Adding to ObservableCollection

Question

If I have a observablecollection in a page that inserts items on a listview. How can I add to that same observablecollection(listview) from a different window(class)? I do not want to use INotifyPropertyChanged and all that. All I'm trying to do is add a item to the existing listview. I have tried literally everything and I can't figure it out. Please any help is appreciated.

CampersPage...(BindingCamper is just my way of basically saying new ObservableCollection()

  public partial class CampersPage : Page
{
    MainWindow _parentForm;
    public GridViewColumnHeader currentColumnSorted = null;
    private SortAdorner currentAdorner = null;
    String request1;
    String request2;
    String request3;
    String request4;
   // public ObservableCollection<Camper> Campers { get; private set; }


    public CampersPage(MainWindow parent)
    {
        _parentForm = parent;
        InitializeComponent();
        _parentForm.bindings = new BindingCamper();

        for (int i = 0; i < _parentForm.allCampers.Count; i++)
        {


            if (_parentForm.allCampers[i].getRequest(1) != null && _parentForm.allCampers[i].getRequest(2) != null && _parentForm.allCampers[i].getRequest(3) != null && _parentForm.allCampers[i].getRequest(4) != null)
            {
                request1 = _parentForm.allCampers[i].getRequest(1).getName();
                request2 = _parentForm.allCampers[i].getRequest(2).getName();
                request3 = _parentForm.allCampers[i].getRequest(3).getName();
                request4 = _parentForm.allCampers[i].getRequest(4).getName();

            }

            _parentForm.bindings.Campers.Add(new Camper { FirstName = "" + _parentForm.allCampers[i].getFirstName(), LastName = "" + _parentForm.allCampers[i].getLastName(), Ages = _parentForm.allCampers[i].getAge(), SchoolGrade = _parentForm.allCampers[i].getGrade(), Gender = "" + _parentForm.allCampers[i].getGender(), bindingRequest1 = request1, bindingRequest2 = request2, bindingRequest3 = request3, bindingRequest4 = request4 });
            //DataContext = _parentForm.bindings;
        }

        DataContext = _parentForm.bindings;



    }

---Now I click on a button and a new window comes up where I would like to add a new camper to the listview in CampersPage.

      public partial class AddNewCamper : Window
{
    MainWindow _parentForm;


    public AddNewCamper(MainWindow parentForm)
    {
        InitializeComponent();
        _parentForm = parentForm;
       // _parentForm.bindings = new BindingCamper();

    }private void btnSubmitNewCamper_Click(object sender, RoutedEventArgs e)
    {
        String firstName = txtNewFirstName.Text;
        String lastName = txtLastName.Text;

        int age;
        int grade;
        String newage = comboNewAge.Text;
        if (firstName != "" && lastName != "" && IsNumber(txtNewGrade.Text) && newage != "")
        {
            age = Convert.ToInt16(newage);
            grade = Convert.ToInt16(txtNewGrade.Text);

            // Create New Camper
            Camper person = new Camper(age, grade, boxNewGender.Text, firstName, lastName);

            _parentForm.allCampers.Add(person);
            //This is just adding the camper to the listview. Not sure if it is actually adding it to the database.
            _parentForm.bindings.Campers.Add(new Camper { FirstName = person.getFirstName(), LastName = person.getLastName(), Ages = person.getAge(), SchoolGrade = person.getGrade() });
            //CampersPage p = new CampersPage(_parentForm);
            DataContext = _parentForm.bindings;

Do I have to somehow add AddNewCamper's namespace to CampersPage's namespace in xaml?

   <ListView  HorizontalAlignment="Stretch" Margin="0,12" x:Name ="listViewCampers" ItemsSource="{Binding Campers}" DisplayMemberPath="bindMe" IsSynchronizedWithCurrentItem="True" Grid.Column="1">

ObservableCollection class:

      public partial class BindingCamper  
{  // This class assist in binding campers from listview to the textboxes on the camperspage
    public ObservableCollection<Camper> Campers { get; set; }
    public ObservableCollection<Staff> StaffMembers { get; set; }
    public ObservableCollection<Schedule> schedule { get; set; }
    public ObservableCollection<Group> Groups { get; set; }



   public BindingCamper()
    {
      Campers = new ObservableCollection<Camper>();
      StaffMembers = new ObservableCollection<Staff>();
      schedule = new ObservableCollection<Schedule>();
      Groups = new ObservableCollection<Group>();

   }

Answer 1

I won't go as far as claiming you're using WPF wrong, but you're certainly making your life difficult. I suggest reading up a bit on MVVM pattern - it really makes WPF development easier (here's good starting article).

Approach you're using at the moment is not correct on several levels:

• your windows/pages need to have way too much knowledge about each other to work properly
• result of which, is dependency on parent form in your child windows (while what you really need is dependency on window context, which in fact is campers list)
• you need to do too much manual notifications/setting up to achieve your goals (while WPF has great tools to do it automatically)
• you seem to be exposing model (allCampers) through view (MainWindow)

All of this can be solved with a bit of redesigning:

1. Your views (Main, CampersPage, AddNewCamper) should be dependent on BindingCamper class (which essentially could be view model for them), not on each other
2. Same instance of BindingCamper should be set as DataContext for all of them
3. You should not add bindings manually (like you're doing now); all can (and should) be done from XAML

Having above in mind, your CampersPage class should look like this:

public partial class CampersPage : Page
{
    public CampersPage(BindingCamper camper)
    {
        InitializeComponent();
        DataContext = camper;
    }
}

It should by no means initialize data for parent window and set it's binding. This is simply wrong.

Actually, this approach (providing data context through constructor) can be used in all your view classes (AddNewCamper and MainWindow too, probably).

Now, when you need campers page, say from your main window, it gets very easy:

public partial class MainWindow : Window
{
    public void ShowCampers()
    {
        var campersPage = new CampersPage((BindingCampers) this.DataContext);
        // show campersPage
    }
}

It is the same with AddNewCamper window. Just pass it data context. When you add new camper, add it to BindingCamper.Campers list (which is available through data context):

// rest of the btnSubmitNewCamper_Click method elided
Camper person = new Camper(age, grade, boxNewGender.Text, firstName, lastName);
((BindingCamper)this.DataContext).Campers.Add(person);

That's all. Thanks to combined mechanisms of data binding and observable collection, this new element will immediately be visible both in MainWindow and CampersPage.

Edit:

Code to fetch campers from database should be wrapper with some kind of DAO object (as a part of DAL - I know, lot of ugly buzzwords, but luckily they are all related and fairly obvious). For example, you can have a class that will deal with getting campers from database:

public class CampersProvider
{
    public IEnumerable<Camper> GetAllCampers()
    {
        // here you put all your code for DB interaction
        // and simply return campers
    }
}

To give you quick solution, you can once again pass CampersProvider to MainWindow constructor, call GetAllCampters method and build observable collection for BindingCamper. However, this is not very MVVM approach. Those stuff usually is handled by view model (yet another, separate class), which at the moment you don't have.

Code you posted requires quite some work, I think it won't be a bad idea if you read a bit about MVVM pattern and try to apply it to your application.