How to dynamically set a property of a class without using reflection (with dynamic) in C# 4 when property name is coming from another source - reflection

Question

I'm building/updating an EntityFramework EntityObject on runtime. I want to set the properties of the entity class, property names and values are coming from another source.
So I'm doing this;
public static EntityCollection<T> UpdateLocaleEntity<T>(EntityCollection<T> entityCollectionToUpdate, params ILocaleControl[] values) where T : EntityObject
{
foreach (var x in entityCollectionToUpdate)
{
Type t = typeof(T);
dynamic localeEntity = x;
string cultureCode = localeEntity.CultureCode;
for (int j = 0; j < values.Length; j++)
{
var value = values[j].GetLocaleValue(cultureCode);
t.GetProperty(values[j].EntityPropertyName).SetValue(localeEntity, value, null);
}
}
return entityCollectionToUpdate;
}
So, how can I get rid of "t.GetProperty(values[j].EntityPropertyName).SetValue(localeEntity, value, null);" part, is there a dynamic way of doing this?
Something like;
dynamicCastedLocaleEntity.GetProperty(values[j].EntityPropertyName) = value;
Thanks.

Answer 1

Long answer coming up.
Reflection is great in many situations, horrible in some but in almost all cases it's slow.
There are at least 4 different ways to set a property in .NET without having to use reflection.
I thought I demonstrate one of them: Using compiled expression trees. Note that the expression building is rather expensive too so that's why it's very important to cache the delegate one builds with it in a dictionary (for instance):
Expression Trees was introduced in .NET35 and is used for many things. Here I use them to build a property setter expression and then compile it into a delegate.
The example demonstrates different timing for the different cases but here are my numbers:
Control case (hard coded): 0.02s
Reflection: 1.78s
Expression Tree: 0.06s
using System;
using System.Linq.Expressions;
namespace DifferentPropertSetterStrategies
{
class TestClass
{
public string XY
{
get;
set;
}
}
class DelegateFactory
{
public static Action<object, object> GenerateSetPropertyActionForControl(
)
{
return (inst, val) => ((TestClass) inst).XY = (string) val;
}
public static Action<object, object> GenerateSetPropertyActionWithReflection(
Type type,
string property
)
{
var propertyInfo = type.GetProperty(property);
return (inst, val) => propertyInfo.SetValue (inst, val, null);
}
public static Action<object,object> GenerateSetPropertyActionWithLinqExpression (
Type type,
string property
)
{
var propertyInfo = type.GetProperty(property);
var propertyType = propertyInfo.PropertyType;
var instanceParameter = Expression.Parameter(typeof(object), "instance");
var valueParameter = Expression.Parameter(typeof(object), "value");
var lambda = Expression.Lambda<Action<object, object>> (
Expression.Assign (
Expression.Property (Expression.Convert (instanceParameter, type), propertyInfo),
Expression.Convert(valueParameter, propertyType)),
instanceParameter,
valueParameter
);
return lambda.Compile();
}
}
static class Program
{
static void Time (
string tag,
object instance,
object value,
Action<object, object > action
)
{
// Cold run
action(instance, value);
var then = DateTime.Now;
const int Count = 2000000;
for (var iter = 0; iter < Count; ++iter)
{
action (instance, value);
}
var diff = DateTime.Now - then;
Console.WriteLine ("{0} {1} times - {2:0.00}s", tag, Count, diff.TotalSeconds);
}
static void Main(string[] args)
{
var instance = new TestClass ();
var instanceType = instance.GetType ();
const string TestProperty = "XY";
const string TestValue = "Test";
// Control case which just uses a hard coded delegate
Time(
"Control",
instance,
TestValue,
DelegateFactory.GenerateSetPropertyActionForControl ()
);
Time(
"Reflection",
instance,
TestValue,
DelegateFactory.GenerateSetPropertyActionWithReflection (instanceType, TestProperty)
);
Time(
"Expression Trees",
instance,
TestValue,
DelegateFactory.GenerateSetPropertyActionWithLinqExpression(instanceType, TestProperty)
);
Console.ReadKey();
}
}
}

Answer 2

For FuleSnabel's answer, you can speed it up a lot (sometimes twice as fast in my tests). In some tests, it was just as fast as the Control solution:
public static Action<Object,Object> GenerateSetPropertyActionWithLinqExpression2(Type type, String property) {
PropertyInfo pi = type.GetProperty(property,BindingFlags.Instance|BindingFlags.Public);
MethodInfo mi = pi.GetSetMethod();
Type propertyType = pi.PropertyType;
var instance = Expression.Parameter(typeof(Object), "instance");
var value = Expression.Parameter(typeof(Object), "value");
var instance2 = Expression.Convert(instance, type);
var value2 = Expression.Convert(value, pi.PropertyType);
var callExpr = Expression.Call(instance2, mi, value2);
return Expression.Lambda<Action<Object,Object>>(callExpr, instance, value).Compile();
}

Answer 3

possibly not with EntityObject, but if you've had an ExpandoObject than you can do
dynamic entity = new ExpandoObject();
(entity as IDictionary<String, Object>)[values[j].EntityPropertyName] = value

Answer 4

The open source framework ImpromptuInterface has methods to invoke based on a string using the DLR rather than reflection and runs faster than reflection too.
Impromptu.InvokeSet(localeEntity, values[j].EntityPropertyName,value);

Answer 5

I'm afraid not. Any use of a dynamic object is baked-in at compile time. Any call which could vary at run-time has to be done using reflection.