Binding data from Linq Database using Observable Collection - WP8 - windows-phone-8

Question

I'm saving some data in a database using linq. I have a DAO class, where I put all my CRUD methods, and I have another class where I define my table and its columns.
[Table(Name = "CONTACTS")]
public class UserContacts
{
private int _id;
[Column(Name = "ID", IsPrimaryKey = true, IsDbGenerated = true, CanBeNull = false, AutoSync = AutoSync.OnInsert)]
public int ID
{
get { return _id; }
set { _id = value; }
}
private string _name;
[Column(Name = "NAME", CanBeNull = false)]
public string NAME
{
get { return _name; }
set { _name = value; }
}
private string _number;
[Column(Name = "NUMBER", CanBeNull = false)]
public string NUMBER
{
get { return _number; }
set { _number = value; }
}
}
DAO Class
public class DAOUserContacts
{
public IList<UserContacts> list = new List<UserContacts>();
public IList<UserContacts> GetData()
{
try
{
using (DataBaseContext db = new DataBaseContext(DataBaseContext.ConnectionString))
{
list = (from info in db.UserContacts orderby info.COLUMN_NAME ascending select info).ToList();
}
return list;
}
catch (Exception)
{
return null;
}
}
// Other methods
}
I'm showing all data stored in this database in a LongListSelector.
In Main.cs constructor
llsContacts.DataContext = new DAORUserContacts().GetData();
In Main.xaml
<phone:LongListSelector x:Name="llsContacts" ItemsSource="{Binding}" >
<phone:LongListSelector.ItemTemplate>
<DataTemplate>
<ListBoxItem local:TiltEffect.IsTiltEnabled="true">
<Grid Margin="0" >
<TextBlock Text="{Binding NAME}" FontFamily="Segoe WP" FontSize="28" Margin="77,0,0,0" />
<TextBlock Text="{Binding NUMBER}" FontFamily="Segoe WP Light" FontSize="17" Margin="77,33,0,0"/>
</Grid>
</ListBoxItem>
</DataTemplate>
</phone:LongListSelector.ItemTemplate>
</phone:LongListSelector>
I made a research on internet, and found about ObservableCollection, and I want to use it. I read this article http://www.codeproject.com/Articles/80555/Databinding-in-Silverlight-applications#_Toc261149245 to understand how it works, but I still have some doubts.
On this article, was created an Employee that inherits from INotifyPropertyChanged, and an Emplyees that inherits from ObservableCollection.
In my case, I want that my list (on xaml) always shows what is in database.
Is OK inheriting my UserContacts from INotifyPropertyChanged? Because this class declares a Table...
And should my DAOClass inherits from ObservableCollection? Or just my GetData() returns a ObservableCollection instead of a List?
Another thing.. there is a button that, when the user press, updates the database (search all the contacts on device, and remove from database what had been removed in phone, and add to database what had been add in phone).
Using ObservableCollection, when the search for contacts finishes, and my database is updated, should I call something to update the LongListSelector on xaml? Or after the database update, the LongListSelector is automatically updated too?
Thanks...

Answer 1

User viewmodel for assigning data context and assign observable collection at xaml side as binding.And viewmodel should have observable collection which you use for binding.Then if you made any changes for the collection automatically updates the longlistselector.
Every time you should change the collection according to your database changes.