HttpContext holds the information associated with one HTTP request and its response. When a request arrives, ASP.NET Core’s web server creates the context from the incoming data and passes it into the application. Code handling the request uses it to decide what response to produce. section 3.1 section 1.4.2
Think of it as a storage box that travels with the request:
- It starts with request details supplied by the web server and can hold request-specific services, loaded data, and errors. section 3.1
- Middleware can read or change it. Each component sees changes made earlier in the pipeline; after a response is generated, components can inspect or modify it on the way back. section 4.1 section 4.2
- A minimal API handler can receive HttpContext as a parameter. For common needs, HttpRequest and HttpResponse parameters provide narrower access to its Request and Response properties. section 7.6.1
A small middleware decision
A middleware component can check context.Request.Path. If the path starts with /ping, it sets a plain-text response and writes “pong”; otherwise, it passes the same context to the next middleware. For an ordinary application route, prefer endpoint routing over directly inspecting paths in middleware. section 36.1
Listing 36.1 StatusMiddleware to be tested, which returns a "pong" response
public class StatusMiddleware
{
private readonly RequestDelegate _next; #1
public StatusMiddleware(RequestDelegate next) #1
{
_next = next;
}
public async Task Invoke(HttpContext context) #2
{
if(context.Request.Path.StartsWithSegments("/ping")) #3
{ #3
context.Response.ContentType = "text/plain"; #3
await context.Response.WriteAsync("pong"); #3
return; #3
} #3
await _next(context); #4
}
}
The listing shows both paths through the decision: write a response and stop, or call the next RequestDelegate with the HttpContext. section 36.1
For a middleware unit test, DefaultHttpContext supplies a context you can configure. Set Request.Path to a nonmatching value, invoke the middleware, and check that it called the next RequestDelegate. Because HttpContext exposes many request and response details, such tests can become tightly coupled to the middleware implementation. section 36.1
