(options))
.ValidateFluentValidation()
.ValidateOnStart();
```
# What does the error look like?
If something fails validation as the application starts up, you will get an exception explaining the exact issue -
# What does the generated code look like?
The generated code is just standard C#/ .NET APIs -
> Left is the AppSettings model, Right is the generated code
# Considerations
I do not recommend adding validation to a MAUI project as it can/ will slow startup. To prevent validation, add the `DontValidate` attribute above your class.
```csharp
[DontValidate]
public class MobileAppSettings : IAppSettings
{
public required string Subject { get; set; }
}
```