Minimal API：静态类中如何注入并使用ILogger

报错原因 #

C#禁止将静态类型作为泛型类型参数使用，因此ILogger<PingEndpoints>的写法不合法（PingEndpoints是静态类）。以下是几种无需重构整个类结构的解决办法：

方案一：在扩展方法中预获取Logger并传递 #

保留静态类和静态方法，在端点注册时从服务容器获取指定类别的Logger，通过闭包传递给处理方法：

public static class PingEndpoints
{
    public static void Endpoints(this WebApplication application)
    {
        // 针对PingEndpoints创建Logger
        var logger = application.Services.GetRequiredService<ILoggerFactory>()
            .CreateLogger(typeof(PingEndpoints));
        var group = application.MapGroup("ping");

        // 通过闭包将logger传入PingMethod
        group.MapGet("", () => PingMethod(logger));
    }

    internal static IResult PingMethod(ILogger logger)
    {
        try
        {
            logger.LogInformation("Test log");
            var pingInfo = new PingInfo(DateTime.UtcNow, "Ping successful");
            return Results.Ok(pingInfo);
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "Ping request failed");
            return Results.StatusCode(StatusCodes.Status500InternalServerError);
        }
    }
}

方案二：注入ILoggerFactory并创建指定Logger #

保持端点方法的参数注入模式，直接注入ILoggerFactory，在方法内部创建针对静态类的Logger：

public static class PingEndpoints
{
    public static void Endpoints(this WebApplication application)
    {
        var group = application.MapGroup("ping");
        group.MapGet("", PingMethod);
    }

    internal static IResult PingMethod([FromServices] ILoggerFactory loggerFactory)
    {
        var logger = loggerFactory.CreateLogger(typeof(PingEndpoints));
        try
        {
            logger.LogInformation("Test log");
            var pingInfo = new PingInfo(DateTime.UtcNow, "Ping successful");
            return Results.Ok(pingInfo);
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "Ping request failed");
            return Results.StatusCode(StatusCodes.Status500InternalServerError);
        }
    }
}

方案三：将静态类改为非静态类（可选） #

如果允许调整类的结构，将静态类改为非静态类，使用构造注入Logger，更符合依赖注入的常规实践：

public class PingEndpoints
{
    private readonly ILogger<PingEndpoints> _logger;

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

    public void Endpoints(this WebApplication application)
    {
        var group = application.MapGroup("ping");
        group.MapGet("", PingMethod);
    }

    internal IResult PingMethod()
    {
        try
        {
            _logger.LogInformation("Test log");
            var pingInfo = new PingInfo(DateTime.UtcNow, "Ping successful");
            return Results.Ok(pingInfo);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Ping request failed");
            return Results.StatusCode(StatusCodes.Status500InternalServerError);
        }
    }
}

对应的Program.cs注册逻辑：

var builder = WebApplication.CreateBuilder(args);

// 注册PingEndpoints为服务
builder.Services.AddTransient<PingEndpoints>();

var app = builder.Build();

// 获取实例并注册端点
var pingEndpoints = app.Services.GetRequiredService<PingEndpoints>();
pingEndpoints.Endpoints(app);

app.Run();

内容的提问来源于stack exchange，提问作者Hardipsinh Jadeja