I have a simple datastructure following:
In the model I have
public class Receipt
{
public int Id { get; set; }
public double Price { get; set; }
public string Store { get; set; }
public DateTime Date { get; set; }
}
I've made two of these objects and I am trying to bind them to a datagrid. I've filled in the properties of the two receipts and added them to the dataGridRows but they don't show up in my DataGrid.
public MainWindow()
{
InitializeComponent();
makeReceipts()
}
public ObservableCollection<Receipt> dataGridRows = new ObservableCollection<Receipt>();
public Receipt receipt1 = new Receipt();
public Receipt receipt2 = new Receipt();
public void makeReceipts()
{
receipt1.Id = 1;
receipt1.Price = 10;
receipt1.Store = "Brugsen";
receipt1.Date = DateTime.Today;
receipt2.Id = 2;
receipt2.Price = 15;
receipt2.Store = "Netto";
receipt2.Date = DateTime.Today;
dataGridRows.Add(receipt1);
dataGridRows.Add(receipt2);
}
And in the xaml of the MainWindow where I want my datagrid to display the receipts I have:
<DataGrid Name="ReceiptGrid" CanUserResizeColumns="True" IsReadOnly="True" AutoGenerateColumns="True" ItemsSource="{Binding Source=dataGridRows}" />
What am I doing wrong?
first you can just bind to public properties.
so if you want to use binding you have at least do:
public ObservableCollection<Receipt> dataGridRows {get;set;}
second you have to do two steps:
set the right datacontext
set the right binding expression(Path)
assume that the datacontext for yyour grid is an object with the property dataGridRows, your binding should look like this
<DataGrid ItemsSource="{Binding Path=dataGridRows}" .../>
Think your problem is you have to write
ItemsSource="{Binding Path=dataGridRows}"
and not
ItemsSource="{Binding Source=dataGridRows}"
source is to specify another control in xaml file
First of all you can bind only public properites so you need to change definition of dataGridRows to something like this:
public ObservableCollection<Receipt> dataGridRows { get; set; }
then you don't bind it as a Source but as a Path, however since your dataGridRows is defined in MainWindow you need to specify Source as your MainWindow otherwise it will look in default DataContext which is not set in your case
<DataGrid ... ItemsSource="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}, Path=dataGridRows}" />
this tells Binding to find Window and look for a dataGridRows property there.EDIT:Normally you don't put data into view. I suggest you read more about MVVM design pattern but basically the idea is that you have your ViewModel where you put in you whole application logic, unaware of interface, and then on top you have your view to interact with user but in ViewModel you don't operate on controls.What you should do is create your view-model class with dataGridRows property and assign it through DataContext of Window for example. Each FrameworkElement has it and when you don't specify Binging source (Source, RelativeSource, ElementName) it will try to resolve Binding.Path in current DataContext. If current control does not have it specified then if will go to parent in visual tree and so on.
Related
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Creating and binding buttons dynamically in a WrapPanel
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I am trying to set ItemSource property for listview without success.
View (xaml):
<ListView Margin="10" Name="MyLv" ItemsSource="{Binding}">
....
</ListView>
Code-Behind Constructor (xaml.cs):
public MyView()
{
InitializeComponent();
}
ViewModel:
private List<DataModel> lstData = null;
public MyViewModel()
{
this.lstData = this.LoadData(); // this connects to a database an extract info to be loaded in listview
}
Data Model:
public class DataModel
{
public bool IsSelected { get; set; }
public string ID { get; set; }
public string Desc { get; set; }
}
Before this, I was loading the listview from code-behind and it was working, but now I want to load it from my viewmodel and I do not know how can I make it work.
Based on the code you posted, there are a couple of problems:
You haven't set the DataContext of the view. You typically want to set this to an instance of your view model class.
The ViewModel doesn't expose the list as a public property. WPF bindings only work on public properties. The ItemsSource should be bound to this property, and not to the DataContext itself.
Finally, you probably want the collection in the ViewModel to be an ObservableCollection. This way, when changes are made to the collection, the list in the UI will be automatically updated.
I've got a ComboBox (inside a ListView) that used to be tied to a collection of strings. However, I'm switching to having it use a custom class instead.
Now the ComboBox is bound to an ObservableCollection of type Area. For display, I'm showing the Name property with DisplayMemberPath. This works great, but the box is no longer loading with the current value selected.
<ListView x:Name="TestListView" ItemsSource="{Binding TestViewList, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
<ListView.View>
<GridView>
<GridViewColumn Header="Area">
<GridViewColumn.CellTemplate>
<DataTemplate>
<ComboBox ItemsSource="{Binding DataContext.AreaList, ElementName=BVTWindow}" DisplayMemberPath="Name" SelectedItem="{Binding Path=Area, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}" />
public ObservableCollection<ViewTest> TestViewList { get; private set; }
public ObservableCollection<Area> AreaList { get; private set; }
public class ViewTest : BindableBase
{
public string Description { get; set; }
public Area Area { get; set; }
}
public partial class Area
{
public long ID { get; set; }
public string Name { get; set; }
}
"Area" is the same class as the Collection, and is a property of the class the ListView's ItemsSource is bound to. Am I doing this the right way? Any help is much appreciated.
UPDATE:
I had a theory that perhaps using the "Name" property (which is a string) for display in the box made the SelectedItem attribute look for a string rather than something of type Area. I changed the class for TestViewList to use a string to keep track of Area, but that didn't change the program's behavior at all.
UPDATE 2:
Above, I've added the pertinent lines from the view model related to the ComboBox and ListView in question.
Update 3:
I've changed my Area property from inline to expanded, including the SetProperty that handles raising. It now works for new items added to the ItemSource at run-time, but is still a blank selection for on items loaded at program start.
public class ViewTest : BindableBase
{
public string Description { get; set; }
public Area Area
{
get
{
return this.area;
}
set
{
this.SetProperty(ref this.area, value);
}
}
}
Update 4:
It turns out Paul Gibson's answer was correct. The reason my existing entries weren't loading properly had to do with a logic error in the way I was loading items from the database, and not a problem with the xaml bindings. Everything works now (with respect to those ComboBoxes, at least).
Based on what you are saying I think my comment is the answer. This is the case for a single combobox. In your case you need one for every line of the grid, so you may have to programatically add the binding to members of a list by index.
In your view model if you also have (single case):
private Area _curSelArea;
public Area curSelArea
{
get { return _curSelArea; }
set
{
_curSelArea = value;
RaisePropertyChanged("curSelArea");
}
}
Then you can bind to the property with:
SelectedItem="{Binding DataContext.curSelArea . . . }"
The view model can set the initial value of curSelArea if it is known initially.
EDIT: After actually having to do this I found that someone extended the DataGridComboBoxColumn to facilitate better binding. Check out this link if you are trying to do this: http://joemorrison.org/blog/2009/02/17/excedrin-headache-35401281-using-combo-boxes-with-the-wpf-datagrid/
I have a window with 3 textboxes in a grid -this is my view- and I have Save button to add a new user to my user list with the datas from the textboxes.
I want to use a relay command to do this on my viewmodel class but I am quite confused with how to make the bindings. I hope it's clear enough. Any ideas, or examples will be helpful.
thanks in advance.
You should have a ViewModel something like the following :
class UserViewModel
{
public String Name { get; set; }
public String Password { get; set; }
public String Email { get; set; }
public RelayCommand AddUserCommand { get; set; }
public UserViewModel()
{
AddUserCommand = new RelayCommand(AddUser);
}
void AddUser(object parameter)
{
// Code to add user here.
}
}
And you can use it like following :
<StackPanel>
<TextBox Text="{Binding Name}"></TextBox>
<TextBox Text="{Binding Password}"></TextBox>
<TextBox Text="{Binding Email}"></TextBox>
<Button Command="{Binding AddUserCommand}">Add</Button>
</StackPanel>
To make this work, put following code in your UserControl/Control/Window's constructor :
DataContext = new UserViewModel();
I presume that you read Josh Smith article: WPF Apps With The Model-View-ViewModel Design Pattern. If you didn't, then read it first, and then download code, because example is very similar to your problem.
Did you created an instance of the ViewModel and putted this instance in the DataContext of your view or stackpanel?
example:
UserViewModel viewModel = new UserViewModel();
UserWindow view = new UserWindow();
view.DataContext = viewModel;
view.Show();
There are several options on coupling the View and the Viewmodel:
Create the View and ViewModel and set the ViewModel to the DataContext property (code above)
Create the ViewModel in the constructor of the View and fill the DataContext property with it
Create a Resource in your view of the type of your ViewModel and fill the DataContext property in XAML
I prefer the first option because you can combine the Views and Viewmodels as you like at runtime.
Hopefully this is a helpfull answer.
I have a simple ViewModel like:
public class MainViewModel {
ObservableCollection<Project> _projects;
public MainViewModel() {
// Fill _projects from DB here...
ProjectList.Source = _projects;
ProjectList.Filter = ...;
}
public CollectionViewSource ProjectList { get; set; }
}
I set the window's DataContext to a new instance of that ViewModel in the constructor:
public MainWindow() {
this.DataContext = new MainViewModel();
}
Then in the Xaml I am attempting to bind the ItemsSource of a ListBox to that ProjectList property.
Binding just ItemsSource like so doesn't work:
<ListBox ItemsSource="{Binding ProjectList}" ItemTemplate="..." />
But if I first rebase the DataContext this works:
<ListBox DataContext="{Binding ProjectList}" ItemsSource="{Binding}" ItemTemplate="..." />
Shouldn't the first method work properly? What might I be doing wrong?
If you are using CollectionViewSource you need to bind ItemsSource to ProjectList.View instead of ProjectList. That should solve your problem.
From what you provided the first method should perfectly work. Devil lurks somewhere in details.
PS: Maybe you didn't specify implementation of INotifyPropertyChanged interface in sake of post size, but be careful in production. It's very easy to get a memory leak if you don't implement it.
I have next enumeration
Enum rcCategory
{
Incoming,
Internal,
Outgoing
}
and I have property "categories" in my class which has rcCategory[] type.
I would like to bind this property to the listBox. I use next code for this
MyListBox.SetBinding (ListBox.ItemsSource, new Binding {Source= myClass.categories});
But this code doesnt work as expected.
How Can I do this. My listBox always is empty but source property has value
See Bea Stollnitz top ranked article on it.
In short you need to bind to an ObjectProvider which calls the static method Enum.GetValues( typeof(YourEnum) ) to return the list.
http://bea.stollnitz.com/blog/?p=28
Update: Sorry got a slight speedreading issue. This one is easier.. Verified that it works. Recommended: Find up a copy of ProgrammingWPF and go thru the DataBinding chapter...
XAML:
<ListBox DockPanel.Dock="Left" ItemsSource="{Binding EnumArrayProp}"/>
Codebehind:
public partial class Window1 : Window
{
public rcCategory[] EnumArrayProp
{
get; set;
}
public Window1()
{
InitializeComponent();
this.EnumArrayProp = new rcCategory[] { rcCategory.Incoming, rcCategory.Incoming, rcCategory.Outgoing };
this.DataContext = this;
}