I am trying to learn about C# mvvm and wpf, so i decided to make a simple project(a book&readers managing application for a library) and now i am a little lost so i would really appreciate some help. In my view i have a listview displaying the readers, and a bunch of textboxes bound to the selected item of the listview(name, adress,etc). The listview is bound to an observable collection of readers created from a database table(Readers) with Linq2SQL.
Below the textboxes i have a few buttons (Clear/Add/Save/Delete).
The problems i am having are that the "selected item" of the listview, seems null if i try to execute some commands when i click the buttons.
when i click the clear button, if i have a breakpoint on the selected item(reader), it shows that it gets null/empty spaced, but the textboxes dont clear; If in the Clear method in use the SelectedReader property, and assign empty spaces to its attributes, the selected item in the listview also clears(because its bound to Reader's FullName property)
i have other problems on adding a new reader, and saving changes, and i assume its because of wrong linq queries but i hope i can fix the current ones and move on afterwards.
What should i do?
ViewModel
public class MainWindowViewModel : ViewModelBase
{
private Reader selectedReader;
private ObservableCollection<Reader> readerList;
public MainWindowViewModel()
{
SelectedReader = new Reader()
{
FullName = "",
SerialNumber = "",
IdNumber = "",
Adress = "",
AltContactMethods = ""
};
BookDBDataContext rdb = new BookDBDataContext();
ReadersList = new ObservableCollection<Reader>(rdb.Readers);
AddR = new TblQryCommand(AddToDb);
EditR = new TblQryCommand(EditToDb);
DeleteR = new TblQryCommand(DeleteFromDb);
ClearR = new TblQryCommand(ClearReaderFields);
}
public TblQryCommand AddR { get; private set; }
public TblQryCommand EditR { get; private set; }
public TblQryCommand DeleteR { get; private set; }
public TblQryCommand ClearR { get; private set; }
//Reader List
public ObservableCollection<Reader> ReadersList
{
get { return readerList; }
set
{
if (readerList != value)
{
readerList = value;
RaisePropertyChanged();
}
}
}
public Reader SelectedReader
{
get { return selectedReader; }
set
{
if (selectedReader != value)
{
selectedReader = value;
RaisePropertyChanged();
}
}
}
public void AddToDb()
{
BookDBDataContext db = new BookDBDataContext();
Reader r = new Reader
{
FullName = SelectedReader.FullName,
SerialNumber = SelectedReader.SerialNumber,
IdNumber = SelectedReader.IdNumber,
Adress = SelectedReader.Adress,
AltContactMethods = SelectedReader.AltContactMethods
};
db.Readers.InsertOnSubmit(r);
db.Readers.Context.SubmitChanges();
}
public void DeleteFromDb()
{
}
public void EditToDb()
{
}
public void ClearReaderFields()
{
SelectedReader = new Reader
{
Id = 0,
FullName = string.Empty,
SerialNumber = string.Empty,
IdNumber = string.Empty,
Adress = string.Empty,
AltContactMethods = string.Empty
};
}
View:
<ListView Name="listviewReaders" ItemsSource="{Binding ReadersList}" SelectedItem="{Binding SelectedReader,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" Width="140" Height="180" Margin="10,68,492,281">
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding FullName}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<TextBox x:Name="txtBxFullName" HorizontalAlignment="Left" Height="22" Margin="211,68,0,0" TextWrapping="Wrap" Text="{Binding ElementName=listviewReaders, Path=SelectedItem.FullName, Mode=TwoWay, UpdateSourceTrigger=Explicit}" VerticalAlignment="Top" Width="315"/>
<TextBox x:Name="txtBxSerialNumber" HorizontalAlignment="Left" Height="22" Margin="211,95,0,0" TextWrapping="Wrap" Text="{Binding ElementName=listviewReaders, Path=SelectedItem.SerialNumber, Mode=TwoWay, UpdateSourceTrigger=Explicit}" VerticalAlignment="Top" Width="315"/>
<TextBox x:Name="txtBxIdNumber" HorizontalAlignment="Left" Height="22" Margin="211,122,0,0" TextWrapping="Wrap" Text="{Binding ElementName=listviewReaders, Path=SelectedItem.IdNumber, Mode=TwoWay, UpdateSourceTrigger=Explicit}" VerticalAlignment="Top" Width="315"/>
<TextBox x:Name="txtBxAdress" HorizontalAlignment="Left" Height="22" Margin="211,149,0,0" TextWrapping="Wrap" Text="{Binding ElementName=listviewReaders, Path=SelectedItem.Adress, Mode=TwoWay, UpdateSourceTrigger=Explicit}" VerticalAlignment="Top" Width="315"/>
<TextBox x:Name="txtBxAltContactMethods" HorizontalAlignment="Left" Height="22" Margin="211,176,0,0" TextWrapping="Wrap" Text="{Binding ElementName=listviewReaders, Path=SelectedItem.AltContactMethods, Mode=TwoWay, UpdateSourceTrigger=Explicit}" VerticalAlignment="Top" Width="315"/>
<Button x:Name="btnReader_Clear" Content="Clear" Command="{Binding ClearR}" HorizontalAlignment="Left" Margin="211,228,0,0" VerticalAlignment="Top" Width="75"/>
<Button x:Name="btnReader_Save" Content="Save" Command="{Binding EditR}" HorizontalAlignment="Left" Margin="291,228,0,0" VerticalAlignment="Top" Width="75"/>
<Button x:Name="btnReader_Add" Content="Add New" Command="{Binding AddR}" HorizontalAlignment="Left" Margin="371,228,0,0" VerticalAlignment="Top" Width="75"/>
<Button x:Name="btnReader_Delete" Content="Delete" Command="{Binding DeleteR}" HorizontalAlignment="Left" Margin="451,228,0,0" VerticalAlignment="Top" Width="75"/>
