英文:
Problem registering a generic type with DI .net core
问题
I can help you with the translation. Here's the translated portion:
我正在尝试注册用于GraphQL的一些类型，但是对于使用泛型的特定类会出现异常。
该类定义如下：
public class ResponseGraphType<TGraphType, T> : ObjectGraphType<Response<T>> where TGraphType : GraphType
{
public ResponseGraphType()
{
...
并尝试这样注册类：
services.AddScoped(typeof(ResponseGraphType<,>), sp =>
{
Type generic = typeof(ResponseGraphType<,>);
Type constructed = generic.MakeGenericType();
return (GraphType)Activator.CreateInstance(constructed);
});
但是当我启动应用程序时，我得到了这个异常：
>System.ArgumentException: 'Cannot instantiate implementation type 'XXX.XXX.XXX.XXX.ResponseGraphType`2[TGraphType,T]' for service type 'GraphQL.Types.IProvideMetadata'.'
IProvideMetadata是一个由以下类实现的接口：
public class MetadataProvider : IProvideMetadata
...
public interface IProvideMetadata
有关如何注册ResponseGraphType的任何想法吗？
英文:
I'm trying to register some types used for graphql but I get an exception for a specific class that uses generics.
The class is defined like this:
public class ResponseGraphType<TGraphType, T> : ObjectGraphType<Response<T>> where TGraphType : GraphType
{
public ResponseGraphType()
{
...
And tried to register the class like this:
services.AddScoped(typeof(ResponseGraphType<,>), sp =>
{
Type generic = typeof(ResponseGraphType<,>);
Type constructed = generic.MakeGenericType();
return (GraphType)Activator.CreateInstance(constructed);
});
But when I start the application I get this exception:
>System.ArgumentException: 'Cannot instantiate implementation type 'XXX.XXX.XXX.XXX.ResponseGraphType`2[TGraphType,T]' for service type 'GraphQL.Types.IProvideMetadata'.'
The IProvideMetadata is an interface implemented by
public class MetadataProvider : IProvideMetadata
...
public interface IProvideMetadata
Any idea on how to register the ResponseGraphType?
答案1
得分: 1
不可能使用lambda/delegate语法注册开放泛型类型。只有封闭和非泛型服务类型可以使用委托注册。对于开放泛型类型，您需要依赖于自动装配注册语法，也就是您应该执行以下操作：
services.AddScoped(typeof(ResponseGraphType<,>), typeof(ResponseGraphType<,>));
通过这个注册，您指示MS.DI在用户请求该封闭版本的ResponseGraphType<TGraphType, T>时组合并返回适当的封闭版本。
英文:
It's not possible to register open-generic types using the lambda/delegate syntax. Only closed and non-generic service types can be registered using delegate. For open-generic types you need to depend on the Auto-Wiring registration syntax, meaning you should do the following:
services.AddScoped(typeof(ResponseGraphType<,>), typeof(ResponseGraphType<,>));
With this registration you instruct MS.DI to compose and return the appropriate closed version of ResponseGraphType<TGraphType, T> in case the user requests that closed version of ResponseGraphType<TGraphType, T>.
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