C# PropertyInfo用于属性链末端的属性
我有这样的想法:C# PropertyInfo用于属性链末端的属性,c#,reflection,C#,Reflection,我有这样的想法: class OriginalClass { public Type2 object2 { get; set; } } class Type2 { public Type3 object3 { get; set; } } class Type3 { public Type4 object4 { get; set; } } var obj = new OriginalClass(); var object4 = obj.object2.object3.
class OriginalClass
{
public Type2 object2 { get; set; }
}
class Type2
{
public Type3 object3 { get; set; }
}
class Type3
{
public Type4 object4 { get; set; }
}
var obj = new OriginalClass();
var object4 = obj.object2.object3.object4;
我还有一个字符串值:
object2.object3.object4
这是通过object2和object3从类型T到object4的路径,这两个属性都返回对象。object4是object3上的属性
如何为最后一个property object4动态创建PropertyInfo对象?您可以实现如下扩展方法:
public static class TypeExtensions
{
/// <summary>Looks for a property using an object path where each
/// property to match is accessed using dot syntax</summary>
public static PropertyInfo GetPropertyByPath(this Type someType, string objectPath, BindingFlags bindingFlags = BindingFlags.Instance | BindingFlags.Public)
{
string[] objectPathParts = objectPath.Split('.');
// #1 property in the object path should be obtained from T
PropertyInfo currentProperty = someType.GetProperty(objectPathParts[0], bindingFlags);
for (int propertyIndex = 1; propertyIndex < objectPathParts.Length; propertyIndex++)
{
// While all other association properties should be obtained
// accessing PropertyInfo.PropertyType
currentProperty = currentProperty.PropertyType.GetProperty(objectPathParts[propertyIndex], bindingFlags);
if (currentProperty == null)
throw new ArgumentException("Some property in the object path doesn't exist", "objectPath");
}
return currentProperty;
}
}
方法2:使用表达式树。更好更简单!
您还可以使用较少的反射来解决此问题:
public static class ReflectionHelper
{
public static PropertyInfo GetPropertyByPath<T>(Expression<Func<T, object>> pathExpr)
{
// It must be a member access expression like "x.y.z"
MemberExpression propertyAccessExpr = pathExpr.Body as MemberExpression;
// if it's not a member access expression, return null
if(propertyAccessExpr == null)
return null;
return propertyAccessExpr.Member as PropertyInfo;
}
}
然后获取路径中的最后一个属性信息,如下所示:
PropertyInfo object4Info = typeof(OriginalClass).GetPropertyByPath("object2.object3.object4");
PropertyInfo object4Info = ReflectionHelper
.GetPropertyByPath<OriginalClass>(c => c.object2.object3.object4);
使用下面的代码,您可以执行以下操作:
PropertyInfo pi = GetPropertyInfoFromPath(obj.GetType(), "object2.object3.object4");
我仍然需要把这篇文章作为一块金块来发表,但这里是我的反射库的摘录
public static PropertyInfo GetPropertyInfoFromPath<T>(string path)
{
var type = typeof(T);
return GetPropertyInfoFromPath(type, path);
}
public static PropertyInfo GetPropertyInfoFromPath(Type type, string path)
{
var parts = path.Split('.');
var count = parts.Count();
if (count == 0)
throw new InvalidOperationException("Not a valid path");
if (count == 1)
return GetPropertyInformation(type, parts.First());
else
{
var t = GetPropertyInformation(type, parts[0]).PropertyType;
return GetPropertyInfoFromPath(t, string.Join(".", parts.Skip(1)));
}
}
你的问题相当含糊。有趣的是object2的类型。你到底想解决什么问题?这看起来像一个.@ WaHalee让我们把它看作Obj.Objt2.Objut3.Objt4,其中OBJ是Type T.的一个实例。我想用RealthIdId编辑你的问题来包含最后一个属性Objist4的PrimeType信息对象,其中包括一些代码,我认为这些代码涵盖了你要问的内容。如果这不是你想要的,请随意回复,但我认为人们会尽力帮助你解决你的问题。我还编辑了你的标题“嵌套对象”表示嵌套类,即定义在另一个类中的类。
public static Type GetPropertyType<T>(Expression<Func<T, object>> expression)
{
var info = GetPropertyInformation(expression) as PropertyInfo;
return info.PropertyType;
}
public static MemberInfo GetPropertyInformation<T>(Expression<Func<T, object>> propertyExpression)
{
return PropertyInformation(propertyExpression.Body);
}
public static PropertyInfo PropertyInformation(Expression propertyExpression)
{
MemberExpression memberExpr = propertyExpression as MemberExpression;
if (memberExpr == null)
{
UnaryExpression unaryExpr = propertyExpression as UnaryExpression;
if (unaryExpr != null && unaryExpr.NodeType == ExpressionType.Convert)
{
memberExpr = unaryExpr.Operand as MemberExpression;
}
}
if (memberExpr != null)
{
var propertyMember = memberExpr.Member as PropertyInfo;
if (propertyMember != null)
return propertyMember;
}
return null;
}
[Fact]
public void GetPropertyInfo_FromInstanceNestedPropertyUsingPathString_ReturnsPropertyInfo()
{
var deepType = Helper.GetPropertyInfoFromPath<TestModel>("Nested.Deep");
var deepDeclaringType = Helper.GetPropertyInfoFromPath<TestModel>("Nested");
Assert.Equal(typeof(string), deepType.PropertyType);
Assert.Equal(typeof(NestedModel), deepDeclaringType.PropertyType);
}
public class TestModel : Base
{
public int Id { get; set; }
[PickMe]
public string MyString { get; set; }
public NestedModel Nested { get; set; }
public DateTime ClosedAt { get; set; }
}
public class NestedModel
{
public string Deep { get; set; }
}