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Download the Solution Example: Solution file: ComboBoxFromTable.dbsln |
- Solution Name: Combo Box From Table
- Software Version: v10
- Keywords: Displays. ComboBox. Datasets.
Summary
This solution demonstrates how to populate ComboBoxes using a data table.
Technical Information
First, you need to obtain control of the ComboBox on the display. This is achieved through the following lines:
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ComboBox cbxListCodes;
public void DisplayOpening()
{
cbxListCodes = CurrentDisplay.GetControl("cbxListCodes") as ComboBox;
}
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After that, you need to load your data table. In this example, we will retrieve the entire table asynchronously.
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// Selects the whole table @Dataset.Table.Products.WhereCondition = ""; DataTable dt = await @Dataset.Table.Products.SelectCommandAsync(); |
Next, you can use a simple foreach loop to select which rows to add to the ComboBox, as shown in the code snippet below.
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// Inserts each row to the combobox
foreach (DataRow row in dt.Rows)
{
cbxListCodes.Items.Add(row["ListCode"]);
}
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Now, using an EventHandler, you can determine the value selected by the client from the ComboBox and update the other TextBoxes accordingly but this time, we'll use a different method to also retrieve the status of the SelectCommand, enabling easier troubleshooting if any issues occur. To achieve this, we'll create a new variable, "status," which will be passed by reference. This way, we'll change the SelectCommand method to SelectCommandWithStatusAsync.
Finally, we retrieve the status value using a tag, allowing us to monitor the status directly in the property watch.
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cbxListCodes.SelectionChanged += new SelectionChangedEventHandler(codeChanged);
public void codeChanged(object sender, SelectionChangedEventArgs args)
{
if(cbxListCodes.SelectedValue == null)
return;
// Selecting from the DB only the Item corresponding to the Code Selected in the ComboBox
// Due to dealing with async methods that can't have multiple outputs
// it's used a workaround by passing a reference to an int.
// Therefore, we use this reference to be an input for our SelectCommandWithStatusAsync() method
// and retrieve its value by getting the Value property.
TRef<int> status = new TRef<int>();
@Dataset.Table.Products.WhereCondition = "ListCode = " + cbxListCodes.SelectedValue.ToString();
if(@Dataset.Table.Products.SelectCommandWithStatusAsync(status);
.IsCompleted)
{
@Tag.Status = status.Value;
}
} |
Reference Information
→ See Displays (Desktop and Web) for more information.
→ See ComboBox Control for more information.
→ See Datasets Tables for more information.
In this section:
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