我怎么知道一个属性是否是一个通用集合

Question

我需要知道类中属性的类型是否是使用PropertyInfo类的泛型集合（List，ObservableCollection）。

foreach (PropertyInfo p in (o.GetType()).GetProperties()) 
{ 
    if(p is Collection<T> ?????) 

} 

Answer 1

GetGenericTypeDefinition和typeof(Collection<>)将做的工作：

if(p.PropertyType.IsGenericType && typeof(Collection<>).IsAssignableFrom(p.PropertyType.GetGenericTypeDefinition()) 

Answer 2

Type tColl = typeof(ICollection<>); 
foreach (PropertyInfo p in (o.GetType()).GetProperties()) { 
    Type t = p.PropertyType; 
    if (t.IsGenericType && tColl.IsAssignableFrom(t.GetGenericTypeDefinition()) || 
     t.GetInterfaces().Any(x => x.IsGenericType && x.GetGenericTypeDefinition() == tColl)) { 
     Console.WriteLine(p.Name + " IS an ICollection<>"); 
    } else { 
     Console.WriteLine(p.Name + " is NOT an ICollection<>"); 
    } 
} 

你需要测试t.IsGenericType和x.IsGenericType，否则，如果该类型不是通用GetGenericTypeDefinition()会抛出异常。

如果该物业被宣布为ICollection<T>那么tColl.IsAssignableFrom(t.GetGenericTypeDefinition())将返回true。

如果属性声明为它实现ICollection<T>一个类型，然后 t.GetInterfaces().Any(x => x.IsGenericType && x.GetGenericTypeDefinition() == tColl)将返回true。

请注意，例如tColl.IsAssignableFrom(t.GetGenericTypeDefinition())返回false为List<int>。

---

我已经测试所有这些组合为MyT o = new MyT();

private interface IMyCollInterface1 : ICollection<int> { } 
private interface IMyCollInterface2<T> : ICollection<T> { } 
private class MyCollType1 : IMyCollInterface1 { ... } 
private class MyCollType2 : IMyCollInterface2<int> { ... } 
private class MyCollType3<T> : IMyCollInterface2<T> { ... } 

private class MyT 
{ 
    public ICollection<int> IntCollection { get; set; } 
    public List<int> IntList { get; set; } 
    public IMyCollInterface1 iColl1 { get; set; } 
    public IMyCollInterface2<int> iColl2 { get; set; } 
    public MyCollType1 Coll1 { get; set; } 
    public MyCollType2 Coll2 { get; set; } 
    public MyCollType3<int> Coll3 { get; set; } 
    public string StringProp { get; set; } 
} 

输出：

IntCollection IS an ICollection<> 
IntList IS an ICollection<> 
iColl1 IS an ICollection<> 
iColl2 IS an ICollection<> 
Coll1 IS an ICollection<> 
Coll2 IS an ICollection<> 
Coll3 IS an ICollection<> 
StringProp is NOT an ICollection<>