I am using MVVM for my WPF application. I have a AutoCompleteBox in my xaml file which works normally. But now, I added a bool flag in my ViewModel isHideDropDown which will hide dropdown for the AutoCompleteBox if set to true. To summarise, I want my AutoCompleteBox to work as normal TextBox if isHideDropDown is set to true.
Can anyone give me some idea?
Thanks
Assuming you're using the AutoCompleteBox described here.
Setting the MinimumPrefixLength to -1 will disable the auto complete functionality of the control.
So, if you add an int MinimumPrefixLength property to your ViewModel that returns -1 when isHideDropDown is true, then you can bind to that. The other option would be to write a value converter that converts the boolean isHideDropDown value to the appropriate integer.
I have't tried this. But, instead of setting isHideDropDown to true, why not set the object that binds to ItemSource property as null?
In an autocompleteBox you need to set the ItemSource. When you don't want the autocomplete feature just set that object to null
You can also try to override ItemContainerStyle:
http://msdn.microsoft.com/en-us/library/dd795156%28v=vs.95%29.aspx#customizing_the_appearance_of_the_autocompletebox
Use DataTrigger with Binding to conditionally set ItemContainer's Visibility to Visible/Collapsed
Related
I have a series of WrapPanels within a DockPanel. I want all but the top panel to be disabled at the beginning but all panels to be visible. As the user satisfies conditions in one panel I want to enable another panel. However, I can't figure out how I can bind the IsEnabled property of the WrapPanel (or if I need to the individual elements) to a boolean in my ViewModel. Any idea?
Update2: This works amazingingly! Adding a convention for IsEnabled to Caliburn.Micro
Update: Oops I lied. It keeps resetting all of my XAML by having an object of the same type in the ViewModel.
Just realized that I can just create an instance of what I am trying to >enable/disable in the ViewModel and from that access the IsEnabled property. Not >direct but works!
In my WPF application, my Viewmodel has a boolean property IsOwnerOf and a string property Title. If IsOwner==false, I want a TextBlock displaying the Title (because if you're not the owner, you should not be able to edit it) and if IsOwner==true, I want a TextBox displaying Title - obviously at the same place in the view.
Also I don't want to do it codebehind since I follow the MVVM pattern. Thought about Style.Triggers, but with them I can only influence attributes of an element, not the element type itself, or can I?
EDIT:
Practically the answers below regarding triggering Visibility or IsReadOnly work, but I still would like to see a conceptually better answer! What if I replace the TextBox resp. TextBlock by elements that don't have these convenient properties? There must be a better way than creating both and hiding one of them, that just doesn't sound right...
The easiest option is to always drop a TextBox and bind it's IsEnabled or IsReadOnly property to the IsOwner flag.
You can also use a DataTemplateSelector to achieve this.
You can use triggers to change the Visibility of your TextBlock and TextBox using a BooleanToVisibilityConverter
I have a listbox bound to a List<object> as its DataSource. What I'm wanting to do is use the SelectedValue property of the Listbox (i.e the object corresponding to the current selection) as a DataSource for some textboxes that will display certain values of the object for editing.
I've tried
TextBox.DataBindings.Add(new Binding("Text", ListBox, "SelectedValue.name"));
and
TextBox.DataBindings.Add(new Binding("Text", ListBox.SelectedValue, "name"));
but as there is nothing selected in the ListBox (because the form hasn't been shown yet), I get an exception about "Value cannot be null".
Now I know that I can (re)bind to ListBox.SelectedValue in my form's SelectionChangeCommitted handler (that is, after a selection has been made), but if i have to do that I might as well just set the TextBox's value directly (admittedly I could just do this to resolve the issue, but I'd like to learn more about databinding).
So my question is, in short: Is it possible to bind to ListBox.SelectedValue once (initially, before the ListBox has a selection) and avoid the null value exception, and if so, how?
I'm not sure which control your projectNameCtrl is, but you'll want to bind your TextBox. Something like this:
textBox1.DataBindings.Add(new Binding("Text", listBox1, "selectedvalue"));
Where:
textBox1 is your TextBox
listBox1 is your ListView
EDIT
You should be able to data bind a ListBox even if that ListBox has no selected items so your 'value cannot be null' must be for another reason. I suggest using the debugger to determine which object specifically is null.
You can ensure you don't data bind a control more than once by first checking the control's DataBindings.Count property; if it's equal to zero you haven't yet data bound that control:
if (textBox1.DataBindings.Count == 0) {
// OK to data bind textBox1.
}
Off the top of my head, I think you'd need to do something on each selectedItemChanged event...
I know this doesn't answer your question, but I'd look at using WPF instead since this is so much more elegant to do in WPF, and let's face it, by not creating a GUI in code (using XAML instead) your sanity will be much more intact when you finish your project. I don't recall enough windows forms, but in WPF, you just implement INotifyPropertyChanged on your back-end object that you're binding to, and then when you bind to the SelectedItem property of that ListBox, you automatically get updates since the SelectedItem property is a DependencyProperty.
I have an ItemsControl object and am setting the DataTemplate to hold a Grid with a couple controls in it. The controls are databoud to a collection of some object MyObj, specifically a TextBlock and a ComboBox. MyObj has its own collection inside of it for a property. If that property has only 1 object in its collection, only the TextBlock is visible. But if there is more than 1 object in the collection, the TextBlock is visible and the ComboBox becomes visible once the TextBlock is clicked on.
I have the ComboBox filled up with what it needs, I just can't figure out how to specify which ComboBox needs to become visible when the TextBlock is Clicked on.
I guess my question is, how would I even go about doing this? Or, is there a better way to think about this problem?
I'm new to databinding in Silverlight and running into a bunch of issues on my own. Any help is always appreciated. Thank in advance.
One thing that you could do is add an extra property to the data item that you binding to, something like 'IsSelectionAvailable'. Make the visibility of your combobox bound to this property (via a boolean to Visibility enum Value Converter). Finally, add a click event handler for the text box that sets the IsSelectionAvailable property to true for the object it is bound to.
Hope that helps.
Basically I have some CheckBox controls I want to use to show or hide certain GridViewColumns at runtime. But I failed to find a sort of IsVisible property that I can set to false. Or even a Visibility property that exist only on GridViewColumnHeader.
Any ideas on how to do this?
Set the GridViewColumn Width property to 0. This will achieve the same effect as hiding it. This can be achieved with DataBinding and a Converter.