ReHackt.Extensions.Options.Validation

Extends OptionsBuilder<T> and IServiceCollection with nested data annotations validation and eager validation on start.

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TL;DR

1. Create your options class(es)
2. Decorate your options with data annotations
3. Call ConfigureAndValidate<T>(Action<T> configureOptions) on your IServiceCollection

ConfigureAndValidate will configure your options (calling the base Configure method), but will also check that the built configuration respects the data annotations, otherwise an OptionsValidationException (with details) is thrown as soon as the application is started. No misconfiguration surprise at runtime!

Example

// Startup configuration

public void ConfigureServices(IServiceCollection services)
{
    services.ConfigureAndValidate<ApplicationOptions>(options => _configuration.Bind(options));
    
    ...
}


// Options classes

public class ApplicationOptions
{
    [Required]
    public EmailOptions Email { get; set; }

    public SecurityOptions Security { get; set; }

    ...
}

public class EmailOptions
{
    [Required]
    public string Host { get; set; }

    [Required]
    public int Port { get; set; }

    public bool UseSsl { get; set; }

    ...
}

public class SecurityOptions
{
    [Range(8, int.MaxValue, ErrorMessage = "The {0} must be greater than {1}.")]
    public int PasswordMinLength { get; set; } = 8;

    ...
}

Use

ServiceCollection extension

ConfigureAndValidate

services.ConfigureAndValidate<TOptions>(configureOptions)

Is syntactic sugar for

services
    .AddOptions<TOptions>()
        .Configure(configureOptions)
        .ValidateDataAnnotationsRecursively()
        .ValidateOnStart()   // or ValidateEagerly()
        .Services

OptionsBuilder extensions

ValidateDataAnnotationsRecursively

This method register this options instance for validation of its DataAnnotations at the first dependency injection. Nested objects are supported.

ValidateOnStart (or ValidateEagerly in previous versions)

This method validates this options instance at application startup rather than at the first dependency injection.

ConfigureAndValidate

optionsBuilder.ConfigureAndValidate<TOptions>(configureOptions)

Is syntactic sugar for

optionsBuilder
    .Configure(configureOptions)
    .ValidateDataAnnotationsRecursively()
    .ValidateOnStart()   // or ValidateEagerly()