“IServiceCollection”不包含“CustomMethod”的定义，并且没有可访问的扩展方法“CustomMethod”

Question

我将代码放在单独的扩展方法中，但 ide 没有看到它。我收到下一个错误

'IServiceCollection' does not contain a definition for 'AddSwagger' and no accessible extension method 'AddSwagger' accepting a first argument of type 'IServiceCollection' could be found (are you missing a using directive or an assembly reference?)

可能是什么原因？

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

        builder.Services.AddControllers();
        builder.Services.AddEndpointsApiExplorer();
        builder.Services.AddSwagger();
        builder.Services.AddProblemDetails();

        ...
    }

    public static IServiceCollection AddSwagger(this IServiceCollection services)
    {
        return services.AddSwaggerGen(options =>
        {
            options.AddSecurityDefinition("oauth2", new OpenApiSecurityScheme
            {
                Description = "Standard Authorization header using the Bearer scheme (\"Bearer {token}\")",
                In = ParameterLocation.Header,
                Name = "Authorization",
                Type = SecuritySchemeType.ApiKey
            });

            options.OperationFilter<SecurityRequirementsOperationFilter>();
        });
    }
}

如果我将该方法移至另一个类，那么一切都会正常。为什么？

Answer 1

对于扩展方法，包含它的类也必须标记为静态。有关更多信息，请查看此 - 如何实现和调用自定义扩展方法