.NET Complex binding revert changes

Question

I was doing some test about complex .NET databinding, and i need to have some advice in order to rollback changes made by the user. Let's assume, for example, that i've got 2 classes in my BL layer:

"Person" represent the core person object:

internal class Person{
  public String Name{get; set;}            
  public String Surname{get; set;}
  public int Age { get; set; }
 }

"PeopleList" represent the list of person object:

internal class PeopleList : List<Person> {

//Let's assume that this class has a whole bunch of function with a complex business logic in it.

    public Person[] getPeopleByName(String name)
    {
        return this.Where(x => String.Compare(name, x.Name, true) == 0).ToArray(); 
    }

    public Person[] getPeopleByAge(int age)
    {
        return this.Where(x => x.Age.Equals(age)).ToArray();
    }
}

Now i want to let user edit an instance of a PeopleList object through a form with a DataGridView. So i created a windows form application and in Load() event i did this:

 private void frmTest_Load(object sender, EventArgs e)
        {

            //Intialize _peopleList object 
            _peopleList = new PeopleList();
            this.initializePeopleWithTestData();

            //Initialize _peopleBindingList by passing PeopleList (it inherits from List<Of ?> and it implements IList interface)
            this._peopleBindingList = new BindingList<Person>( _peopleList);

            //Initialize _peopleBindingSource 
            this._peopleBindingSource = new BindingSource();
            this._peopleBindingSource.DataSource = this._peopleBindingList;
            this._peopleBindingSource.SuspendBinding(); //Let's suspend binding to avoid _peopleList to be modified. 

            //Set peopleBindingList as DataSource of the grid
            this.dgwPeople.DataSource = _peopleBindingSource;
        }

With the above-mentioned code i can see/edit/delete/add people in dgwPeople (that's my datagridview) without problem, but even if i called "SuspendBinding()" over the BindingSource, if the user edits the grid, the binding system immediately affects the data contained into my _peopleList object! And this is not good because in this way i loose the original version of my data and i can't rollback them no more if the user decide to cancel changes.!

In the simple binding there's a fantastic attribute "DataSourceUpdateMode" that let me decide when the binding has to affect the datasource. If i set it to "Never" i have to call explicitly the Write() method to commit changes. Is there something similar for the complex binding?

How can i avoid binding to affect my original data immediately in complex binding? Is there any way to rollback changes (apart from keep a clone copy of the original object)? Is there any pattern that helps in handling this kind of situations?

You can download my test solution (VS2012) here

Thanks in advance!

Answer 1

internal class Person, iNotifyPropertyChanged
{
  // todo implement NotifyPropertyChanged 
  private string name;
  private string nameOrig;
  public String Name
  {
     get {return name; } 
     set 
     {
        if (name == value) return;
        name = value;
        NotifyPropertyChanged("Name");
     }
  }
  public void RollBack() { Name = nameOrig; }
  public void CommitChanges()  {  nameOrig = name; }            
  public Person (string Name) { name = Name; nameOrig = name; }
}