Consuming an API with HttpClient

Connecting to C#

If you want to read a file on your computer, you use File.ReadAllText(). If you want to fetch data from the internet, you use HttpClient.

Example 1: Making a GET Request

using System.Net.Http;
using System.Threading.Tasks;

public class ApiConsumer
{
    public async Task GetWeatherData()
    {
        // 1. Create the phone (HttpClient)
        using HttpClient client = new HttpClient();
        
        // 2. Dial the number (The API URL)
        string url = "https://api.open-meteo.com/v1/forecast?latitude=52.52&longitude=13.41¤t_weather=true";
        
        // 3. Make the call and wait for the answer
        HttpResponseMessage response = await client.GetAsync(url);
        
        // 4. Ensure the call was successful (Status 200)
        response.EnsureSuccessStatusCode();
        
        // 5. Read the JSON text answer
        string jsonResponse = await response.Content.ReadAsStringAsync();
        
        Console.WriteLine(jsonResponse);
    }
}

Example 2: The Modern Way (Deserializing directly)

Instead of reading a raw string, you can immediately convert the JSON into a C# object using ReadFromJsonAsync.

// Inside an async method:
var weatherData = await client.GetFromJsonAsync<WeatherForecast>(url);

Console.WriteLine($"Current Temp: {weatherData.CurrentWeather.Temperature}");