How to get a value from the combo box in WPF?

Question

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Hi Team

I have a combo box and its not loading the values it fetches from the table in the database, but its only showing on the grid and rectangle, when i click combo box its blank with nothing to select.

What I have tried:

XML

<UserControl.Resources>
        <CollectionViewSource x:Key="StockCodes" Source="{Binding StockCodes}"/>
        <CollectionViewSource x:Key="StockDescription" Source="{Binding Description}"/>
    </UserControl.Resources>
    
    <Grid Background="White" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Margin="0,86,-775.6,-46.6" Width="1766">
        <Label Content="Premix Material Management" BorderThickness="1.5" BorderBrush="#FF0B0B0B" Background="#FF383838" Foreground="White" FontSize="18" HorizontalContentAlignment="Center" VerticalAlignment="Top" Margin="10,10,0,0" FontWeight="SemiBold" />
         
        <!---Rectangle for Recipe Details-->
        <Rectangle  HorizontalAlignment="Left" Height="371" Stroke="#FFCFCFD1" VerticalAlignment="Top" Width="260" Margin="14,104,0,0"/>
        
        
        <!---Recipe fields-->
        <Label Content="Recipe Details" FontWeight="SemiBold"  HorizontalAlignment="Left" HorizontalContentAlignment="Center" VerticalAlignment="Top" Width="260" BorderBrush="#FFBEBEBE" Background="#FFE3E3E3" BorderThickness="1.5" Foreground="Black" Height="30" VerticalContentAlignment="Center" FontSize="12" Margin="14,103,0,0"/>
        <Label x:Name="lblActive_Copy9" FontWeight="SemiBold" FontSize="10" Visibility="Visible" Content="IDX:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,135,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <TextBox x:Name="txtIDX" Foreground="Black" HorizontalAlignment="Left" Visibility="Visible" FontSize="10" Height="26" Margin="146,132,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy1" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="Recipe:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,163,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <TextBox x:Name="txtRecipe" Foreground="Black" FontSize="10" HorizontalAlignment="Left" Visibility="Visible" Height="26" Margin="146,160,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy13" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="Rec No:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,191,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <TextBox x:Name="txtRecNo" FontSize="10" Foreground="Black" HorizontalAlignment="Left" Visibility="Visible" Height="26" Margin="146,188,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy2" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="Description:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,220,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <TextBox x:Name="txtDescription" FontSize="10" Foreground="Black" HorizontalAlignment="Left" Visibility="Visible" Height="26" Margin="146,217,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy3" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="Batch Size:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,248,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <TextBox x:Name="txtBatchSize" FontSize="10" Foreground="Black" HorizontalAlignment="Left" Visibility="Visible" Height="26" Margin="146,245,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy4" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="Palleting Instruction:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,276,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <TextBox x:Name="txtPalletInstruction" FontSize="10" Foreground="Black" HorizontalAlignment="Left" Visibility="Visible" Height="26" Margin="146,273,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy5" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="Feed First Recipe Name:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,304,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <TextBox x:Name="txtFeedFirstName" FontSize="10" Foreground="Black" HorizontalAlignment="Left" Visibility="Visible" Height="26" Margin="146,301,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy11" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="PPA TK601:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,331,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <TextBox x:Name="txtPPATK601" ToolTip="Can only be edit if second last digit in recipe is 2"  IsReadOnly="True" TextChanged="txtPPATK601_TextChanged" FontSize="10" Foreground="Black" HorizontalAlignment="Left" Visibility="Visible" Height="26" Margin="146,328,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy12" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="PPA TK602:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,359,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <TextBox x:Name="txtPPATK602" FontSize="10" Foreground="Black" HorizontalAlignment="Left" Visibility="Visible" Height="26" Margin="146,354,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy10" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="Active:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,387,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <CheckBox x:Name="chkActive" TabIndex="3" HorizontalAlignment="Left" Checked="chkActive_Checked" Unchecked="chkActive_Unchecked" Margin="146,392,0,0" VerticalAlignment="Top" RenderTransformOrigin="-0.043,-1.119"/>
        <Button x:Name="btnAdd_Copy" Content="Save" Click="btnAdd_Click"  Background="ForestGreen" BorderBrush="ForestGreen" FontWeight="SemiBold" Visibility="Visible" HorizontalAlignment="Left" Margin="176,415,0,0" VerticalAlignment="Top" Width="90" />


        
        <!---Ingredient Totals-->
        <Rectangle  HorizontalAlignment="Left" Height="371" Stroke="#FFCFCFD1" VerticalAlignment="Top" Width="270" Margin="290,103,0,0"/>
        <Label Content="Ingredient Totals" FontWeight="SemiBold" HorizontalAlignment="Left" HorizontalContentAlignment="Center" VerticalAlignment="Top" Width="270" BorderBrush="#FFBEBEBE" Background="#FFE3E3E3" BorderThickness="1.5" Foreground="Black" Height="29" VerticalContentAlignment="Center" FontSize="12" Margin="288,104,0,0"/>
        
        <!---Ingredient fields names-->
        <Label x:Name="lblActive_Copy" FontWeight="SemiBold" Visibility="Visible" Content="Micros:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="124" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="296,135,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE" Height="23" FontSize="10"/>
        <TextBox x:Name="txtMicroTotal" FontSize="10" Foreground="Black" HorizontalAlignment="Left" Visibility="Visible" Height="20" Margin="425,138,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="lblActive_Copy7" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="Macros:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="125" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="296,163,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE" Height="23"/>
        <TextBox x:Name="txtMacroTotal" Foreground="Black" FontSize="10" HorizontalAlignment="Left" Visibility="Visible" Height="23" Margin="426,163,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="122"/>
        <Label x:Name="lblActive_Copy8" FontSize="10" FontWeight="SemiBold" Visibility="Visible" Content="Total:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="125" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="295,191,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE" Height="23"/>
        <TextBox x:Name="txtTotal" Foreground="Black" FontSize="10" HorizontalAlignment="Left" Visibility="Visible" Height="23" Margin="426,191,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="122"/>


        <pre lang="XML"><!---Recipe name and drop down box-->
        <Label x:Name="lblDriverName_Copy" FontWeight="SemiBold" Visibility="Visible" Content="Recipe Code:" HorizontalAlignment="Left" VerticalAlignment="Top" Width="179" HorizontalContentAlignment="Right" Background="#FFE3E3E3" Margin="17,65,0,0" BorderThickness="1" BorderBrush="#FFBEBEBE"/>
        <ComboBox x:Name="cbxRecipe" TabIndex="1" IsTextSearchEnabled="True"  ItemsSource="{Binding Recipe}" DisplayMemberPath="StockCodes"  IsEditable="True"    IsTextSearchCaseSensitive="False"  Foreground="Black" HorizontalAlignment="Left" Margin="207,63,0,0" VerticalAlignment="Top" Width="214" SelectionChanged="cbxRecipe_SelectionChanged">
            <ComboBox.ItemsPanel>
                <ItemsPanelTemplate>
                    <VirtualizingStackPanel />
                </ItemsPanelTemplate>
            </ComboBox.ItemsPanel>
        </ComboBox>

C#

private void UserControl_Loaded(object sender, RoutedEventArgs e)
        {
            LoadControl();

        }
        public void LoadControl()
        {
            Managers.BatchMaterialManager.SetDefaultConnection();
            presenter.PopulateComboBox();
            Properties.Settings.Default.Process = "Recipes";
            string[] arrayOil = RecipeName.Split('/');
            string OilIndicator = arrayOil[arrayOil.Length - 2].ToString();
            string LastDigit = RecipeName[RecipeName.Length - 2].ToString();
            if (OilIndicator == "2") // Has both oils in - allow split
            {
                txtPPATK601.IsReadOnly = false;
            }
        }
        private void cbxRecipe_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            LoadRecipe();
        }

        public void LoadRecipe()
        {
            TotalCrudeOilPerc = 0;
            CrudeOilPerc = 0;

            CollectionViewSource _StockCodeList = new CollectionViewSource();
            _StockCodeList = (CollectionViewSource)this.FindResource("StockCodes");

            CollectionViewSource _StockDescList = new CollectionViewSource();
            _StockDescList = (CollectionViewSource)this.FindResource("StockDescription");

            Managers.BatchMaterialManager.SetAdriotConnection();
            presenter.loadIngredients(Convert.ToInt32(cbxRecipe.SelectedValue), _StockCodeList, _StockDescList);
            presenter.PopulateTotals();
            presenter.loadRecipe(Convert.ToInt32(cbxRecipe.SelectedValue));

            string LastDigit = RecipeName.Substring(4, 1).ToString();
            if (LastDigit == "2") // Has both oils in - allow split
            {
                txtPPATK601.IsReadOnly = false;
            }

        }

  public void PopulateComboBox()
        {
            Managers.BatchMaterialManager.SetAdriotConnection();
            var Recipes = Managers.AdrBatchRecipeManager.GetCboRecipe();

            Recipes.DefaultView.Sort = "idx";
            View.ComboRecipe.ItemsSource = null;
            View.ComboRecipe.ItemsSource = Recipes.DefaultView;

            View.ComboRecipe.DisplayMemberPath = "StockCodes";
            View.ComboRecipe.SelectedValuePath = "idx";
            View.ComboRecipe.SelectedIndex = 1;
        }`

Posted 24-Jun-24 21:22pm

Gcobani Mkontwana

Updated 24-Jun-24 23:23pm

Pete O'Hanlon

v2

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Pete O'Hanlon · Answer 1 · 2024-06-24T23:35:00

You seem to be using a very cumbersome way of managing your combobox here. If I were you, I would be tempted to bind (once) to an extension of the ObservableCollection that manages bulk change notifications for you[^]. Then, when I was loading the data in, I would clear all the records if any were previously loaded, and add in the entirety of the data using AddRange. By doing this, you are bringing your application back into line with what WPF expects, and letting change notifications inform the UI when there are items present.

Also, don't do so much in the code-behind. You can set things like the ItemsSource, DisplayMemberPath, SelectedValuePath, and so on inside the XAML.

Graeme_Grant · Answer 2 · 2024-06-25T00:00:00

Solution 2

This tutorial website will show you a few different ways: The ComboBox control - The complete WPF tutorial[^].

Also, check out the rest of their tutorials.

Posted 25-Jun-24 0:00am

Graeme_Grant