Overview

The MinimalApiEndpointBase library simplifies the organization, registration, and mapping of minimal API endpoints in your ASP.NET Core applications. It uses an abstract base class for endpoint logic, making your API endpoints modular and testable.

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Key Components

1. MinimalApiEndpointBase

This is the abstract base class that your API endpoints should inherit from. It provides:

• Properties:

  • Application: The WebApplication instance for the current application.
  • Services: An IServiceProvider instance for dependency injection.

• Abstract Method:

  • HandleEndpoint(IEndpointRouteBuilder endpoint): Must be implemented by derived classes to define endpoint routing and logic.

• Method:

  • Initialize(WebApplication app): Used internally to associate the base class with the current WebApplication.

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2. Extension Methods

AddMinimalApiEndpoints(IServiceCollection services)

• Scans all loaded assemblies to find implementations of MinimalApiEndpointBase.
• Registers these implementations as services in the DI container.

MapMinimalApiEndpoints(WebApplication app)

• Resolves all registered MinimalApiEndpointBase services.
• Calls their Initialize and HandleEndpoint methods to configure routes within the application.

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Setup and Usage

Follow these steps to integrate and use the library in your ASP.NET Core application:

1. Create an Endpoint Class

Define an endpoint by inheriting from MinimalApiEndpointBase:

public class WeatherEndpoint : MinimalApiEndpointBase
{
    public override void HandleEndpoint(IEndpointRouteBuilder endpoint)
    {
        endpoint.MapGet("/weather", async context =>
        {
            var forecast = new[] { "Sunny", "Cloudy", "Rainy" };
            await context.Response.WriteAsJsonAsync(forecast);
        });
    }
}

2. Register Endpoints in Dependency Injection

In the Program.cs file, register the endpoints by calling AddMinimalApiEndpoints:

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddMinimalApiEndpoints();

var app = builder.Build();

3. Map Endpoints to the WebApplication

Use MapMinimalApiEndpoints to map all registered endpoints during the application configuration:

// Configure the HTTP request pipeline.
app.MapMinimalApiEndpoints();

app.Run();

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Example Application

Here’s a complete example of an application using the library:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using System;

public class WeatherEndpoint : MinimalApiEndpointBase
{
    public override void HandleEndpoint(IEndpointRouteBuilder endpoint)
    {
        endpoint.MapGet("/weather", async context =>
        {
            var forecast = new[] { "Sunny", "Cloudy", "Rainy" };
            await context.Response.WriteAsJsonAsync(forecast);
        });
    }
}

var builder = WebApplication.CreateBuilder(args);

// Register all endpoint implementations.
builder.Services.AddMinimalApiEndpoints();

var app = builder.Build();

// Map endpoints to routes.
app.MapMinimalApiEndpoints();

app.Run();

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Advanced Features

Dynamic Dependency Injection

Use the Services property in your endpoint implementation to resolve dependencies:

public class GreetingEndpoint : MinimalApiEndpointBase
{
    public override void HandleEndpoint(IEndpointRouteBuilder endpoint)
    {
        endpoint.MapGet("/greet", async context =>
        {
            var logger = Services.GetRequiredService<ILogger<GreetingEndpoint>>();
            logger.LogInformation("Greet endpoint called");

            await context.Response.WriteAsync("Hello, world!");
        });
    }
}

Access to Application

The Application property provides access to the WebApplication instance, enabling you to perform application-level configurations or access global middleware and services:

public class CustomMiddlewareEndpoint : MinimalApiEndpointBase
{
    public override void HandleEndpoint(IEndpointRouteBuilder endpoints)
    {
        Application.Use(async (context, next) =>
        {
            // Custom logic before passing to the next middleware
            context.Response.Headers.Add("X-Custom-Header", "HelloFromMiddleware");
            await next();
        });

        endpoints.MapGet("/custom-middleware", async context =>
        {
            await context.Response.WriteAsync("Middleware is applied!");
        });
    }
}

Read form Configuration

You can use the Configuration property to access application settings, such as those defined in appsettings.json, environment variables, or other sources.

public class GreetingEndpoint : MinimalApiEndpointBase
{
    public override void HandleEndpoint(IEndpointRouteBuilder endpoint)
    {
        endpoint.MapGet("/greet", async context =>
        {
            var greetingMessage = Configuration["Greeting"]; // Access configuration setting
            await context.Response.WriteAsync(greetingMessage);
        });
    }
}