Windows Presentation Foundation (Avalon) Databinding to objects

Article
09/30/2005

Databinding to an object datasource is really simple in Windows Presentation Foundation. I didn't find any good samples around, so I'm posting some code here to help you save some time.

My scenarion is really simple, I would like to create an WPF application to visualize my DVD collection. The code also shows how to bind an Image control i WPF to an JPEG image stored inside the SQL Server database (not just a pointer to a file). The code is simplified to only illustrate the main concepts and I have not worked with the design part yet.

First I start with a class to represent the information about a DVD title:

public class Dvd
{

        int _dvdId;
        private string _title;
        private byte[] _frontCover;

public int Id { get { return _dvdId; } }

public string Title { get { return _title; } }

        public BitmapFrame FrontCover
        {
            get
            {
                BitmapFrame frontCover = System.Windows.Media.Imaging.BitmapFrame.Create(new System.IO.MemoryStream(_frontCover));

                return frontCover;
            }
        }

        public Dvd(
            int id,
            string title,
            byte[] frontCover)
        {
            _dvdId = id;
            _title = title;
            _frontCover = frontCover;
        }

}

The Data Access Layer contains a method to return a list DVD's from the database:

        public static List<Dvd> GetTitles()
        {
            OdbcConnection connection = new OdbcConnection(m_connectionString);

            string selectCommand = @"
                SELECT     DvdId, Title, FrontCover
                FROM         Titles";

OdbcCommand command = new OdbcCommand(selectCommand, connection);

List<Dvd> titles = new List<Dvd>();

            connection.Open();
            OdbcDataReader reader = command.ExecuteReader();
            while (reader.Read())
            {
                Dvd dvd = new Dvd(
                    Convert.ToInt32(reader["DvdId"]),
                    Convert.ToString(reader["Title"]),
                    (byte[])reader["FrontCover"]);

titles.Add(dvd);

}

return titles;
}

Then we have the DvdCollection class which includes a method to return a list of Dvd objects:

using System;
using System.Collections.Generic;
using System.Text;
using DvdLibrary.BusinessEntities;
using DvdLibrary.DataAccessLayer;

namespace DvdLibrary.BusinessLogicLayer
{
    public class DvdCollection
    {
        public static List<Dvd> GetTitles()
        {
            return TitlesDAL.GetTitles();
        }

}
}

Then in the XAML code-behind, I have this code to retrieve a a list of DVD titles from the business logic layer:

private void OnInit(object sender, EventArgs e)
{
List<Dvd> titles = DvdCollection.GetTitles();

DvdList.DataContext = titles;
}

Finally we have the XAML file showing how to do the Databind to the list of DVD titles using a ListBox:

<?Mapping XmlNamespace="DvdLibrary_BusinessLogicLayer" ClrNamespace="DvdLibrary.BusinessLogicLayer" Assembly="DvdLibrary"?>
<Grid
xmlns="https://schemas.microsoft.com/winfx/avalon/2005"
xmlns:x="https://schemas.microsoft.com/winfx/xaml/2005"
xmlns:c="https://schemas.microsoft.com/winfx/markup-compatibility/2005"
xmlns:d="https://schemas.microsoft.com/expression/interactivedesigner/2005"
c:Ignorable="d"
Background="#FFFFFFFF"
x:Name="DocumentRoot"
Width="640"
Height="480"
x:Class="DvdBrowser.Scene1"
Loaded="OnInit"
>

<Grid.Resources>
<ResourceDictionary>
<Storyboard x:Key="OnLoaded" FillBehavior="HoldEnd" BeginTime="{x:Null}" />

</ResourceDictionary>
</Grid.Resources>

<Grid.Triggers>
<EventTrigger RoutedEvent="FrameworkElement.Loaded">
<EventTrigger.Actions>
<BeginStoryboard x:Name="OnLoaded_BeginStoryboard" Storyboard="{DynamicResource OnLoaded}"/>
</EventTrigger.Actions>
</EventTrigger>
</Grid.Triggers>

Windows Presentation Foundation (Avalon) Databinding to objects

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