[英]Ninject conditional binding based on parameter type
I'm using a factory to return a datasender: 我正在使用工厂返回数据库:
Bind<IDataSenderFactory>()
.ToFactory();
public interface IDataSenderFactory
{
IDataSender CreateDataSender(Connection connection);
}
I have two different implementations of datasender (WCF and remoting) which take different types: 我有两种不同的数据集实现(WCF和远程处理),它们采用不同的类型:
public abstract class Connection
{
public string ServerName { get; set; }
}
public class WcfConnection : Connection
{
// specificProperties etc.
}
public class RemotingConnection : Connection
{
// specificProperties etc.
}
I am trying to use Ninject to bind these specific types of datasender based on the type of Connection passed from the parameter. 我试图使用Ninject根据从参数传递的Connection类型绑定这些特定类型的数据库。 I have tried the following unsuccessfully: 我尝试了下面的失败:
Bind<IDataSender>()
.To<RemotingDataSender>()
.When(a => a.Parameters.Single(b => b.Name == "connection") as RemotingConnection != null)
I believe this is because '.When' only provides a request and I would need the full context to be able to retrieve the actual parameter value and check its type. 我相信这是因为'。'只提供一个请求,我需要完整的上下文才能检索实际参数值并检查其类型。 I'm at a loss as to what to do, other than using named bindings, actually implementing the factory and putting the logic in there ie 我不知道该做什么,除了使用命名绑定,实际上实现工厂并将逻辑放在那里,即
public IDataSender CreateDataSender(Connection connection)
{
if (connection.GetType() == typeof(WcfConnection))
{
return resolutionRoot.Get<IDataSender>("wcfdatasender", new ConstructorArgument("connection", connection));
}
return resolutionRoot.Get<IDataSender>("remotingdatasender", new ConstructorArgument("connection", connection));
}
After some looking into Ninject source I have found following: 在查看Ninject源代码后,我发现以下内容:
a.Parameters.Single(b => b.Name == "connection")
gives you variable of type IParameter
, not real parameter. a.Parameters.Single(b => b.Name == "connection")
为您提供IParameter
类型的IParameter
,而不是真实参数。
IParameter
has method object GetValue(IContext context, ITarget target)
that requires not null context parameter (target can be null). IParameter
具有方法object GetValue(IContext context, ITarget target)
,它不需要null上下文参数(target可以为null)。
I have not found any way to get IContext from Request (variable a in your sample). 我还没有找到任何方法从Request获取IContext(样本中的变量a)。
Context
class does not have parameterless constructor so we can't create new Context. Context
类没有无参数构造函数,因此我们无法创建新的Context。
To make it work you can create dummy IContext implementation like: 为了使它工作,您可以创建虚拟IContext实现,如:
public class DummyContext : IContext
{
public IKernel Kernel { get; private set; }
public IRequest Request { get; private set; }
public IBinding Binding { get; private set; }
public IPlan Plan { get; set; }
public ICollection<IParameter> Parameters { get; private set; }
public Type[] GenericArguments { get; private set; }
public bool HasInferredGenericArguments { get; private set; }
public IProvider GetProvider() { return null; }
public object GetScope() { return null; }
public object Resolve() { return null; }
}
and than use it 而不是使用它
kernel.Bind<IDataSender>()
.To<RemotingDataSender>()
.When( a => a.Parameters
.Single( b => b.Name == "connection" )
.GetValue( new DummyContext(), a.Target )
as RemotingConnection != null );
It would be nice if someone could post some info about obtaining Context from inside When()
... 如果有人可以发布一些关于从When()
内部获取Context的信息会很好
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