DataGrid Not Being Populated

Question

Consider this class:

Public Class Transaction
    Implements INotifyPropertyChanged

    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
    << Various properties >>
End Class

and this:

Public Class TransactionEx
    Inherits Transaction
    << Additional properties >>
End Class

In code-behind, I load data from a database (I have verified this is working correctly) into

Private _TransactionsEx As New ObservableCollection(Of TransactionEx)
Public Property TransactionsEx As ObservableCollection(Of TransactionEx)
    Get
        Return _TransactionsEx
    End Get
    Set(value As ObservableCollection(Of TransactionEx))
        _TransactionsEx = value
    End Set
End Property

The Property TransactionsEx serves as the ItemsSource for a DataGrid, however, no data appears in the DataGrid. I think the problem might be that the CollectionChanged event is not triggered so the DataGrid doesn't know that there is data to display.

If that is the case, what do I have to do trigger that event. Or do you see any other issue?

Answer 1

Hi,@Roger Schlueter. Welcome Microsoft Q&A.

I add data to the collection to test it can successfully populate the DataGrid. You could try to refer to the code below and check your code. Please let me know if there is any problem.

<Window.DataContext>
        <local:MainWindowVM/>
    </Window.DataContext>
    <Grid>
        <DataGrid Width="400" Height="300" ItemsSource="{Binding TransactionsEx }"/>
    </Grid>

Public Class MainWindowVM

    Private _TransactionsEx As New ObservableCollection(Of TransactionEx)
    Public Property TransactionsEx As ObservableCollection(Of TransactionEx)
        Get
            Return _TransactionsEx
        End Get
        Set(value As ObservableCollection(Of TransactionEx))
            _TransactionsEx = value
        End Set
    End Property



    Public Sub New()
        _TransactionsEx.Add(New TransactionEx() With {
            .Id = 1,
            .Name = "user1",
            .Detail = "detail1"
        })
        _TransactionsEx.Add(New TransactionEx() With {
            .Id = 2,
            .Name = "user2",
            .Detail = "detail2"
        })
        _TransactionsEx.Add(New TransactionEx() With {
            .Id = 3,
            .Name = "user3",
            .Detail = "detail3"
        })

    End Sub


End Class
Public Class TransactionEx
    Inherits Transaction


    Private _detail As String

    Public Property Detail As String
        Get
            Return _detail
        End Get
        Set(ByVal value As String)


            Me._detail = value
            NotifyPropertyChanged("Detail")

        End Set
    End Property




End Class

Public Class Transaction
    Implements INotifyPropertyChanged



    Private _id As Integer

    Public Property Id As Integer
        Get
            Return _id
        End Get
        Set(ByVal value As Integer)


            Me._id = value
            NotifyPropertyChanged("Id")

        End Set
    End Property

    Private _name As String

    Public Property Name As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)


            Me._name = value
            NotifyPropertyChanged("Name")

        End Set
    End Property
    Public Event PropertyChanged As PropertyChangedEventHandler _
            Implements INotifyPropertyChanged.PropertyChanged

    Public Sub NotifyPropertyChanged(ByVal propertyName As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
    End Sub
End Class

The result:

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