API Reference
This section provides a comprehensive reference to the core APIs used in .NET Web Fundamentals. Understanding these classes and methods is crucial for building robust and efficient web applications.
Core Classes and Interfaces
Microsoft.AspNetCore.Http.HttpRequest
Represents an incoming HTTP request. This object provides access to request details such as headers, query parameters, body, and more.
Properties:
Method- Gets the HTTP method (e.g., GET, POST, PUT, DELETE).
Path- Gets the path of the request URL.
Query- Gets the collection of query parameters.
Headers- Gets the collection of HTTP headers.
Body- Gets the request body as a stream.
Microsoft.AspNetCore.Http.HttpResponse
Represents an outgoing HTTP response. This object allows you to set status codes, headers, and write to the response body.
Properties:
StatusCode- Gets or sets the HTTP status code.
Headers- Gets the collection of HTTP response headers.
Body- Gets or sets the response body as a stream.
Methods:
Redirect(string url)- Sends a redirect response to the client.
WriteAsync(byte[] data)- Writes a byte array to the response body.
Microsoft.AspNetCore.Mvc.ControllerBase
The base class for all controllers in an ASP.NET Core application. Provides common functionality for handling HTTP requests and returning responses.
Common Methods:
Ok()- Returns an OK (200) response.
NotFound()- Returns a Not Found (404) response.
BadRequest()- Returns a Bad Request (400) response.
Ok(object value)- Returns an OK response with a value.
Microsoft.AspNetCore.Mvc.IActionResult
Represents the result of an action method. Implementations define how the action result is executed against the current HTTP context.
Common API Patterns
Request Handling
You typically access request information through the HttpContext object, which is available in controllers and middleware.
using Microsoft.AspNetCore.Http;
public class ExampleMiddleware
{
private readonly RequestDelegate _next;
public ExampleMiddleware(RequestDelegate next)
{
_next = next;
}
public async Task InvokeAsync(HttpContext context)
{
var requestPath = context.Request.Path;
var httpMethod = context.Request.Method;
// Process request...
await _next(context);
// Process response...
}
}
Response Generation
Controllers return implementations of IActionResult to define the response.
using Microsoft.AspNetCore.Mvc;
[ApiController]
[Route("[controller]")]
public class ItemsController : ControllerBase
{
[HttpGet("{id}")]
public IActionResult GetItem(int id)
{
if (id <= 0)
{
return BadRequest("Item ID must be positive.");
}
// Simulate fetching item...
var item = new { Id = id, Name = $"Item {id}" };
if (item == null)
{
return NotFound($"Item with ID {id} not found.");
}
return Ok(item); // Returns HTTP 200 OK with the item object
}
}
Key Libraries and Namespaces
Microsoft.AspNetCore.Http: For request and response manipulation.Microsoft.AspNetCore.Mvc: For building controllers and action results.Microsoft.Extensions.DependencyInjection: For managing dependency injection.Microsoft.Extensions.Configuration: For accessing application configuration.