# Web APIs

{% embed url="https://dotnet.microsoft.com/en-us/apps/aspnet/apis" %}

ASP.NET Core supports creating web APIs using controllers or using minimal APIs.

* _Controllers_ in an API project are classes that derive from `ControllerBase`.
* _Minimal APIs_ define endpoints with logical handlers in lambdas or methods.

{% tabs %}
{% tab title="Using Controllers" %}
{% code title="Program.cs" %}
```csharp
namespace APIWithControllers;

public class Program {
    public static void Main(string[] args) {
        var builder = WebApplication.CreateBuilder(args);

        builder.Services.AddControllers();
        var app = builder.Build();

        app.UseHttpsRedirection();

        app.MapControllers();

        app.Run();
    }
}
```
{% endcode %}

```csharp
using Microsoft.AspNetCore.Mvc;

namespace APIWithControllers.Controllers;

[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase {
    private static readonly string[] Summaries = new[] {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };

    private readonly ILogger<WeatherForecastController> _logger;

    public WeatherForecastController(ILogger<WeatherForecastController> logger) {
        _logger = logger;
    }

    [HttpGet(Name = "GetWeatherForecast")]
    public IEnumerable<WeatherForecast> Get() {
        return Enumerable.Range(1, 5).Select(index => new WeatherForecast {
            Date = DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
            TemperatureC = Random.Shared.Next(-20, 55),
            Summary = Summaries[Random.Shared.Next(Summaries.Length)]
        })
        .ToArray();
    }
}
```
{% endtab %}

{% tab title="Using Minimal APIs" %}
{% code title="Program.cs" %}
```csharp
namespace MinimalAPI;

public class Program {
    public static void Main(string[] args) {
        var builder = WebApplication.CreateBuilder(args);

        var app = builder.Build();

        app.UseHttpsRedirection();

        var summaries = new[] {
            "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
        };

        app.MapGet("/weatherforecast", (HttpContext httpContext) => {
            var forecast = Enumerable.Range(1, 5).Select(index =>
                new WeatherForecast {
                    Date = DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
                    TemperatureC = Random.Shared.Next(-20, 55),
                    Summary = summaries[Random.Shared.Next(summaries.Length)]
                })
                .ToArray();
            return forecast;
        });

        app.Run();
    }
}
```
{% endcode %}
{% endtab %}

{% tab title="WeatherForecast.cs" %}
```csharp
public class WeatherForecast {
    public DateOnly Date { get; set; }
    public int TemperatureC { get; set; }
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
    public string? Summary { get; set; }
}
```
{% endtab %}
{% endtabs %}

## Resources

{% embed url="https://youtube.com/playlist?list=PLdo4fOcmZ0oVjOKgzsWqdFVvzGL2_d72v" %}

{% embed url="https://learn.microsoft.com/en-us/aspnet/web-api/" %}
