Question

I have the following class that’s used by my MVC3 application. I would like
to simplify the updating of the class so that when a new class object is
created then the Created and CreatedBy fields get set automatically.

I’d also like to make it so that the Modified and ModifiedBy fields get
updated automatically.

Is there a way that I could do this?

The class is used in MVCnamespace Storage.Models
{
    public class Topic : TableServiceEntity
    {
        [DisplayName("Partition Key")]
        public override string PartitionKey { get; set; }
        [DisplayName("Row Key")]
        public override string RowKey { get; set; }
        [DisplayName("Description")]
        public string Description { get; set; }
        public DateTime Created { get; set; }
        public DateTime Modified { get; set; }
        public String CreatedBy { get; set; }
        public string ModifiedBy { get; set; }
    }
}

Answer 1

jonathan,

Jason’s answer above with the logic contained within the constructors is a perfectly valid and clean way of doing this and I wouldn’t argue with that (and have done it myself for more ‘static’ properties). However, given that there could be a timelapse between the creation of the object and the actual save, then you may also want to consider putting this logic into your controller (or service layer).

this would look roughly like this:

public ActionResult Create(MyCreateViewModel viewModel)
{
    if (ModelState.IsValid)
    {
        viewModel.Entity.Created = DateTime.UtcNow;
        _myService.Insert(viewModel.Entity);
        _myService.SaveChanges();
        return this.RedirectToAction(x => x.Index());
    } else {
        PopulateViewModel(viewModel);
        return View(viewModel);
    }
}

likewise, you may have a LastEdit datetime that you want to track. use the Edit action similarly:

public ActionResult Edit(MyEditViewModel viewModel)
{
    if (ModelState.IsValid)
    {
        viewModel.Entity.LastEditDate= DateTime.UtcNow;
        _myService.AttachAndUpdate(viewModel.Entity);
        _myService.SaveChanges();
        return this.RedirectToAction(x => x.Index());
    } else {
        PopulateViewModel(viewModel);
        return View(viewModel);
    }
}

just another approach to ensure that datetime related properties are truly reflected.