我按照这个教程进行操作,一切都很好,直到我修改了我的DbContext
,添加了一个额外的构造函数。现在我遇到了解析问题,不确定该怎么办来修复它。是否有一种简单的方法来强制使用无参构造函数,或者我是以错误的方式进行的?
DbContext
有两个构造函数:
public class DashboardDbContext : DbContext
{
public DashboardDbContext() : base("DefaultConnection") { }
public DashboardDbContext(DbConnection dbConnection, bool owns)
: base(dbConnection, owns) { }
}
SiteController
构造函数:
private readonly IDashboardRepository _repo;
public SiteController(IDashboardRepository repo)
{
_repo = repo;
}
存储库:
DashboardDbContext _context;
public DashboardRepository(DashboardDbContext context)
{
_context = context;
}
UnityResolver
代码:
public class UnityResolver : IDependencyResolver
{
private readonly IUnityContainer _container;
public UnityResolver(IUnityContainer container)
{
_container = container;
}
public object GetService(Type serviceType)
{
try
{
return _container.Resolve(serviceType);
}
catch (ResolutionFailedException)
{
return null;
}
}
public IEnumerable<object> GetServices(Type serviceType)
{
try
{
return _container.ResolveAll(serviceType);
}
catch (ResolutionFailedException)
{
return new List<object>();
}
}
public IDependencyScope BeginScope()
{
var child = _container.CreateChildContainer();
return new UnityResolver(child);
}
public void Dispose()
{
_container.Dispose();
}
}
WebApi配置文件:
var container = new UnityContainer();
container.RegisterType<IDashboardRepository, DashboardRepository>(new HierarchicalLifetimeManager());
config.DependencyResolver = new UnityResolver(container);
WebApi调用出现错误:
System.InvalidOperationException:尝试创建类型为“SiteController”的控制器时发生错误。请确保该控制器具有无参数的公共构造函数。
at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)
at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)
at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsyncCore(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__0.MoveNext()
InnerException: System.ArgumentException: 类型 'Dashboard.Web.Controllers.SiteController' 没有默认构造函数。
at System.Linq.Expressions.Expression.New(Type type)
at System.Web.Http.Internal.TypeActivator.Create[TBase](Type instanceType)
at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)
at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)
教程很好,直到我添加第二个构造函数之后才出现了问题。
SiteController
中添加一个无参数的构造函数,而不是在DashboardDbContext
中。 - Neil SmithSiteController
的构造函数吗? - Neil SmithDbContext
注入到仓储中了? - Neil Smith