Question

I have two C# classes that have many of the same properties (by name and type). I want to be able to copy all non-null values from an instance of Defect into an instance of DefectViewModel. I was hoping to do it with reflection, using GetType().GetProperties(). I tried the following:

var defect = new Defect();
var defectViewModel = new DefectViewModel();

PropertyInfo[] defectProperties = defect.GetType().GetProperties();
IEnumerable<string> viewModelPropertyNames =
    defectViewModel.GetType().GetProperties().Select(property => property.Name);

IEnumerable<PropertyInfo> propertiesToCopy =
    defectProperties.Where(defectProperty =>
        viewModelPropertyNames.Contains(defectProperty.Name)
    );

foreach (PropertyInfo defectProperty in propertiesToCopy)
{
    var defectValue = defectProperty.GetValue(defect, null) as string;
    if (null == defectValue)
    {
        continue;
    }
    // "System.Reflection.TargetException: Object does not match target type":
    defectProperty.SetValue(viewModel, defectValue, null);
}

What would be the best way to do this? Should I maintain separate lists of Defect properties and DefectViewModel properties so that I can do viewModelProperty.SetValue(viewModel, defectValue, null)?

Edit: thanks to both Jordão’s and Dave’s answers, I chose AutoMapper. DefectViewModel is in a WPF application, so I added the following App constructor:

public App()
{
    Mapper.CreateMap<Defect, DefectViewModel>()
        .ForMember("PropertyOnlyInViewModel", options => options.Ignore())
        .ForMember("AnotherPropertyOnlyInViewModel", options => options.Ignore())
        .ForAllMembers(memberConfigExpr =>
            memberConfigExpr.Condition(resContext =>
                resContext.SourceType.Equals(typeof(string)) &&
                !resContext.IsSourceValueNull
            )
        );
}

Then, instead of all that PropertyInfo business, I just have the following line:

var defect = new Defect();
var defectViewModel = new DefectViewModel();
Mapper.Map<Defect, DefectViewModel>(defect, defectViewModel);

Answer 1

Take a look at AutoMapper.