CODEWITHSUNDEEP
c#reflection
Marc
Marc

Reputation: 13184

Cast a value and set a property using reflection

I am trying to set a property of an object dynamically. The method takes a parameter of type object and sets the property of the object using PropertyInfo.SetValue().

public void SetValue(object value)
{
    var valueType = value.GetType();

    // Passes
    if (!_propertyInfo.PropertyType.IsAssignableFrom(valueType)) return;
    var valueType = value.GetType(); 

    // Tried but this doesn't help
    // var value = (dynamic) value;     

    // Fails   
    _propertyInfo.SetValue(value, Element, null);        
}

Pretty basic, as you can see. However, I keep getting a TargetException because object has the wrong type.

Additional information: Object does not match target type.

Exception

I don't know if this refers to the value or the object whose property I want to set. Both definitely are of the expected types. However, value is passed in as object and Element is passed in as a base type of the DeclaringType of the property info.

Is that the cause for the problem? How can I workaround this limitation, if the concrete type of Element is unknown?

Upvotes: 0

Views: 1314

Answers (2)

Jeppe Stig Nielsen
Jeppe Stig Nielsen

Reputation: 61912

Change

if (!_propertyInfo.PropertyType.IsAssignableFrom(valueType)) return;

into

if (!_propertyInfo.DeclaringType.IsAssignableFrom(valueType)) return;

In the example

abstract class Vehicle
{
    public int NumberOfWheels { get; set; }
}

the PropertyType is int while the DeclaringType is Vehicle.

This answer assumed you really wanted value to be the target object. As others have realized, you probably meant Element to be the target. In that case your IsAssignableFrom was correct, you just needed to swap the arguments to SetValue (see Vlad's answer).

Upvotes: 1

Vlad
Vlad

Reputation: 1439

See SetValue method. You should swap value and object parameters:

_propertyInfo.SetValue(Element, value, null);

Upvotes: 3

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