I have a problem with System.Window.Forms.CheckBox databinding. I generate a checkbox and then map it's value to a property on a BindingSource via
Checkbox → Properties → DataBindings → Checked → BindingSource - PropertyValue
I then have a CheckedChanged event that get's triggered when i click on the checkbox. However on click the BindingSource property is not updated. Because of this I have to use checkbox Design -> Name to get the value of the checkbox. Should the binding be done in another way? I can map strings this way with no problem but for some reason a checkbox bool seems harder to map.
When you setup data-binding, the default value for Data Source Update Mode is OnValidation which means Data source is updated when the control property is validated. So in the current state if you move the focus to another control the data-binding will update the data source property.
If you want data source update whenever the value of the control property changes, you should change the setting to OnPropertyChanged.
You can change the setting using designer this way:
Select the control and in property grid, expand (DataBindings) and click ... in from of (Advanced) to open Formatting and Advanced Binding.
In the window, from the left Property list, select the property which you want to perform advanced setting for it.
At right pane, from Data Source Update Mode select OnPropertyChanged. To learn more about other available values, take a look at DataSourceUpdateMode documentations.
Related
I have a TabControl, and each TabItem has multiple, data-bound textboxes. When I edit an text in one box, and the switch the tab directly (without leaving the textbox), the change is lost. Apparently, the "LostFocus" Event is not triggered when changing the tab, so the new value is not written to the bound property.
How can I trigger the "LostFocus" on the currently active (or all) elements in the active tab before changing over to the new tab?
I could surely do an override and call the event manually on all elements, but that would be quite unhandy because one has to update that list every time a field is added.
Is there some way to do it automatically?
Use UpdateSourceTrigger.PropertyChanged instead of LostFocus and set the binding Delay property to an interval of your choice.
A while back i had read a tutorial on data binding (maybe it was MVVM?) in Windows Forms. I've sense forgot everything and forgot the name of the tutorial.
What i would like to do is bind the enabled property of a button to a combox's selected item.
Logic: If combobox has selected item- enable button.
else disable button.
I'm aware of the combobox_textchanged and combobox_selecteditemchanged event and i would like to avoid using it if possible.
In WPF / MVVM, this is a UI issue that can be handled in a ViewModel class. In Windows Forms, you might also want to create a ViewModel class separate from your model class to keep UI concerns away from the Model classes. Either way, you can create a Boolean property like "IsActiveCustomer", or whatever it is in your case, in the object class you are binding to. Your property could either have a getter that returns a value based on the property that is bound to the combo box -- or you could use the combo box selected index changed or selected value changed events and set the Boolean property accordingly. Then, of course, bind the Enabled property of the button to the Boolean property. Probably need to know what you are data binding to in order to provide specifics (binding to object vs. BindingSource/table adapter, etc.)
There is a WPF DataGrid with columns that have checkboxes. These checkboxes are already bound to some data source. What we want is a checkbox for each column that checks/unchecks all the checkboxes (and as a result updates the data source so that all the values are the same).
Existing solutions on here work if there isn't an existing datasource - but we have effectively two, the 'select all' checkboxes and the actual data that the other checkboxes in the rows are bound to, if that makes sense.
If we could use a trigger or somesuch instead of 'code behind' that would be ideal. Is there a declarative solution?
Make your CheckBox's Click event point to a Command in your ViewModel that iterates your DataSource and sets IsChecked to true.
The standard solutions can work with a databound grid. An example is found (http://www.4guysfromrolla.com/articles/120810-1.aspx). This example if fully client side.
The problem comes when you postback, but that is only a problem if you are not persisting the check all back to the database and refreshing the data you are binding. In those cases, you need to ensure something is passed back to indicate the check all so you can dynamically set the boxes again after a postback.
Is there a property or setting to force a bound control in Winforms to update the object it is bound to when the input value, either in a textbox or whatever, actually changes?
And not after the control is tabbed out of.
Assuming you have already bound the textbox to something:
Select the textbox in the designer
Click property "databindings"
Click property "advanced"
In this dialog look for the "datasource update mode"
Select onpropery changed instead of onvalidate
Now the datasource gets updated on every change of the text property of the textbox.
I want to enable or disable the toolstripitems on the bindingnavigator programmatically.
When I try to set the toolStripitem's enable property, it does not change. It does not give any exception but the value of Enable property does not change.
What did I miss?
The BindingNavigator takes control of these buttons itself, to enable/disable them as appropriate; i.e. you can't go prev/next if there is no more data, you can't add/delete without the underlying source letting you (IBindingList.AllowNew/.AllowRemove.
Which buttons do you want to tweak? For example, you can disable add/remove by using a data-source such as BindingList<T>, and setting AllowNew=false/AllowRemove=false.
Alternatively, simply write your own buttons completely (forget BindingNavigator) - it isn't a lot of work, especially if you start with a BindingSource on the form (since that has all the necessary MoveFirst() etc.