Compare 2 object of the same class

Question

Recently, I ran into a problem of comparing 2 objects of the same class in C#. I need to know which fields/properties are changed.

Here is the example:

SampleClass 
{
  string sampleField1;
  int sampleField2;
  CustomClass sampleField3; 
}

And I have 2 SampleClass object, object1 and object2, for example. These 2 objects have some different field value.

• Can anyone know the best approach to get which fields are different?

• And how to get the (string) names of that different fields/properties?

• I heard of Reflection in .Net. Is that the best approach in this situation?
• And if we didn't have the CustomClass field? (I just make this field for a more general approach, that field does not exist in my case)

Answer 1

If you want Generic way to get all changed properties

you can use this method (and it is using reflection ^_^ )

    public List<string> GetChangedProperties(object obj1, object obj2)
    {
        List<string> result = new List<string>();

        if(obj1 == null || obj2 == null )
            // just return empty result
            return result;

        if (obj1.GetType() != obj2.GetType())
            throw new InvalidOperationException("Two objects should be from the same type");

        Type objectType = obj1.GetType();
          // check if the objects are primitive types
        if (objectType.IsPrimitive || objectType == typeof(Decimal) || objectType == typeof(String) )
            {
                // here we shouldn't get properties because its just   primitive :)
                if (!object.Equals(obj1, obj2))
                    result.Add("Value");
                return result;
            }

        var properties = objectType.GetProperties();

        foreach (var property in properties)
        {
            if (!object.Equals(property.GetValue(obj1), property.GetValue(obj2)))
            {
                result.Add(property.Name);
            }
        }

        return result;

    }

Please note that this method only gets Primitive type properties that have changed and reference type properties that refer to the same instance

EDIT: Added validation in case if obj1 or obj2 is primitive type (int,string ... ) because I tried to pass string object and it will give an error also fixed bug of checking whether the two values are equal