CODEWITHSUNDEEP
c#wpfentity-frameworkbinding
Wiktor Czarnecki
Wiktor Czarnecki

Reputation: 11

WPF<-> entity binding

I have problem with updating data from my datasource(database through entity fw) to wpf-windows. I generate files using entity framework, so i'm accesing data from datebase this way:

public partial class sampleWindow : Window
    {
        myEntity en = new myEntity();
        public sampleWindow()
        {
            InitializeComponent();
            Bind();
        }

        private void Bind()
        {
            var list = from o in en.table select o;
            someDatagrid.ItemsSource = list.ToList();
        }

This method, firstly, was adequate for my program, i was refreshing 'Bind' method after i was doing some operations on database, so the data in my datagrids or combos was fresh. The problem occurs when i was changing database in diffrent wpf-windows. I have read that I should implement observable interface and use load instead of itemsSource. I tried to do it but i'm begginer and my attempts faild miserably. Could someone tell me step by step, what i should do?

Upvotes: 1

Views: 74

Answers (3)

E-Bat
E-Bat

Reputation: 4892

There are so many and better ways (MVVM pattern) to accomplish this than your approach. To keep it simple it can be accomplished this way:

 //Gets the Load() extention method available for DbSet
    using System.Data.Entity;

        private void Bind()
        {
            myEntity.table.Load();
            /*Local returns an obvervable collection convenient for data binding. 
            This is a synchronized local view of your data. It means any item added , deleted and updated will be reflected in your controls.*/
            var obsColl = myEntity.table.Local;
            someDatagrid.ItemsSource = obsColl;
        }

Upvotes: 0

mrsargent
mrsargent

Reputation: 2442

You would want to use a singleton for the instance of your entity as The Sharp Ninja mentioned. His article in the link he posted does a good job of explaining. You will want to use an observable collection to bind your ItemSource to. When an item is added or removed from an Observable collection the UI is automatically notified. The problem you are going to have is that there is not a .ToObservableCollection() extension method build in to .net so you will have to implement your own.

I use this extension method

 public static ObservableCollection<T> ToObservableCollection<T>(
        this IEnumerable<T> enumeration)
    {
        return new ObservableCollection<T>(enumeration);
    }

So now your bind method can set your ItemSource to the observable collection

private void Bind()
    {
        var list = from o in en.table select o;
        someDatagrid.ItemsSource = list.ToObservableCollection();
    }

Upvotes: 0

The Sharp Ninja
The Sharp Ninja

Reputation: 1041

You need a Singleton to manage your data, combined with using an ObservableCollection to expose the data. When the collection is changed by any view, it will notify any subscribers to the observation and they will automatically update.

See: Example of bindable list in XAML app (first part) Example of Singleton

Upvotes: 1

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