Can you tell me what event fires when individual textboxes that are bound to a data source using the properties pane gets refreshed?
I wish to use this event to populate a few textboxes that are not bound.
It depends on what property control is bound, usually textboxes are bound on Text property, so your "event" is TextChanged event
Related
What is the best way to deal with a combo box event? In other words, what is the best event handler to use for the case that the user makes a selection from the combo box? I am using a textchanged event, but it seems a bit sloppy. Is there a better way? By the way, my program that I am using it for is a unit converter that converts length.
The textchanged event fires whenever the text inside the combobox changes. every character added to the combobox triggers it, which makes it sloppy.
To avoid performance issues, use either Lostfocus (which fires if the control isn't selected anymore) or the SelectedValue /Selectedindex changed events.
To answer your other question, manipulate the keypress event.
Go to the combobox's keypress event, and type this:
e.handled = true
this will reject any input from user.
I have a combobox on a winform, and need to be able to call a method when the combobox's databinding is complete. I am surprised to see that there is no DataBindingComplete event for the ComboBox control, like there is for the DataGridView.
How can I know when data binding is complete? Is databinding done synchronously for comboboxes? (i.e., if I have the following code, is it guaranteed that data binding will be complete when it hits the second line of code?)
myComboBox.DataSource = foo
SomeMethod()
You could make a class where you handle all the data access, then as the data is retrieved you can raise an event from that layer to the calling form you use to display your data.
Data Access Layer
Have a situation where i need to suppress the SelectionChanged event logic until the DataGridView has completed Binding operations.
I have tried setting a Boolean flag variable to denote binding operations but it basically triggers the DataBindingComplete after each row is added.
Is there a way i can design a Dirty flag for the whole control that way the SelectionChanged event isnt triggered until the full DataSource has been bound to the DataGridView?
I have a combobox where the SelectedValue on the combo is bound to a property on a business object.
Everything works fine, but the property that's bound to the SelectedValue on the combo only gets updated when the focus leaves the control. I understand that the property doesn't get updated until the control is validated (loses focus), but I need it to update the datasource as soon as the dropdown is closed.
I know I could probably leave focus from the control on the DropDownClosed event but I'd prefer something a little less kludgy.
What's the best way to immediately update my datasource when the dropdown is closed?
Set the DataSourceUpdateMode to OnPropertyChanged. Here is similar problem:
[http://social.msdn.microsoft.com/Forums/en/winformsdatacontrols/thread/bc39342b-d9b5-4ad0-bd35-073869ccf8be][1]
The way I'd do it is to set (in the events) the OnUpdate of the combo box and put in the VB.net
Me.<business object>.Requery
I have a ComboBox bound to a table field and I want to validate the selection, since only certain selections are valid depending on context. When in the On Validating Event how can I get the Value before or what it is in the table.field before selection changed?
The WinForms ComboBox control doesn't provide the functionality of being able to intercept a value change and cancel it. You can use the Validating event (or, as you describe, subclass the ComboBox and override OnValidating), but these only allow you to keep the focus on the control. You can't actually "cancel" a value change through the validating events.
There are several third-party (DevExpress, for example) packages that provide ComboBoxes that allow you to inspect both the initial and the new values when the value changes and cancel the change if desired, but the ComboBox provided in System.Windows.Forms does not.