I have two datagrids in a single view but the collections which are ItemsSource of these datagrids are in different View Models. So is it possible to bind these two datagrids with the collections in two different View Models?
Go for a view model combining both:
public class ViewModelA {
public ObservableCollection<CustomClass> Items { get; set; }
/* properties, etc. */
}
public class ViewModelB {
/* properties, etc. */
}
public class CombiningViewModel {
public ViewModelA A { get; set; }
public ViewModelB B { get; set; }
}
Binding can be done like
<DataGrid ItemsSource="{Binding A.Items}">
<!-- Sample, not complete -->
</DataGrid>
No, not directly. You do have options though:
You could set the DataCOntext of the view to itself, then expose each viewmodel through a separate property and bind to those properties:
public class MyView : Window
{
public MyView()
{
this.DataContext = this;
}
public ViewModel1 FirstViewModel { get; set; }
public ViewModel2 SecondViewModel { get; set; }
}
Or you could make a wrapper viewmodel which either extends (inherits from) one of the viewmodels, or wraps them both and surfaces the appropriate properties:
public class MyCompositeViewModel
{
public ViewModel1 FirstViewModel { get; set; }
public ViewModel2 SecondViewModel { get; set; }
}
You can set the DataContext for each DataGrid rather than for the container view.
<Grid>
<DataGrid ... DataContext="..." />
<DataGrid ... DataContext="..." />
</Grid>
Or don't use a DataContext and Bind to the models directly
<DataGrid ItemsSource="{Binding Source={StaticResource ...}}" />
Related
I use MVVM pattern in my WPF application.
I have ObservableCollection Records in my ViewModel.
public enum RecordState
{
NotChanged,
Changed,
Added,
Deleted,
AlreadyExist
}
public class Record
{
public string FirstId { get; set; }
public RecordState State { get; set; }
public string CurrentId
{
get { return GetIdFromInstance(Instance); }
}
public MyStronglyTypedClass Instance { get; set; }
}
public class MyViewModel
{
public ObservableCollection<Record> Records;
// other code
}
In View i have DataGrid.
<DataGrid ItemsSource="{Binding }" //>
What i have to write(if that possible) in ItemsSource="{Binding /* here */}", so that Datagrid Items changed to
Records[0].Instance
Records[1].Instance
Records[2].Instance
...
Records[Records.Count-1].Instance
{Binding} means that your ItemsSource is the DataContext of that DataGrid(probably inherited from ancestor elements).
What you should do is set the DataContext of your top-level element(Window, UserControl etc..) to your ViewModel class.
And then as Gary suggested:
<DataGrid ItemsSource="{Binding Records}">
The link you gave about dynamic elements does the same in that matter, it adds more complicated element bindings and DataTemplates.
I have a wpf combobox bound to a property LogicalP of a class SInstance. The ItemSource for the combobox is a dictionary that contains items of type LogicalP.
If I set LogicalP in SInstance to an initial state, the combobox text field shows empty. If I select the pulldown all my dictionary values are there. When I change the selection LogicalP in SInstance gets updated correctly. If I change Sinstance in C# the appropriate combobox value doesn't reflect the updated LogicalP from the pulldown.
I've set the binding mode to twoway with no luck. Any thoughts?
My Xaml:
<UserControl.Resources>
<ObjectDataProvider x:Key="PList"
ObjectType="{x:Type src:MainWindow}"
MethodName="GetLogPList"/>
</UserControl.Resources>
<DataTemplate DataType="{x:Type src:SInstance}">
<Grid>
<ComboBox ItemsSource="{Binding Source={StaticResource PList}}"
DisplayMemberPath ="Value.Name"
SelectedValuePath="Value"
SelectedValue="{Binding Path=LogicalP,Mode=TwoWay}">
</ComboBox>
</Grid>
</DataTemplate>
My C#:
public Dictionary<string, LogicalPType> LogPList { get; private set; }
public Dictionary<string, LogicalPType> GetLogPList()
{
return LogPList;
}
public class LogicalPType
{
public string Name { get; set; }
public string C { get; set; }
public string M { get; set; }
}
public class SInstance : INotifyPropertyChanged
{
private LogicalPType _LogicalP;
public string Name { get; set; }
public LogicalPType LogicalP
{
get { return _LogicalP; }
set
{
if (_LogicalP != value)
{
_LogicalP = value;
NotifyPropertyChanged("LogicalP");
}
}
}
#region INotifyPropertyChanged Members
#endregion
}
They are not looking at the same source.
You need to have SInstance supply both the LogPList and LogicalP.
_LogicalP is not connected to LogPList
If you want to different objects to compare to equal then you need to override Equals.
Here's my working solution. By moving the dictionary retrieval GetLogPList to the same class as that supplies the data (as suggested by Blam) I was able to get the binding to work both ways. I changed binding to a list rather than a dictionary to simplify the combobox
Here's the updated Xaml showing the new ItemsSource binding and removal of the SelectedValuePath:
<DataTemplate DataType="{x:Type src:SInstance}">
<Grid>
<ComboBox ItemsSource="{Binding GetLogPList}"
DisplayMemberPath ="Name"
SelectedValue="{Binding Path=LogicalP,Mode=TwoWay}">
</ComboBox>
</Grid>
</DataTemplate>
I then changed the dictionary LogPList to static so that it would be accessible to the class SInstance:
public static Dictionary<string, LogicalPType> LogPList { get; private set; }
Finally, I moved GetLogPList to the class SInstance as a property. Note again it's returning a list as opposed to a dictionary to make the Xaml a little simpler:
public class SInstance : INotifyPropertyChanged
{
public List<LogicalPType> GetLogPList
{
get { return MainWindow.LogPList.Values.ToList(); }
set { }
}
private LogicalPType _LogicalP;
public string Name { get; set; }
public LogicalPType LogicalP
{
get { return _LogicalP; }
set
{
if (_LogicalP != value)
{
_LogicalP = value;
NotifyPropertyChanged("LogicalP");
}
}
}
#region INotifyPropertyChanged Members
#endregion
}
I had a listbox of user controls and each usercontrol displays properties of the bounded data and bind a collection to custom control when the custom control changes the data the UI not updated my code is as follows :
ObservableCollection<Subscription> subscriptions = new ObservableCollection<Subscription> SubscriptionRepository.GetSubscriptions());
SubListBox.ItemsSource = subscriptions;
xaml :
<DataTemplate x:Key="MyDataTemplate">
<UserControls:SubscriptionUC />
</DataTemplate>
<ListBox x:Name="SubListBox" ItemTemplate="{StaticResource MyDataTemplate}">
</ListBox>
user control :
<TextBlock Text="{Binding Path=DaysAttended}" />
<cc:CustomControl SubscriptionSource="{Binding Path=SubscriptionDays,Mode=TwoWay}" />
Subscription class :
public class Subscription : INotifyPropertyChanged
{
public int SubscriptionTypeId { get; set; }
public DateTime StartDate { get; set; }
public DateTime EndDate { get; set; }
public ObservableCollection<SubscriptionDay> SubscriptionDays { get; set; }
public int DaysAttended { get { return SubscriptionDays.Count(d => d.Attended == true); } }
public void DayChanged()
{
RaisePropertyChanged("SubscriptionDays");
RaisePropertyChanged("DaysAttended");
}
}
DayChanged() is called from SubscriptionDay class when SubscriptionDay property changed and it is called but DaysAttended not updated.
You also need to have setter for DaysAttended property,For Two Way binding it is must that your property should have getter and setter .I hope this will help.
I am using the MVVM pattern in my project;
In my project I have a CheckedComboBoxEdit then bind to a Person List;
Public Class Person
{
Public Int Id { get; set; }
Public string Name { get; set; }
}
When User select some Items in CheckedComboBoxEdit, how can I get CheckedComboBoxEdit SelectedItems in my ViewModel?
You need a property on your ViewModel that binds to the CheckedComboBoxEdit SelectedItems property. You should probably look at related DevExpress posts.
<CheckedComboBoxEdit x:Name="cbPeople" SelectedItems="{Binding SelectedPeople}" ... />
I have a simple example where I'm creating a View consisting of a list box, and the list box displays a bunch of items. I'm wondering if I'm going about the creation of the View Model and Model classes correctly here. Use whatever value of correctly works in this context, I understand it's a bit subjective, but my current solution doesn't feel right. Here's a simplified version.
The ViewModels and Models:
namespace Example
{
public class ParentViewModel
{
public ParentViewModel()
{
// ... Create/Consume ChildViewModel * n
}
public List<ChildViewModel> ChildViewModels { get; set; }
}
public class ChildViewModel
{
public ChildViewModel()
{
// ... Create/Consume ChildModel
}
public ChildModel Model { get; set; }
}
public class ParentModel
{
public List<ChildModel> ChildModels { get; set; }
public ParentModel()
{
// ... Create/Consume ChildModel * n;
}
}
public class ChildModel
{
public ChildModel()
{
// ... Contains actual data.
}
public string Data { get; set; }
}
}
The View:
<Window x:Class="Example.View"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Example="clr-namespace:Example" Title="View" Height="300" Width="300"
DataContext="{StaticResource TheViewModel}">
<Window.Resources>
<Example:ParentViewModel x:Key="TheViewModel" />
</Window.Resources>
<Grid>
<ListBox Height="261" HorizontalAlignment="Left" Name="listBox1" VerticalAlignment="Top" Width="278" ItemsSource="{Binding ChildViewModels}"/>
</Grid>
In the proper code, the listbox will use a data template to display the child view models. But as you can see I'm not sure how the to instantiate the child related objects. It feels like the ParentViewModel will have a reference to the ParentModel and create ChildViewModel objects based on the ParentModel's ChildModel objects. Now I've said that it doesn't sound so daft, but I'd be interested in your thoughts.
You are on the right track.
The parent model would naturally contain a list of child models, e.g. a customer having multiple orders.
When ParentViewModel is created and loaded by a third-party, it is passed a ParentModel. Then the ParentViewModel will:
Assign the ParentModel to a local variable
Create a ChildViewModel for each ChildModel by passing the
ChildModel to the ChildViewModel constructor
Add each of those ChildViewModels to a list
By the way, you want
public List<ChildViewModel> ChildViewModels { get; set; }
to be
public ObservableCollection<ChildViewModel> ChildViewModels { get; set; }