C# 用于2+的Ninject上下文绑定;同一构造函数参数具有不同名称的依赖类
在两个类具有相同的底层接口依赖关系,但每个类的参数命名不同的情况下,很难理解如何管理上下文绑定。下面的伪代码演示了我的情况:C# 用于2+的Ninject上下文绑定;同一构造函数参数具有不同名称的依赖类,c#,dependency-injection,ninject,contextual-binding,C#,Dependency Injection,Ninject,Contextual Binding,在两个类具有相同的底层接口依赖关系,但每个类的参数命名不同的情况下,很难理解如何管理上下文绑定。下面的伪代码演示了我的情况: interface IThing { } public class Thing1 : IThing { public Thing1(string fileCode) { } } public class Thing2 : IThing { public Thing2(string fileCode) { } } interface IThi
interface IThing { }
public class Thing1 : IThing { public Thing1(string fileCode) { } }
public class Thing2 : IThing { public Thing2(string fileCode) { } }
interface IThingFactory { IThing CreateThing(string fileCode); }
interface IDependentThing { }
public class A : IDependentThing { public A(string fileCode, IThingFactory thingFactory) { } }
public class B : IDependentThing { public B(string fileCd, IThingFactory thingFactory) { } } //How to handle binding for this dependent?
interface IDependentThingFactory { IDependentThing CreateDependentThing(string fileCode); }
//...
public override void Load()
{
Bind<IThing>().ToMethod(ctx =>
{
var fileCode = ctx.Parameters.First(p => p.Name == "fileCode").GetValue(ctx, null) as string;
IThing thing = null;
if (fileCode == "FileType1")
{
Bind<Thing1>().ToSelf().WithConstructorArgument("fileCode", fileCode);
thing = Kernel.Get<Thing1>();
}
else if (fileCode == "FileType2")
{
Bind<Thing2>().ToSelf().WithConstructorArgument("fileCode", fileCode);
thing = Kernel.Get<Thing2>();
}
return thing;
});
Bind<IThingFactory>().ToFactory();
Bind<IDependentThingFactory>().ToFactory();
}
//Later...
using (TextReader tr = new StreamReader(path))
{
string firstLine = tr.ReadLine();
if (firstLine.Substring(838, 1) == ".")
{
fileCode = "FileType1";
}
else if (firstLine.Substring(883, 1) == ".")
{
fileCode = "FileType2";
}
//won't work for creating B
Kernel.Get<IDependentThing>(new ConstructorArgument("fileCode", fileCode));
//or maybe...
//seems to eliminate my problem by allowing me to handle variations
//in parameter names from within A and B's ctors, but looks like it
//requires injecting factories along the chain (see A & B ctor arguments).
dependentThingFactory.CreateDependentThing(fileCode)
};
interface-IThing{}
公共类Thing1:IThing{public Thing1(字符串文件代码){}
公共类Thing2:IThing{public Thing2(字符串文件代码){}
接口i ThingFactory{i Thing CreateThing(字符串文件代码);}
接口IDependentThing{}
公共类A:IDependentThing{public A(字符串文件代码,i thingFactory thingFactory){}
public类B:IDependentThing{public B(string fileCd,IThingFactory thingFactory){}//如何处理此依赖项的绑定?
接口IDependentThingFactory{IDependentThing CreateDependentThing(字符串文件代码);}
//...
公共覆盖无效负载()
{
Bind().ToMethod(ctx=>
{
var fileCode=ctx.Parameters.First(p=>p.Name==“fileCode”).GetValue(ctx,null)作为字符串;
i thing thing=null;
如果(文件代码==“文件类型1”)
{
Bind().ToSelf().WithConstructorArgument(“fileCode”,fileCode);
thing=Kernel.Get();
}
else if(fileCode==“FileType2”)
{
Bind().ToSelf().WithConstructorArgument(“fileCode”,fileCode);
thing=Kernel.Get();
}
归还物;
});
Bind().ToFactory();
Bind().ToFactory();
}
//后来。。。
使用(TextReader tr=新的StreamReader(路径))
{
字符串firstLine=tr.ReadLine();
if(第一行子字符串(838,1)==”)
{
fileCode=“FileType1”;
}
else if(第一行子字符串(883,1)=“)
{
fileCode=“FileType2”;
}
//不适用于创建B
Get(新的构造函数参数(“fileCode”,fileCode));
//或者也许。。。
//似乎通过允许我处理变化来消除我的问题
//在A和B的系数内的参数名称中,但看起来像
//需要沿着供应链注入工厂(参见A&B)。
dependentThingFactory.CreateDependentThing(文件代码)
};
fileCode
是根据对本地文件的一些分析计算出来的。一旦确定了文件类型,我希望Ninject返回处理该文件的适当对象
既然我定义的现有绑定需要具有不同名称的构造函数参数,那么如何处理B
的绑定?一般来说,有没有更好的方法
我想我可以用p.Name==“fileCode”| | p.Name==“fileCd”
,但我无法摆脱我做错了什么(感觉凌乱)的感觉。此外,我对按名称提取参数并不感到兴奋,我还考虑过创建一个自定义类型,与字符串参数相比,它可以为Ninject提供更具体的匹配对象。从我的立场来看,我要么只是管理多个参数名的情况,要么切换到自定义类型作为我的参数而不是字符串。使参数注入更安全地重构,并使它们可用于整个解析上下文
您可以使用“类型匹配”或“类型化”参数,而不是“命名参数”。工厂IInstanceProvider
可以换成另一个这样做的工厂:
kernel.Bind<IThingFactory>()
.ToFactory(() => new TypeMatchingArgumentInheritanceInstanceProvider());
(可能您想用enum
?)替换它)
由于您的需求更为复杂,我们将不得不稍微改变一下。
我们将创建自己的IConstructorArgument
,以便在上下文绑定时能够轻松地为匹配它,并基于类型匹配注入它的值(如上所述):
现在,让我创建一些示例代码,以便稍后验证它是否有效:
public interface IThing
{
FileCode FileCode { get; }
}
public abstract class Thing : IThing
{
protected Thing(FileCode fileCode)
{
FileCode = fileCode;
}
public FileCode FileCode { get; private set; }
}
public class ThingFoo : Thing
{
public ThingFoo(FileCode fileCode) : base(fileCode) { }
}
public class ThingBar : Thing
{
public ThingBar(FileCode fileCode) : base(fileCode) { }
}
public interface IOtherThing
{
FileCode FileCode { get; }
}
public abstract class OtherThing : IOtherThing
{
protected OtherThing(FileCode fileCode)
{
FileCode = fileCode;
}
public FileCode FileCode { get; private set; }
}
public class OtherThingFoo : OtherThing
{
public OtherThingFoo(FileCode fileCode) : base(fileCode) { }
}
public class OtherThingBar : OtherThing
{
public OtherThingBar(FileCode fileCode) : base(fileCode) { }
}
public class OtherThingWrapper
{
public OtherThingWrapper(IOtherThing otherThing)
{
OtherThing = otherThing;
}
public IOtherThing OtherThing { get; private set; }
}
public class FileProcessor
{
public FileProcessor(IThing thing, OtherThingWrapper otherThingWrapper)
{
Thing = thing;
OtherThingWrapper = otherThingWrapper;
}
public IThing Thing { get; private set; }
public OtherThingWrapper OtherThingWrapper { get; private set; }
}
少了什么?工厂。我们可以将ToFactory
绑定到定制IInstanceProvider
上,但除非我们要用FileCodeParameter
s创建大量工厂,否则我认为这没有意义,所以让我们保持简单:
public interface IFileProcessorFactory
{
FileProcessor Create(FileCode fileCode);
}
internal class FileProcessorFactory : IFileProcessorFactory
{
private readonly IResolutionRoot resolutionRoot;
public FileProcessorFactory(IResolutionRoot resolutionRoot)
{
this.resolutionRoot = resolutionRoot;
}
public FileProcessor Create(FileCode fileCode)
{
return this.resolutionRoot.Get<FileProcessor>(new FileCodeParameter(fileCode));
}
}
从何处获取连接字符串的值?这是“静态”吗。。。或者在请求的上下文中,或者..?我只是以connectionString为例。然而,我的实际代码使用的是字符串参数。我想要的可能是一种更干净的获取字符串参数的方法,但我不确定如何获取(我的预期可能不符合)。对我来说,为A的“connectionString”ctor参数设置绑定,然后还要考虑B的名为“connStr”的ctor参数似乎有问题。显然,如果我在图中添加一个C类,它可能会有“cStr”。因此,我必须不断更改代码,以考虑同一概念事物的参数命名的变化。此外,我认为我可能错误地设置了此设置,因为我对需要传递给链中多个依赖项的参数的工作方式存在误解。看起来,如果我将A和B的因子更改为接受IThingFactory而不是IThing,那么A和B的因子中参数命名的变化可以在那里的因子中处理,而不是在绑定代码中处理。无论如何,如果我错了,请纠正我,或者建议一个更好的方法,我仍然在学习Ninject的诀窍。但是字符串参数(值)是从哪里来的呢?它不是凭空产生的,是吗?;-)您的问题涉及到几个技术“问题”:1)传递参数,2)进一步传递参数,3)根据上下文信息选择类型。现在,根据参数的来源以及该信息的有效期,我们可以完全改变如何执行3)的方法,可能会影响1)和2)或使2)
public interface IThing
{
FileCode FileCode { get; }
}
public abstract class Thing : IThing
{
protected Thing(FileCode fileCode)
{
FileCode = fileCode;
}
public FileCode FileCode { get; private set; }
}
public class ThingFoo : Thing
{
public ThingFoo(FileCode fileCode) : base(fileCode) { }
}
public class ThingBar : Thing
{
public ThingBar(FileCode fileCode) : base(fileCode) { }
}
public interface IOtherThing
{
FileCode FileCode { get; }
}
public abstract class OtherThing : IOtherThing
{
protected OtherThing(FileCode fileCode)
{
FileCode = fileCode;
}
public FileCode FileCode { get; private set; }
}
public class OtherThingFoo : OtherThing
{
public OtherThingFoo(FileCode fileCode) : base(fileCode) { }
}
public class OtherThingBar : OtherThing
{
public OtherThingBar(FileCode fileCode) : base(fileCode) { }
}
public class OtherThingWrapper
{
public OtherThingWrapper(IOtherThing otherThing)
{
OtherThing = otherThing;
}
public IOtherThing OtherThing { get; private set; }
}
public class FileProcessor
{
public FileProcessor(IThing thing, OtherThingWrapper otherThingWrapper)
{
Thing = thing;
OtherThingWrapper = otherThingWrapper;
}
public IThing Thing { get; private set; }
public OtherThingWrapper OtherThingWrapper { get; private set; }
}
public interface IFileProcessorFactory
{
FileProcessor Create(FileCode fileCode);
}
internal class FileProcessorFactory : IFileProcessorFactory
{
private readonly IResolutionRoot resolutionRoot;
public FileProcessorFactory(IResolutionRoot resolutionRoot)
{
this.resolutionRoot = resolutionRoot;
}
public FileProcessor Create(FileCode fileCode)
{
return this.resolutionRoot.Get<FileProcessor>(new FileCodeParameter(fileCode));
}
}
public class Test
{
[Fact]
public void FactMethodName()
{
var fooFileCode = new FileCode("foo");
var barFileCode = new FileCode("bar");
var kernel = new StandardKernel();
kernel
.Bind<IFileProcessorFactory>()
.To<FileProcessorFactory>();
kernel
.Bind<IThing>()
.To<ThingFoo>()
.WhenFileCode(fooFileCode);
kernel
.Bind<IThing>()
.To<ThingBar>()
.WhenFileCode(barFileCode);
kernel
.Bind<IOtherThing>()
.To<OtherThingFoo>()
.WhenFileCode(fooFileCode);
kernel
.Bind<IOtherThing>()
.To<OtherThingBar>()
.WhenFileCode(barFileCode);
var fileProcessor = kernel.Get<IFileProcessorFactory>().Create(barFileCode);
fileProcessor.Thing.Should().BeOfType<ThingBar>();
fileProcessor.Thing.FileCode.Should().Be(barFileCode);
fileProcessor.OtherThingWrapper.OtherThing.Should().BeOfType<OtherThingBar>();
fileProcessor.OtherThingWrapper.OtherThing.FileCode.Should().Be(barFileCode);
}
}
public static class BindingExtensionsForFileCodes
{
public static IBindingInNamedWithOrOnSyntax<T> WhenFileCode<T>(
this IBindingWhenSyntax<T> syntax,
FileCode fileCode)
{
return syntax.When(req => req
.Parameters
.OfType<FileCodeParameter>()
.Single()
.FileCode.Value == fileCode.Value);
}
}
using FluentAssertions;
using Ninject;
using Ninject.Activation;
using Ninject.Parameters;
using Ninject.Planning.Targets;
using Ninject.Syntax;
using System.Linq;
using Xunit;
namespace NinjectTest.ParameterContextual
{
public class FileCode
{
public FileCode(string value)
{
Value = value;
}
public string Value { get; private set; }
}
public interface IThing
{
FileCode FileCode { get; }
}
public abstract class Thing : IThing
{
protected Thing(FileCode fileCode)
{
FileCode = fileCode;
}
public FileCode FileCode { get; private set; }
}
public class ThingFoo : Thing
{
public ThingFoo(FileCode fileCode) : base(fileCode) { }
}
public class ThingBar : Thing
{
public ThingBar(FileCode fileCode) : base(fileCode) { }
}
public interface IOtherThing
{
FileCode FileCode { get; }
}
public abstract class OtherThing : IOtherThing
{
protected OtherThing(FileCode fileCode)
{
FileCode = fileCode;
}
public FileCode FileCode { get; private set; }
}
public class OtherThingFoo : OtherThing
{
public OtherThingFoo(FileCode fileCode) : base(fileCode) { }
}
public class OtherThingBar : OtherThing
{
public OtherThingBar(FileCode fileCode) : base(fileCode) { }
}
public class OtherThingWrapper
{
public OtherThingWrapper(IOtherThing otherThing)
{
OtherThing = otherThing;
}
public IOtherThing OtherThing { get; private set; }
}
public class FileProcessor
{
public FileProcessor(IThing thing, OtherThingWrapper otherThingWrapper)
{
Thing = thing;
OtherThingWrapper = otherThingWrapper;
}
public IThing Thing { get; private set; }
public OtherThingWrapper OtherThingWrapper { get; private set; }
}
public interface IFileProcessorFactory
{
FileProcessor Create(FileCode fileCode);
}
internal class FileProcessorFactory : IFileProcessorFactory
{
private readonly IResolutionRoot resolutionRoot;
public FileProcessorFactory(IResolutionRoot resolutionRoot)
{
this.resolutionRoot = resolutionRoot;
}
public FileProcessor Create(FileCode fileCode)
{
return this.resolutionRoot.Get<FileProcessor>(new FileCodeParameter(fileCode));
}
}
public class Test
{
[Fact]
public void FactMethodName()
{
var fooFileCode = new FileCode("foo");
var barFileCode = new FileCode("bar");
var kernel = new StandardKernel();
kernel
.Bind<IFileProcessorFactory>()
.To<FileProcessorFactory>();
kernel
.Bind<IThing>()
.To<ThingFoo>()
.WhenFileCode(fooFileCode);
kernel
.Bind<IThing>()
.To<ThingBar>()
.WhenFileCode(barFileCode);
kernel
.Bind<IOtherThing>()
.To<OtherThingFoo>()
.WhenFileCode(fooFileCode);
kernel
.Bind<IOtherThing>()
.To<OtherThingBar>()
.WhenFileCode(barFileCode);
var fileProcessor = kernel.Get<IFileProcessorFactory>().Create(barFileCode);
fileProcessor.Thing.Should().BeOfType<ThingBar>();
fileProcessor.Thing.FileCode.Should().Be(barFileCode);
fileProcessor.OtherThingWrapper.OtherThing.Should().BeOfType<OtherThingBar>();
fileProcessor.OtherThingWrapper.OtherThing.FileCode.Should().Be(barFileCode);
}
}
internal class FileCodeParameter : IConstructorArgument
{
private readonly FileCode fileCode;
public FileCodeParameter(FileCode fileCode)
{
this.fileCode = fileCode;
}
public string Name { get { return "File Code Parameter"; } }
public bool ShouldInherit { get { return true; } }
public FileCode FileCode { get { return this.fileCode; } }
public bool Equals(IParameter other)
{
var otherFileCodeParameter = other as FileCodeParameter;
if (otherFileCodeParameter == null)
{
return false;
}
return otherFileCodeParameter.fileCode == this.fileCode;
}
public object GetValue(IContext context, ITarget target)
{
return this.fileCode;
}
public bool AppliesToTarget(IContext context, ITarget target)
{
return target.Type == typeof(FileCode);
}
}
public static class BindingExtensionsForFileCodes
{
public static IBindingInNamedWithOrOnSyntax<T> WhenFileCode<T>(
this IBindingWhenSyntax<T> syntax,
FileCode fileCode)
{
return syntax.When(req => req
.Parameters
.OfType<FileCodeParameter>()
.Single()
.FileCode.Value == fileCode.Value);
}
}
}