Partially updated object with EF Code First and ASP.NET MVC

Question

EF4.1-Code-First-Gurus!

I wonder if there is a more elegant way to handle the following ASP.NET MVC 3 EF 4.1 Code First script: Let's say we have the following POCOs:

public class Entity { [Key] public int Id { get; set; } [ScaffoldColumn(false)] public DateTime CreatedOn { get; set; } [ScaffoldColumn(false)] public DateTime ModifiedOn { get; set; } } 

and

 public class Person : Entity { public string FirstName { get; set; } public string LastName { get; set; } public DateTime Birthday { get; set; } } 

Suppose we have created some standard types of editing that do not include the CreateOn / ModifiedOn fields, since they will be installed in the repository, and not by the user.

In my repository, I have the following update method. Methods exclude the list of fields that need to be updated (leaving the CreateOn / ModifiedOn fields selected):

  public void Update(Person person, List<string> properties) { Person tmpPerson = context.People.Single(x => x.Id == person.Id); context.People.Attach(tmpPerson); foreach (PropertyDescriptor descriptor in TypeDescriptor.GetProperties(person)) { if (properties.Contains(descriptor.Name)) descriptor.SetValue(tmpPerson, descriptor.GetValue(person)); } tmpPerson.ModifiedOn = DateTime.Now; } 

The controller now calls this method as follows:

  [HttpPost] public ActionResult Edit(Person person) { if (ModelState.IsValid) { personRepository.Update(person, new List<string> { "FirstName", "LastName", "Birthday"}); personRepository.Save(); return RedirectToAction("Index"); } else { return View(); } } 

It all works like a charm. However, I really do not like that I have to specify the fields manually. How would you handle this requirement? Of course, I could add CreateOn / ModifiedOn fields as hidden fields to the view, but I don’t want to unload the form by many (there are much more fields).

Perhaps this is a similar question: How to update an EF 4 object in ASP.NET MVC 3?

I appreciate your help! Joris

Answer 1

Yes, there is a more elegant version:

 public void Update(Person person, params Expression<Func<Person,object>>[] properties) { context.People.Attach(person); DbEntityEntry<Person> entry = context.Entry(person); foreach (var property in properties) { entry.Property(property).IsModified = true; } person.ModifiedOn = DateTime.Now; } 

You will call the method as follows:

 [HttpPost] public ActionResult Edit(Person person) { if (ModelState.IsValid) { personRepository.Update(person, p => p.FirstName, p => p.LastName, p => p.Birthday); personRepository.Save(); return RedirectToAction("Index"); } else { return View(person); } }