How to set value of property where there is no setter

Question

I have seen various questions raised and answered where we can invoke a private setter using reflection such as this one:

Is it possible to get a property's private setter through reflection?

However I have some code which has a property i need to set but cant because there is no setter, I cant add a setter as this isn't my code. Is there a way to somehow set the value using reflection in this scenario?

Answer 1

I do not suggest doing this on your application but for testing purpose it may be usefull...

Assuming you have:

public class MyClass
{
     public int MyNumber {get;}
}

You could do this if its for test purpose, I would not suggest to use this in your runtime code:

var field = typeof(MyClass).GetField("<MyNumber>k__BackingField", BindingFlags.Instance | BindingFlags.NonPublic);
field.SetValue(anIstanceOfMyClass, 3);

Answer 2

You have to keep in mind that a property is just syntactic sugar for a pair of methods. One method (the getter) returns a value of the property type and one method (the setter) accepts a value of the property type.

There is no requirement that the getter and setter actually get or set anything. They're just methods, so they're allowed to do anything. The only requirement is that the getter return a value. From the outside there's no way you can really tell if there is a backing field. The getter could be getting computed every time it's called. It may be based on other properties.

So, no, there isn't really any way in general to "set" a property that doesn't have a setter.