.net - property - bindingflags

¿Es posible establecer propiedad privada a través de la reflexión?

Question

¿Puedo establecer una propiedad privada a través de la reflexión?

public abstract class Entity
{
private int _id;
private DateTime? _createdOn;
public virtual T Id
{
get { return _id; }
private set { ChangePropertyAndNotify(ref _id, value, x => Id); }
}
public virtual DateTime? CreatedOn
{
get { return _createdOn; }
private set { ChangePropertyAndNotify(ref _createdOn, value, x => CreatedOn); }
}
}

He intentado lo siguiente y no funciona, donde t representa un tipo de Entity :

var t = typeof(Entity);
var mi = t.GetMethod("set_CreatedOn", BindingFlags.Instance | BindingFlags.NonPublic);

Creo que puedo hacer esto pero no puedo resolverlo.

Answer 1

Ninguno de estos funcionó para mí, y el nombre de mi propiedad era único, así que acabo de usar esto:

public static void SetPrivatePropertyValue<T>(T obj, string propertyName, object newValue)
{
// add a check here that the object obj and propertyName string are not null
foreach (FieldInfo fi in obj.GetType().GetFields(BindingFlags.Instance | BindingFlags.NonPublic))
{
if (fi.Name.ToLower().Contains(propertyName.ToLower()))
{
fi.SetValue(obj, newValue);
break;
}
}
}

Answer 2

Puede acceder a setter privado desde el tipo derivado mediante código

public static void SetProperty(object instance, string propertyName, object newValue)
{
Type type = instance.GetType();
PropertyInfo prop = type.BaseType.GetProperty(propertyName);
prop.SetValue(instance, newValue, null);
}

Answer 3

Sí lo es:

 /// <summary>
/// Returns a _private_ Property Value from a given Object. Uses Reflection.
/// Throws a ArgumentOutOfRangeException if the Property is not found.
/// </summary>
/// <typeparam name="T">Type of the Property</typeparam>
/// <param name="obj">Object from where the Property Value is returned</param>
/// <param name="propName">Propertyname as string.</param>
/// <returns>PropertyValue</returns>
public static T GetPrivatePropertyValue<T>(this object obj, string propName)
{
if (obj == null) throw new ArgumentNullException("obj");
PropertyInfo pi = obj.GetType().GetProperty(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
if (pi == null) throw new ArgumentOutOfRangeException("propName", string.Format("Property {0} was not found in Type {1}", propName, obj.GetType().FullName));
return (T)pi.GetValue(obj, null);
}
/// <summary>
/// Returns a private Property Value from a given Object. Uses Reflection.
/// Throws a ArgumentOutOfRangeException if the Property is not found.
/// </summary>
/// <typeparam name="T">Type of the Property</typeparam>
/// <param name="obj">Object from where the Property Value is returned</param>
/// <param name="propName">Propertyname as string.</param>
/// <returns>PropertyValue</returns>
public static T GetPrivateFieldValue<T>(this object obj, string propName)
{
if (obj == null) throw new ArgumentNullException("obj");
Type t = obj.GetType();
FieldInfo fi = null;
while (fi == null && t != null)
{
fi = t.GetField(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
t = t.BaseType;
}
if (fi == null) throw new ArgumentOutOfRangeException("propName", string.Format("Field {0} was not found in Type {1}", propName, obj.GetType().FullName));
return (T)fi.GetValue(obj);
}
/// <summary>
/// Sets a _private_ Property Value from a given Object. Uses Reflection.
/// Throws a ArgumentOutOfRangeException if the Property is not found.
/// </summary>
/// <typeparam name="T">Type of the Property</typeparam>
/// <param name="obj">Object from where the Property Value is set</param>
/// <param name="propName">Propertyname as string.</param>
/// <param name="val">Value to set.</param>
/// <returns>PropertyValue</returns>
public static void SetPrivatePropertyValue<T>(this object obj, string propName, T val)
{
Type t = obj.GetType();
if (t.GetProperty(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance) == null)
throw new ArgumentOutOfRangeException("propName", string.Format("Property {0} was not found in Type {1}", propName, obj.GetType().FullName));
t.InvokeMember(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.SetProperty | BindingFlags.Instance, null, obj, new object[] { val });
}
/// <summary>
/// Set a private Property Value on a given Object. Uses Reflection.
/// </summary>
/// <typeparam name="T">Type of the Property</typeparam>
/// <param name="obj">Object from where the Property Value is returned</param>
/// <param name="propName">Propertyname as string.</param>
/// <param name="val">the value to set</param>
/// <exception cref="ArgumentOutOfRangeException">if the Property is not found</exception>
public static void SetPrivateFieldValue<T>(this object obj, string propName, T val)
{
if (obj == null) throw new ArgumentNullException("obj");
Type t = obj.GetType();
FieldInfo fi = null;
while (fi == null && t != null)
{
fi = t.GetField(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
t = t.BaseType;
}
if (fi == null) throw new ArgumentOutOfRangeException("propName", string.Format("Field {0} was not found in Type {1}", propName, obj.GetType().FullName));
fi.SetValue(obj, val);
}

Answer 4

 //mock class
public class Person{
public string Name{get; internal set;}
}
// works for all types, update private field through reflection
public static T ReviveType<T>(T t, string propertyName, object newValue){
// add a check here that the object t and propertyName string are not null
PropertyInfo pi = t.GetType().GetProperty(propertyName, BindingFlags.Public | BindingFlags.Instance);
pi.SetValue(t, newValue, null);
return t;
}
// check the required function
void Main()
{
var p = new Person(){Name="John"};
Console.WriteLine("Name: {0}",p.Name);
//box the person to object, just to see that the method never care about what type you pass it
object o = p;
var updatedPerson = ReviveType<Object>(o, "Name", "Webber") as Person;
//check if it updated person instance
Console.WriteLine("Name: {0}",updatedPerson.Name);
}
// Console Result: -------------------
Name: John
Name: Webber

Answer 5

t.GetProperty("CreatedOn")
.SetValue(obj, new DateTime(2009, 10, 14), null);

EDITAR: dado que la propiedad en sí misma es pública, aparentemente no necesita usar BindingFlags.NonPublic para encontrarla. Llamar a SetValue pesar de que el setter tenga menos accesibilidad sigue haciendo lo que esperas.