Setting C# property value when you know its class name (not property name)

Question

I have a class as follows:

  public class DummyReturnDto
  {
      public Set1ReturnDto Foo { get; set; }
      public Set2ReturnDto Bar { get; set; }

      public DummyReturnDto()
      {
          Set1 = new Set1ReturnDto();
          Set2 = new Set2ReturnDto();
      }
  }

where all the properties are guaranteed to have classes as their types and will be unique. I would like to use reflection to set the value for the property given a particular type. So for Set1ReturnDto:

var propertyInfo = obj.GetType().GetProperty(Set1ReturnDto, ??????);
propertyInfo.SetValue(obj, value, null);

and then for Set2ReturnDto

var propertyInfo = obj.GetType().GetProperty(Set2ReturnDto, ??????);
propertyInfo.SetValue(obj, value, null);

EDIT:

This is part of the needed knowledge to implement requirements for Generic approach to dealing with multiple result sets from EF stored procedure

Are you sure that every type occurs just once within your class DummyReturnDto? — MakePeaceGreatAgain
– MakePeaceGreatAgain, Commented Jul 14, 2015 at 5:52
Why use reflection for this? Can't you just keep an internal dictionary from type to instance and make the getters and setters delegate to that dictionary? What are you trying to achieve? Reflection is very rarely the solution. — Vincent van der Weele
– Vincent van der Weele, Commented Jul 14, 2015 at 6:46
@Vincent Ultimately I will be passing in a List of classes to my method using this. The ordering of the classes (not object instances) will be deliberate as I need to extract multiple result sets out of what is returned from the database and map them onto each dataset. See stackoverflow.com/questions/31399498/… and ultimately the link I post in my original post. — TheEdge
– TheEdge, Commented Jul 14, 2015 at 10:11
To me it seems easier then to create an interface with a single method SetProperty(Type t, object o) and use that in your helper class rather than the generic type T (which removes the need for reflection). DummyReturnDto should implement that interface by having a dictionary from Type to object. All the getters do something like Set1ReturnDto Foo { get { return (Set1ReturnDto)_dict[typeof(Set1ReturnDto)]; } }. That would solve this problem, right? — Vincent van der Weele
– Vincent van der Weele, Commented Jul 14, 2015 at 17:15

Rob · Accepted Answer · 2015-07-14 05:50:14Z

4

This will do it:

var propertyInfo = typeof(DummyReturnDto).GetProperties()
                       .Single(p => p.PropertyType == typeof(Set1ReturnDto));

answered Jul 14, 2015 at 5:50

Rob♦

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2 Comments

MakePeaceGreatAgain Over a year ago

This assumes that every type occurs just once within the class. If this is not the desired behaviour (which isn´t clear from the tgread), you´d may change the .Single-part accordingly.

Rob Over a year ago

@HimBromBeere You're right, I based my solution on are guaranteed to have classes as their types and will be unique :)

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