使用 Autofac 注册部分封闭的泛型类型 [英] Register partically closed generic type with Autofac

问题描述

我有 UnitofWork 类，它实现了 IUnitOfWork.我尝试向 Autofac 注册:

I have UnitofWork class and it implement IUnitOfWork. I try to register that with Autofac:

var builder = new ContainerBuilder();
builder
    .RegisterGeneric(typeof(UnitOfWork<Repository<>,>))
    .As(typeof(IUnitOfWork))
    .InstancePerDependency();

实现是:

public class UnitOfWork<T, O> : IUnitOfWork
    where T : Repository<O>
    where O : BaseEntity
{
}

public interface IUnitOfWork : IDisposable
{
    void SaveChanges();
}

给出错误预期类型"

但是这个在另一个项目上工作:

but this one work on another project:

public class Repository<T> : GenericRepository<T> 
    where T : BaseEntity
{
    public Repository(IDbContext context) : base(context) { }   
}

public abstract class GenericRepository<T> 
    : IRepository<T>, IQueryable<T> where T : BaseEntity
{
}

builder
    .RegisterGeneric(typeof(Repository<>))
    .As(typeof(IRepository<>))
    .InstancePerHttpRequest();

推荐答案

你不能有部分打开的类(例如，使用 UnitOfWork,> 你在 typeof 中指定了 T 但没有指定 O) ，试试:

You cannot have partially opened classes (e.g. with UnitOfWork<Repository<>,> you have specified T but not O) inside a typeof, try it with:

var builder = new ContainerBuilder();
builder
    .RegisterGeneric(typeof(UnitOfWork<,>))
    .As(typeof(IUnitOfWork))
    .InstancePerDependency();

where T : Repository 通用约束将负责第一个参数应该是 Repository<>

The where T : Repository<O> generic constraint will take care of that the first argument should be an Repository<>

但是它不适用于RegisterGeneric，因为它需要一个通用接口，所以需要创建一个IUnitOfWork...

But it won't work with RegisterGeneric because it requires a generic interface so need to create a IUnitOfWork<T,O>…

但是你的模型很奇怪.为什么你的 UnitOfWork 需要一个 Repository<> 类型参数?

But your model is very strange. Why does your UnitOfWork need a Repository<> type argument?

您可以在 UnitOfWork 构造函数中获得一个 Repository<>，而不是将其作为类型参数:

Instead of having it as a type argument you can get an Repository<> in your UnitOfWork<E> constructor:

public class UnitOfWork<E> : IUnitOfWork<E> where E : BaseEntity
{
    private readonly Repository<E> repository;

    public UnitOfWork(Repository<E> repository)
    {
        this.repository = repository;
    }

    //.. other methods

}

其中 IUnitOfWork

public interface IUnitOfWork<E> : IDisposable where E : BaseEntity
{
    void SaveChanges();
}

和 Autofac 注册:

And the Autofac registration:

var builder = new ContainerBuilder();
builder
    .RegisterGeneric(typeof(Repository<>)).AsSelf();
builder
    .RegisterGeneric(typeof(UnitOfWork<>))
    .As(typeof(IUnitOfWork<>))
    .InstancePerDependency();
var container = builder.Build();

// sample usage
var u = container.Resolve<IUnitOfWork<MyEntity>>();

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