How to update only one field using Entity Framework?

Question

Here\'s the table

Users

UserId
UserName
Password
EmailAddress

and the code..

Answer 1

I'm late to the game here, but this is how I am doing it, I spent a while hunting for a solution I was satisified with; this produces an UPDATE statement ONLY for the fields that are changed, as you explicitly define what they are through a "white list" concept which is more secure to prevent web form injection anyway.

An excerpt from my ISession data repository:

public bool Update(T item, params string[] changedPropertyNames) where T 
  : class, new()
{
    _context.Set().Attach(item);
    foreach (var propertyName in changedPropertyNames)
    {
        // If we can't find the property, this line wil throw an exception, 
        //which is good as we want to know about it
        _context.Entry(item).Property(propertyName).IsModified = true;
    }
    return true;
}

This could be wrapped in a try..catch if you so wished, but I personally like my caller to know about the exceptions in this scenario.

It would be called in something like this fashion (for me, this was via an ASP.NET Web API):

if (!session.Update(franchiseViewModel.Franchise, new[]
    {
      "Name",
      "StartDate"
  }))
  throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.NotFound));