IsGenericType和IsGenericTypeDefinition之间的区别

问题描述

Type.IsGenericType和Type.IsGenericTypeDefinition有什么区别?有趣的是，用于IsGenericTypeDefinition的MSDN链接已断开.

What is the difference between Type.IsGenericType and Type.IsGenericTypeDefinition ? Interestingly enough, MSDN's link for IsGenericTypeDefinition is broken.

在尝试检索给定DbContext中定义的所有DbSet之后，我得到了以下结果，这是我试图理解的行为:通过IsGenericType筛选属性返回所需的结果，而使用IsGenericTypeDefinition则不会(不会不返回任何内容.)

After playing a bit with trying to retrieve all the DbSets defined in a given DbContext, I was lead to the following, which behavior I am trying to understand: filtering properties via IsGenericType returns the desired results, while with IsGenericTypeDefinition not (does not return any).

有趣的是，从这篇帖子中，我的印象是作者确实得到了他的DbSet使用IsGenericTypeDefinition，而我没有.

It's interesting that from this post I have the impression that the author did get his DbSets using IsGenericTypeDefinition, while I did not.

以下示例说明了该讨论:

Follows a sample that illustrates the discussion:

private static void Main(string[] args)
{
    A a = new A();
    int propertyCount = a.GetType().GetProperties().Where(p => p.PropertyType.IsGenericType).Count();
    int propertyCount2 = a.GetType().GetProperties().Where(p => p.PropertyType.IsGenericTypeDefinition).Count();

    Console.WriteLine("count1: {0}  count2: {1}", propertyCount, propertyCount2);
}

// Output: count1: 1  count2: 0

public class A
{
    public string aaa { get; set; }
    public List<int> myList { get; set; }
}

推荐答案

IsGenericType告诉您System.Type的此实例表示具有指定的所有类型参数的泛型类型.例如，List<int>是通用类型.

IsGenericType tells you that this instance of System.Type represents a generic type with all its type parameters specified. For example, List<int> is a generic type.

IsGenericTypeDefinition告诉您System.Type的此实例表示一个定义，可以通过为其类型参数提供类型参数来构造泛型类型.例如，List<>是通用类型定义.

IsGenericTypeDefinition, on the other hand, tells you that this instance of System.Type represents a definition from which generic types can be constructed by supplying type arguments for its type parameters. For example, List<> is a generic type definition.

您可以通过调用GetGenericTypeDefinition来获得通用类型的通用类型定义:

You can get a generic type definition of a generic type by calling GetGenericTypeDefinition:

var listInt = typeof(List<int>);
var typeDef = listInt.GetGenericTypeDefinition(); // gives typeof(List<>)

您可以通过为通用类型定义提供MakeGenericType的类型参数来从通用类型定义中创建通用类型:

You can make a generic type from a generic type definition by providing it with type arguments to MakeGenericType:

var listDef = typeof(List<>);
var listStr = listDef.MakeGenericType(typeof(string));

这篇关于IsGenericType和IsGenericTypeDefinition之间的区别的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！