I have a silverlight datagrid control and columns autogenerate property is set to false.
I am using MVVM and wants to bind the columns collection.
The data which i get is from xml. Something similar to sample code
Link
Now by passing the datagrid control from xmal file to the modelview I can get the expected behavior but with that way , i am adding columns in the datagrid control.
Is there any way, so that I can bind the columns collection with the datagrid control so that no need to pass the control to view model.
-Rajesh
Sounds like a strange implementation of MVVM you have there. Your ViewModel should be completely independent of the View. If you want to create dynamic columns on the grid then why not expose a relevant property collection on the ViewModel, and iterate through it in a relevant method on the View code behind e.g.
//Used with an Infragistics XamWebGrid control
private void BuildGrid() {
foreach (var dataItem in **ViewModel**.MyDataCollection)
{
var myCol = new TemplateColumn
{
HeaderText = dataItem.ItemNm,
Key = dataItem.PrimaryKey
};
MyGrid.Columns.Add(myCol);
}
}
You really shouldn't be passing controls from the View over to the ViewModel. The ViewModel should have no knowledge of any controls on the View.
Related
WPF window in C# doesn't have option of Inserting something into DataGrid immediately, like as WinForms Form
DataGridView.Rows.Add(whatever)
What is alternative for this code 👆?
So how can I insert an array into DataGridView in WPF window?
You can actually add objects directly to the Items property of the DataGrid:
dataGrid.Items.Add(whatever);
But if you want to be able to edit the items, you should set or bind the ItemsSource property to an IList:
dataGrid.ItemsSource = new List<object> { whatever };
You need to bind the DataGrid to an ObservableCollection. If you insert into the ObservableCollection, it'll appear on the UI
I have a silverlight datagrid to which I am binding an observable collection from the viewmodel. There is a detail view page which will display different properties of the object in the collection when user selects a row of the datagrid. My requirement is when user updates any properties in the detail view; the data should be updated in the data grid also. How to implement this functionality?
Well, the answer is simply to bind both the datagrid row and the control displaying the selected object. The simplest way is to use a ICollectionView (returned by a CollectionViewSource from the original ObservableCollection), bind the grid's ItemsSource to that, and then bind the control's DataContext to the ICollectionView's CurrentItem. That way, when the grid's selected item changes, the CurrentItem of the ICollectionView is updated, and that item is displayed in the detail view.
I think it's quite easy but if you need additional details or sample source code I'll elaborate.
I have a WPF user control ...which is in MVVM. The user control(which contains a listview) need data from the page (where it is included). I have to set a property to get this data input. Will this comply with MVVM...if not, what is the way for the same?
I'm afraid this won't be correct in MVVM design pattern. try to stick to your view model to define properties. Why don't you consider moving that property to control's vm?
Use an ObservableCollection rather.
ObservableCollection<myModel> myOC = new ObservableCollection<myModel>();
where myModel is a class that has to be constructed transforming your columns in the DataTable to Properties.
In your MainViewModel, loop through the DataReader and create myOC out of it.
Now bind myOC to a ListView in your page.
The DataTemplate of ListView should be a view(UserControl) drawing data from a ViewModel constructed out of myModel
But your UserControl has the entire ListView inside. If that is on purpose, then let me know the entire design to give a better idea.
I have Window that has a ListBox
ListBox(MyListBox) has a DataTable for its DataContext
ListBox's ItemSource is : {Binding}
Listbox has a UserControl(MyUserControl) as DataTemplate
UserControl has RadioButtons and TextBoxes (At first They're filled with values from DataTable and then user can change them)
Window has one Submit Button
What I want to do is, when user clicks the submit button
For each ListBox Item, get the values form UserControl's TextBoxes and RadioButtons.
I was using that method for this job :
foreach(var element in MyListBox.Items)
{
var border = MyListBox.ItemContainerGenerator.ContainerFromItem(element)as FrameworkElement;
MyUserControl currentControl = VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(myBorder,0) as Border,0)as ContentPresenter,0)as MyUserControl;
//And use currentControl
}
I realised nothing when using 3-5 items in Listbox. But when I used much more items, I saw that "var border" gets "null" after some elements looped in foreach function.
I found the reason here :
ListView.ItemContainerGenerator.ContainerFromItem(item) return null after 20 items
So what can I do now? I want to access all items and get their values sitting on user controls.
Thanks
You should use objects who implement INotifyPropertyChanged and bind an ObservableCollection of it to the ItemSource
And then you can get all the list of items.
Here some quick links from MSDN to get more informations
How to: Implement Property Change Notification
Binding Sources Overview
You should google for some tutorials about this.
Zied's post is a solution for this problem. But I did the following for my project:
I realised that there's no need to use UserControl as DataTemplate in my project. So I removed ListBox's DataTemplate.
I removed MyListBox.DataContext = myDataTable and used this:
foreach(DataRow dr in myDataTable.Rows)
{
MyUserControl muc = new MyUserControl(dr);
myListBox.Items.Add(muc);
}
I took DataRow in my UserControl's constructor and did what I want.
And at last I could access my UserControls in ListBox by using :
foreach(MyUserControl muc in
myListBox)
{
//do what you want
}
Easy huh? :)
I am creating a DataForm from dynamic data (so I can't create the columns in the xaml), I currently create columns for my DataGrid (I have not worked out how I can create a button + event in a colomn yet)
foreach (var item in headings.Entities)
{
theDataGrid.Columns.Add(
new DataGridTextColumn
{
Header = item.Label,
Binding = new Binding(item.LocalName)
});
}
I cannot see any methods to add fields to a DataForm at runtime, however...
You'd be better off not creating your datagrid columns in code, but using bindings instead. Just bind the datagrid to the headings.Entities collection.
The same thing with your DataForm, just bind your item to it and it should create all the proper fields for you.