[英]Call a method with parameter type Expression<Func<T, object>> using reflection
I need to call below ExpFunction with reflection: 我需要在反射下调用ExpFunction:
class Program
{
static void Main(string[] args)
{
ExpClass<TestClass> obj = new ExpClass<TestClass>();
//without reflection
obj.ExpFunction(f => f.Col);
//with reflection
UsingReflection<TestClass>(obj, typeof(TestClass).GetProperty("Col"));
}
}
public class TestClass
{
public string Col { get; set; }
}
public class ExpClass<T>
{
public string ExpFunction(Expression<Func<T, object>> propertyMap)
{
return "success";
}
}
Here is what I did 这是我所做的
static void UsingReflection<T>(ExpClass<T> obj, PropertyInfo Property)
{
ParameterExpression parameter = Expression.Parameter(typeof(T), "i");
MemberExpression property = Expression.Property(parameter, Property);
var propertyExpression = Expression.Lambda(property, parameter);
var method = typeof(ExpClass<T>).GetMethod("ExpFunction").MakeGenericMethod(typeof(T));
method.Invoke(obj, new object[] { propertyExpression });
}
But During invoke it says: 但是在调用过程中它说:
Object of type 'System.Linq.Expressions.Expression`1[System.Func`2[ExpressionTest.TestClass,System.String]]'
cannot be converted to type 'System.Linq.Expressions.Expression`1[System.Func`2[ExpressionTest.TestClass,System.Object]]'.
It is probably because ExpFunction accepts Expression<Func<T, object>>
. 可能是因为ExpFunction接受
Expression<Func<T, object>>
。 And TestClass.Col
is a string. 而且
TestClass.Col
是一个字符串。
So how can I do it? 那我该怎么办呢?
There are two problems, you're not casting the property to Object
and you call MakeGenericMethod
on a method which is not generic at all. 有两个问题,您没有将属性强制转换为
Object
,而是对根本不是通用的方法调用了MakeGenericMethod
。
static void UsingReflection<T>(ExpClass<T> obj, PropertyInfo Property)
{
ParameterExpression parameter = Expression.Parameter(typeof(T), "i");
MemberExpression property = Expression.Property(parameter, Property);
var castExpression = Expression.TypeAs(property, typeof(object));
var propertyExpression = Expression.Lambda(castExpression, parameter);
var method = typeof(ExpClass<T>).GetMethod("ExpFunction");
method.Invoke(obj, new object[] { propertyExpression });
}
ExpFunction
不是通用的,因此您不应该.MakeGenericMethod(typeof(T))
。
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