ASP.NET MapGet
last modified October 18, 2023
In this article we show how to map GET requests to handlers in ASP.NET.
ASP.NET is a cross-platform, high-performance, open-source framework for building modern, cloud-enabled, web applications. It is developed by Microsoft.
The HTTP GET method requests a representation of the specified resource. Requests using GET should only retrieve data.
GET requests:
- should only be used to request a resource
- parameters are displayed in the URL
- can be cached
- remain in the browser history
- can be bookmarked
- should never be used when dealing with sensitive data
- have length limits
The MapGet method adds a RouteEndpoint to the endpoint
builder that matches HTTP GET requests for the specified pattern.
ASP.NET MapGet example
The following is a simple MapGet example.
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
app.MapGet("/", () => "home page\n");
app.MapGet("/about", () => "about page\n");
app.Run("http://localhost:3000");
We map two endpoints with MapGet.
app.MapGet("/", () => "home page\n");
With MapGet, we map the lambda expression to the /
path.
app.Run("http://localhost:3000");
The application listens on port 3000.
$ curl localhost:3000 home page $ curl localhost:3000/about about page
We generate two GET requests.
$ curl localhost:3000 -X POST -i HTTP/1.1 405 Method Not Allowed Content-Length: 0 Date: Wed, 28 Sep 2022 11:33:34 GMT Server: Kestrel Allow: GET $ curl localhost:3000/about -X POST -i HTTP/1.1 405 Method Not Allowed Content-Length: 0 Date: Wed, 28 Sep 2022 11:33:39 GMT Server: Kestrel Allow: GET
However, the POST requests are not allowed.
ASP.NET MapGet example II
In the next example, we map two endpoints to local functions.
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
app.MapGet("/", homePage);
app.MapGet("/about", aboutPage);
app.Run("http://localhost:3000");
string homePage() => "home page\n";
string aboutPage() => "about page\n";
We have two endpoints.
app.MapGet("/", homePage);
app.MapGet("/about", aboutPage);
We map the two endpoints to two local functions.
using var client = new HttpClient();
var content = await client.GetStringAsync("http://localhost:3000/about");
Console.WriteLine(content);
We create a C# console application which sends a GET request to one of the
endpoints. We use the HttpClient class.
$ dotnet run about page
We run the console application and receive a response from the ASP.NET application.
In this article we have shown how to map GET requests with MapGet in ASP.NET.