The Options pattern is a design pattern in ASP.NET Core that enables you to access configuration values in a strongly typed manner. Instead of retrieving configuration values as strings and manually converting them to the appropriate types, you define POCO (Plain Old CLR Object) classes that represent the structure of your configuration sections. These classes, known as “options” classes, make your configuration code more readable, maintainable, and less error-prone.
Benefits of the Options Pattern Strongly Typed Access: Access your configuration values directly as properties of your options classes, eliminating the need for manual type conversions and reducing the risk of runtime errors. IntelliSense Support: Get code completion and type checking in your IDE when working with your configuration settings. Validation: You can easily add validation logic to your options classes to ensure that configuration values are valid. Clean Separation: Keep your configuration settings separate from your business logic, improving the overall organization of your code.
When to Use the Options Pattern Related Settings: When you have groups of related configuration settings that logically belong together (e.g., database connection settings, email settings, feature flags). Strongly Typed Access: When you want to work with your configuration values in a type-safe manner. Validation: When you want to add validation logic to ensure your configuration values are valid.
How to Implement the Options Pattern Create an Options Class: Define a class that mirrors the structure of your configuration section. Make sure the property names match the keys in your configuration file. public class EmailOptions { public string SmtpServer { get; set; } = string.Empty; public int SmtpPort { get; set; } = 25; public string SenderEmail { get; set; } = string.Empty; public string SenderPassword { get; set; } = string.Empty; } Register the Options: In your Program.cs (or Startup.cs in older versions), register your options class using the Configure<T> extension method on IServiceCollection: builder.Services.Configure<EmailOptions>(builder.Configuration.GetSection(“Email”)); This tells the DI container to bind the settings in the Email section of your configuration to an instance of EmailOptions. Inject IOptions<T>: Inject the IOptions<T> interface into your controllers or services to access the bound options: public class EmailService : IEmailService { private readonly EmailOptions _options;
public EmailService(IOptions<EmailOptions> options) { _options = options.Value; }
// … use _options.SmtpServer, _options.SmtpPort, etc. … }
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