asp.net-mvc – 没有注册默认实例,无法自动确定类型

发布时间：2020-12-16 03:38:23 所属栏目：asp.Net 来源：网络整理

导读：我的界面定义如下： public interface IApplicationSettings{ string LoggerName { get; } string NumberOfResultsPerPage { get; } string EmailAddress { get; } string Credential { get; }} 该接口的实现如下： public class WebConfigApplicationSettin

我的界面定义如下：

public interface IApplicationSettings
{
   string LoggerName { get; }
   string NumberOfResultsPerPage { get; }
   string EmailAddress { get; }
   string Credential { get; }
}

该接口的实现如下：

public class WebConfigApplicationSettings : IApplicationSettings
    {
        public string LoggerName
        {
            get { return ConfigurationManager.AppSettings["LoggerName"]; }
        }

        public string NumberOfResultsPerPage
        {
            get { return ConfigurationManager.AppSettings["NumberOfResultsPerPage"]; }
        }

        public string EmailAddress
        {
            get { return ConfigurationManager.AppSettings["EmailAddress"]; }
        }

        public string Credential
        {
            get { return ConfigurationManager.AppSettings["Credential"]; }
        }
    }

我还创建了一个工厂类来获取WebConfigSettings具体实现的实例,如下所示：

public class ApplicationSettingsFactory
    {
        private static IApplicationSettings _applicationSettings;

        public static void InitializeApplicationSettingsFactory(
                                      IApplicationSettings applicationSettings)
        {
            _applicationSettings = applicationSettings;
        }

        public static IApplicationSettings GetApplicationSettings()
        {
            return _applicationSettings;
        }
    }

然后我解决了依赖关系如下：

public class DefaultRegistry : Registry {

        public DefaultRegistry() {
            Scan(
                scan => {
                    scan.TheCallingAssembly();
                    scan.WithDefaultConventions();
                    scan.With(new ControllerConvention());
                });


             For<IApplicationSettings>().Use<WebConfigApplicationSettings>();

             ApplicationSettingsFactory.InitializeApplicationSettingsFactory
                                   (ObjectFactory.GetInstance<IApplicationSettings>());

        }
    }

现在,当我运行我的应用程序时,它会抛出以下异常：

Exception has been thrown by the target of an invocation.

而内在的例外是

No default Instance is registered and cannot be automatically determined for type 'Shoppingcart.Infrastructure.Configuration.IApplicationSettings'rnrnThere is no configuration specified for Shoppingcart.Infrastructure.Configuration.IApplicationSettingsrnrn1.) Container.GetInstance(Shoppingcart.Infrastructure.Configuration.IApplicationSettings)rn

我正在使用StructureMap for MVC5

解决方法

您的代码无法工作的原因是因为当您调用ObjectFactory.GetInstance< IApplicationSettings>()时,您的注册表尚未注册,因此,StructureMap的配置不完整.

我相信你要做的是以下(测试和工作)：

public class ApplicationSettingsFactory
{
    public ApplicationSettingsFactory(WebConfigApplicationSettings applicationSettings)
    {
        _applicationSettings = applicationSettings;
    }

    private static IApplicationSettings _applicationSettings;

    public IApplicationSettings GetApplicationSettings()
    {
        return _applicationSettings;
    }
}

您的注册表配置如下：

public DefaultRegistry() {

    Scan(scan => {
         scan.TheCallingAssembly();
         scan.WithDefaultConventions();
         scan.With(new ControllerConvention());
    });

    this.For<IApplicationSettings>().Use(ctx => ctx.GetInstance<ApplicationSettingsFactory>().GetApplicationSettings());

}

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!