Loop through combobox items to get value

Question

0.00/5 (No votes)

See more:

.NET4.5

I have a Session table. Within the Session table I have a field - SessionTypeID - that references the SessionType table (foreign key). I have a combobox that I have created with SessionTypeName entries from the SessionType file. When a Session is selected I want to match the SessionTypeID from the Session file, with the entries in the SessionType combobox, and make that the selected (default) index. I assumed I would iterate through the combobox items and find the matching entry, but it's proving more difficult than I anticipated. I'm using WPF, C# and .NET 4.6 All the examples I've found don't seem to work with 4.6.

For example:

C#

for (int i = 0; i < comboBoxSessionDataSessionType.Items.Count; ++i)
{
    MessageBox.Show(comboBoxSessionDataSessionType.Items[i].ToString());
}

shows the following: 'Systems.Windows.Controls.ComboBoxItem: 120 Film'
'120 Film' is the value I'm looking for.

Any ideas on how to accomplish this?

Here is the code for getting the Session table data:

C#

string sql = @"SELECT * FROM Session WHERE SessionID = '" + id + "'";
           //  MessageBox.Show(sql);
           SQLiteCommand com = new SQLiteCommand(sql, conn);
           System.Data.DataSet ds = new System.Data.DataSet();
           SQLiteDataAdapter ad = new SQLiteDataAdapter(sql, conn);
           ad.Fill(ds);
           GridSessionData.DataContext = ds.Tables[0].DefaultView;

Here is the button XAML code:

XML

<combobox x:name="comboBoxSessionDataSessionType" grid.column="1" grid.row="2" style="{DynamicResource ComboboxData}" itemssource="{Binding Path=SessionTypeID, Mode=TwoWay}" datacontext="{Binding SessionTypeName}" selecteditem="{Binding Path=SessionTypeID}" selectedvalue="{Binding Path=SessionTypeID}" tag="{Binding Path=SessionTypeID, Mode=TwoWay}" xmlns:x="#unknown" />

C#

string sql = @"SELECT * FROM Session WHERE SessionID = '" + id + "'";
           //  MessageBox.Show(sql);
           SQLiteCommand com = new SQLiteCommand(sql, conn);
           System.Data.DataSet ds = new System.Data.DataSet();
           SQLiteDataAdapter ad = new SQLiteDataAdapter(sql, conn);
           ad.Fill(ds);
           GridSessionData.DataContext = ds.Tables[0].DefaultView;

Here is the button XAML code:

<combobox x:name="comboBoxSessionDataSessionType" grid.column="1" grid.row="2" style="{DynamicResource ComboboxData}" itemssource="{Binding Path=SessionTypeID, Mode=TwoWay}" datacontext="{Binding SessionTypeName}" selecteditem="{Binding Path=SessionTypeID}" selectedvalue="{Binding Path=SessionTypeID}" tag="{Binding Path=SessionTypeID, Mode=TwoWay}" xmlns:x="#unknown">

Mika, here is how I filled the combobox:

C#

 string sql = @"SELECT SessionTypeID, SessionTypeName FROM SessionType WHERE Active = 1 ORDER BY SessionTypeName";
          
            SQLiteCommand com = new SQLiteCommand(sql, conn);
            System.Data.DataSet ds = new System.Data.DataSet();
            SQLiteDataReader dr = com.ExecuteReader();
            List<ComboBoxItem> list = new List<ComboBoxItem>();
            while (dr.Read())
            {
                ComboBoxItem item = new ComboBoxItem();
                item.Content = dr.GetValue(1).ToString();
                item.Tag = dr.GetValue(0).ToString();
                list.Add(item);
                }

            // add/edit selection
            ComboBoxItem itm = new ComboBoxItem();
            itm.Content = eesConstants.EESADDEDIT;
            itm.Tag = "";
            list.Add(itm);

            //  comboBoxSessionDataSessionType.Items.Add

(eesConstants.EESADDEDIT);
            comboBoxSessionDataSessionType.ItemsSource = list;

When I retrieve the Session entry, I know what the SessionTypeID is:

C#

ds.Tables[0].Rows[0]["SessionTypeID"].ToString()

Now that I have the SessionTypeID, how do I match it up with the correct entry in the SessionType combobox?

The combobox ItemSource is connected to the dataset where I'm getting the Session Data from:

XML

<ComboBox x:Name="comboBoxSessionDataSessionType" Grid.Column="1" Grid.Row="2" Style="{DynamicResource ComboboxData}" ItemsSource="{Binding Path=SessionTypeID, Mode=TwoWay

Posted 28-Sep-15 9:39am

Robert Kamarowski

Updated 29-Sep-15 4:16am

v6

Add a Solution

Comments

Richard Deeming 29-Sep-15 9:40am

Your code is vulnerable to SQL Injection[^].

NEVER use string concatenation to build a SQL query. ALWAYS use a parameterized query.

2 solutions

Solution 1

You don't need to loop through the collection. Have a look here: http://www.dotnetperls.com/combobox-wpf[^]

Posted 28-Sep-15 9:57am

Maciej Los

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Wendelius · Accepted Answer · 2015-09-28T10:32:00

When you loop through the items in a combo box you actually loop through the objects assigned to the combobox using the ItemsSource property. For example if the items source is a data view your loop would iterate through the datarow objects from the view. So when you call the ToString method it's called on the whole object.

Now in order to set the correct selected item in the combo box you have two options, use the index which is a more 'traditional' way but can be more difficult or you can also select the correct object from the data source and assign it into SelectedItem.

For example if you think about the dataview example, you can take any of the data rows from the view and assign that row into SelectedItem. You don't need to fetch the data row from the combo box at all, you can query the dataciew, loop through it, or what ever is the best way to find the correct object. This is one really big difference compared to for example Windows Forms.

You didn't post info how you actually fill the combo box but try setting the any of the actual objects in the ItemsSource to the SelectedItem and you'll see how it works.

ADDITION:

An example to select an item in the second combobox based on a data row value selected in the first combo box.

XAML

XML

<Window x:Class="CPWPF_C.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" 
        Height="350" 
        Width="525">
    <Grid >
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <ComboBox Grid.Column="0" Grid.Row="0" Name="FirstBox" DisplayMemberPath="FirstName" />
        <ComboBox Grid.Column="1" Grid.Row="0" Name="SecondBox" DisplayMemberPath="LastName" />
    </Grid>
</Window>

Code

C#

namespace CPWPF_C {
   /// <summary>
   /// Interaction logic for MainWindow.xaml
   /// </summary>
   public partial class MainWindow : Window {
      DataSet _dataSet = new DataSet();

      public MainWindow() {
         DataTable dataTable;

         InitializeComponent();

         // First table
         dataTable = new DataTable("First");
         
         dataTable.Columns.Add("Id", typeof(int));
         dataTable.Columns.Add("FirstName", typeof(string));

         dataTable.Rows.Add(1, "John");
         dataTable.Rows.Add(2, "Jane");
         dataTable.Rows.Add(3, "Someone");
         dataTable.Rows.Add(4, "Another");

         this._dataSet.Tables.Add(dataTable);

         // Second table
         dataTable = new DataTable("Second");

         dataTable.Columns.Add("Id", typeof(int));
         dataTable.Columns.Add("LastName", typeof(string));

         dataTable.Rows.Add(1, "Doe");
         dataTable.Rows.Add(2, "Doe");
         dataTable.Rows.Add(3, "Else");
         dataTable.Rows.Add(4, "Person");

         this._dataSet.Tables.Add(dataTable);

         // define item sources
         this.FirstBox.ItemsSource = this._dataSet.Tables["First"].DefaultView;
         this.SecondBox.ItemsSource = this._dataSet.Tables["Second"].DefaultView;

         // Wire the event
         this.FirstBox.SelectionChanged += FirstBox_SelectionChanged;
      }

      void FirstBox_SelectionChanged(object sender, SelectionChangedEventArgs e) {
         DataRowView dr = (DataRowView)e.AddedItems[0];
         int theRow;

         this._dataSet.Tables["Second"].DefaultView.Sort = "Id";
         theRow = this._dataSet.Tables["Second"].DefaultView.Find(dr["Id"]);
         this.SecondBox.SelectedItem = this._dataSet.Tables["Second"].DefaultView[theRow];
      }
   }
}