I am working on the ability to add and delete rows in an observable collection.
Since the original post I have created a test app that only has the ability to delete rows from the observable collection. I populate the database externally then open it in this just to test the delete function which doesn't work. It executes the RemoveAt line, deletes from the Observable Collection but the view does not update. Here is all my code:
Model:
public class TestModel : ObservableObject
{
#region Properties
private Double id;
public Double ID
{
get { return id; }
set
{
id = value;
RaisePropertyChangedEvent("ID");
}
}
private string type;
public string Type
{
get { return type; }
set
{
type = value;
RaisePropertyChangedEvent("Type");
}
}
private decimal amount;
public decimal Amount
{
get { return amount; }
set
{
amount = value;
RaisePropertyChangedEvent("Amount");
}
}
private string notes;
public string Notes
{
get { return notes; }
set
{
notes = value;
RaisePropertyChangedEvent("Notes");
}
}
#endregion
}
Viewmodel:
public class MainWindowViewModel : ObservableObject
{
#region GetData
public MainWindowViewModel()
{
Transactions = DatabaseFunctions.getTransactionData();
}
#endregion
#region ObservableCollections
private ObservableCollection<TestModel> transactions;
public ObservableCollection<TestModel> Transactions
{
get { return transactions; }
set
{
transactions = value;
RaisePropertyChangedEvent("Transactions");
}
}
#endregion
#region Properties
public static string SharedWith;
private Double id;
public Double ID
{
get { return id; }
set
{
id = value;
RaisePropertyChangedEvent("ID");
}
}
private string type;
public string Type
{
get { return type; }
set
{
type = value;
RaisePropertyChangedEvent("Type");
}
}
private decimal amount;
public decimal Amount
{
get { return amount; }
set
{
amount = value;
RaisePropertyChangedEvent("Amount");
}
}
private string notes;
public string Notes
{
get { return notes; }
set
{
notes = value;
RaisePropertyChangedEvent("Notes");
}
}
#endregion
public void DeleteTransactionRow(List<TestModel> SelectedTransaction, int SelectedIndex)
{
Transactions.RemoveAt(SelectedIndex);
}
View:
<Window x:Class="OCTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:Properties="clr-namespace:OCTest.Properties"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid"
Title="Test" SizeToContent="WidthAndHeight"
xmlns:ViewModel="clr-namespace:OCTest.ViewModel">
<Window.DataContext>
<ViewModel:MainWindowViewModel/>
</Window.DataContext>
<Grid>
<xcdg:DataGridControl x:Name="TransactionsDataGrid" Grid.Row="0" ItemsSource="{Binding Transactions, Mode=TwoWay}" AutoCreateColumns="False" SelectionMode="Single">
<xcdg:DataGridControl.ContextMenu>
<ContextMenu>
<MenuItem Header="Delete Row" Click="DeleteTransactionRow_Click"/>
</ContextMenu>
</xcdg:DataGridControl.ContextMenu>
<xcdg:DataGridControl.Columns>
<xcdg:Column Title="Type" FieldName="Type" ReadOnly="True"/>
<xcdg:Column Title="Amount" FieldName="Amount">
<xcdg:Column.CellContentTemplate>
<DataTemplate>
<TextBlock Text="{Binding StringFormat={}{0:C}}"/>
</DataTemplate>
</xcdg:Column.CellContentTemplate>
</xcdg:Column>
<xcdg:Column Title="Notes" FieldName="Notes"/>
</xcdg:DataGridControl.Columns>
</xcdg:DataGridControl>
</Grid>
Code behind that deals with the delete command and passes needed information to the view model:
public partial class MainWindow : Window
{
MainWindowViewModel mainwindowviewmodel = new MainWindowViewModel();
public MainWindow()
{
InitializeComponent();
}
private void DeleteTransactionRow_Click(object sender, RoutedEventArgs e)
{
List<TestModel> selectedtransaction = TransactionsDataGrid.SelectedItems.Cast<TestModel>().ToList();
mainwindowviewmodel.DeleteTransactionRow(selectedtransaction, TransactionsDataGrid.SelectedIndex);
}
private void MouseRightButtonUpHandler(object sender, RoutedEventArgs e)
{
this.TransactionsDataGrid.SelectedItem = ((DataCell)sender).ParentRow.DataContext;
}
}
So hopefully someone can see why the RemoveAt doesn't update the view.
You need to set the DataContext of the MainWindow to your view model:
public MainWindow()
{
InitializeComponent();
DataContext = new MainWindowViewModel();
}
I'd also recommend looking into binding click events to commands in your view model rather than relying on the code behind.
Related
I struggle to refresh the data attached to the RADdatagrid. The view with the Datagrid shows the position of a team in a competition. Every time a new game is finished the view has to be updated automatically. The data is stored in a sqlite database and a simple sql query gets the positions from the database. A button in the view that calls the query method does the job but I want to update the grid directly after the finished game is stored. I implemented INotifyPropertyChanged but no result. I also tried to fire the button_click event but that also didn't bring me the result. I want to do this right but I am open to a quick and dirty solution. Here is a bit of my code:
<StackPanel Grid.Row="2" Orientation="Horizontal">
<TextBlock Grid.Row="2" Margin="40,0,0,5">Team Ranking</TextBlock>
<Button x:Name="RefreshViewButton" Command="{Binding Path=RefreshView}" Margin="40 0 0 0 " Click="RefreshViewButton_Click">Refresh</Button>
</StackPanel>
<StackPanel Grid.Row="6" Margin="0, 0, 50, 0" VerticalAlignment="Stretch">
<telerikGrid:RadDataGrid
AutoGenerateColumns="False"
x:Name="Datagrid"
BorderThickness="0"
ItemsSource="{x:Bind ViewModel.TeamResult, Mode=TwoWay}"
ColumnDataOperationsMode="Flyout"
GridLinesVisibility="None"
RelativePanel.AlignLeftWithPanel="True"
RelativePanel.AlignRightWithPanel="True"
UserEditMode="None" >
<telerikGrid:RadDataGrid.Columns>
<telerikGrid:DataGridNumericalColumn PropertyName="Rank" Header="Rank" SizeMode="Auto"/>
<telerikGrid:DataGridTextColumn PropertyName="Team_Naam" Header="TeamNaam" SizeMode="Auto"/>
<telerikGrid:DataGridTextColumn PropertyName="WedstrijdPunten" Header="WP" CanUserEdit="False" CanUserFilter="False" CanUserGroup="False" CanUserReorder="False" CanUserResize="False" CanUserSort="False" SizeMode="Auto" />
<telerikGrid:DataGridTextColumn PropertyName="PuntenVoor" Header="GP" SizeMode="Auto"/>
</telerikGrid:RadDataGrid.Columns>
</telerikGrid:RadDataGrid>
</StackPanel>
This is my view:
public sealed partial class TeamTotals : Page
{
public TeamResultsViewModel ViewModel { get; set; } = new TeamResultsViewModel();
public TeamTotals()
{
DataContext = ViewModel;
this.InitializeComponent();
}
public void RefreshViewButton_Click(object sender, RoutedEventArgs e)
{
ViewModel.LoadTeamResultsData();
}
}
My ViewModel:
public class TeamResultsViewModel : TeamModel
{
//public List<TeamModel> TeamResult = new List<TeamModel>();
public ObservableCollection<TeamModel> TeamResult = new ObservableCollection<TeamModel>();
TeamModel tm = new TeamModel();
public TeamResultsViewModel()
{
LoadTeamResultsData();
tm.PropertyChanged += Tm_PropertyChanged;
}
private void Tm_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
throw new NotImplementedException();
}
public void LoadTeamResultsData()
{
int i = 0;
if(TeamResult != null)
{
TeamResult.Clear();
}
try
{
string sql = "Select Team_Naam, WedstrijdPunten, PuntenVoor, PuntenTegen FROM Team WHERE KlasseId = 1 " +
"ORDER BY WedstrijdPunten DESC, PuntenVoor DESC LIMIT 10;";
var resultaat = SqliteDataAccess.LoadData<TeamModel>(sql, new Dictionary<string, object>());
foreach (var x in resultaat)
{
TeamResult.Add(x);
x.Rank = i++;
}
}
catch (Exception ex)
{
var messagedialog2 = new MessageDialog($"{ex}");
_ = messagedialog2.ShowAsync();
}
return;
}
}
and the model:
public class TeamModel : INotifyPropertyChanged
{
private int _id;
public int Id
{
get { return _id; }
set { _id = value; }
}
private int _klasseId;
public int KlasseId
{
get { return _klasseId; }
set { _klasseId = value; }
}
private string _team_naam;
public string Team_Naam
{
get { return _team_naam; }
set { _team_naam = value; }
}
private int _coachId;
public int CoachId
{
get { return _coachId; }
set { _coachId = value; }
}
private int _clubId;
public int ClubId
{
get { return _clubId; }
set { _clubId = value; }
}
private int _puntenVoor;
public int PuntenVoor
{
get { return _puntenVoor; }
set { _puntenVoor = value; }
}
private int _puntenTegen;
public int PuntenTegen
{
get { return _puntenTegen; }
set { _puntenTegen = value; }
}
private int _wedstrijdPunten;
public int WedstrijdPunten
{
get { return _wedstrijdPunten; }
set
{
_wedstrijdPunten = value;
OnPropertyChanged("WedstrijdPunten");
}
}
private int _rank;
public int Rank
{
get { return _rank; }
set { _rank = value; }
}
public List<SpelerModel> TeamLeden { get; set; } = new List<SpelerModel>();
public string Standen => $"{Team_Naam} : {PuntenVoor}";
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public override string ToString()
{
return Standen;
}
}
I use Prism. Data provider works correctly (SQLite here).
<ListBox ItemsSource="{Binding Path=CategoryList}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding Name}"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
public class ListsViewModel : BindableBase
{
private readonly IDataProvider _dataProvider;
private readonly IRegionManager _regionManager;
public DelegateCommand ClickAddCategory { get; set; }
private string categoryName;
public string CategoryName
{
get { return categoryName; }
set { SetProperty(ref categoryName, value); }
}
private ObservableCollection<ExtraCategory> categoryList;
public ObservableCollection<ExtraCategory> CategoryList
{
get
{
if (categoryList == null) return _dataProvider.GetCategoryList();
else return categoryList;
}
set { SetProperty(ref categoryList, value); }
}
public ListsViewModel(IRegionManager regionManager, IDataProvider dataProvider)
{
_dataProvider = dataProvider;
_regionManager = regionManager;
ClickAddCategory = new DelegateCommand(ClickedAddCategory);
//MessageBox.Show("Hello from " + this.ToString());
}
private void ClickedAddCategory()
{
ExtraCategory newCategoryFromForm = new ExtraCategory(CategoryName);
CategoryList.Add(newCategoryFromForm);
_dataProvider.AddCategory(newCategoryFromForm);
}
}
If I change the line:
CategoryList.Add(newCategoryFromForm);
to
CategoryList = _dataProvider.GetCategoryList();
everything would work fine because code inside set {} will run but that's not a solution. I would really appreciate some help. Also I really don't want to break MVVM pattern.
You want to put an ObservableCollection in a property without setter. And you want the value to stay the same.
private ObservableCollection<ExtraCategory> categoryList;
public ObservableCollection<ExtraCategory> CategoryList
{
get
{
if (categoryList == null) return _dataProvider.GetCategoryList();
else return categoryList;
}
set { SetProperty(ref categoryList, value); }
}
This gives you a new ObservableCollection everytime you call CategoryList.get, i.e. CategoryList.Add(newCategoryFromForm); fetches a new list, adds the new item, then discards the list (returning a value from a property's getter does not magically set a backing field).
I'd do it this way:
public ObservableCollection<ExtraCategory> CategoryList { get; }
and in constructor:
CategoryList = _dataProvider.GetCategoryList();
use and install nuget package PropertyChange.Fody.
Your class would look like this:
public class ListsViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private readonly IDataProvider _dataProvider;
private readonly IRegionManager _regionManager;
public DelegateCommand ClickAddCategory { get; set; }
public string CategoryName { get; set; }
public ObservableCollection<ExtraCategory> CategoryList { get; set; }
public ListsViewModel(IRegionManager regionManager, IDataProvider dataProvider)
{
_dataProvider = dataProvider;
_regionManager = regionManager;
ClickAddCategory = new DelegateCommand(ClickedAddCategory);
CategoryList = _dataProvider.GetCategoryList();
//MessageBox.Show("Hello from " + this.ToString());
}
private void ClickedAddCategory()
{
ExtraCategory newCategoryFromForm = new ExtraCategory(CategoryName);
CategoryList.Add(newCategoryFromForm);
_dataProvider.AddCategory(newCategoryFromForm);
}
}
I'm sure it will work perfectly
If what you want is to update the list use a method and bind a command to execute when you want to refresh
I have a View that has ItemsControl and Wrappanel inside it. By using Drag&Drop files I am trying to update the Wrappanel. I have all data related to files in a JsonFile. There is no problem with appending data to json file. It is working. When I redebug the solution I can see the list of files in Wrappanel.
public partial class StorageView : Window
{
readonly StorageViewModel _storageViewModel;
public StorageView()
{
_storageViewModel = new StorageViewModel();
InitializeComponent();
}
private void TopMenuBorder_MouseDown(object sender, MouseButtonEventArgs e)
{
if (e.ChangedButton == MouseButton.Left)
{
this.DragMove();
}
}
// Wrappanel Drop
private void StorageBrowser_Drop(object sender, DragEventArgs e)
{
string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
List<string> files2 = new List<string>();
foreach (var file in files)
{
files2.Add(file);
}
_storageViewModel.TempFiles = files2;
}
// Drag Enter
private void StorageBrowser_DragEnter(object sender, DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop))
e.Effects = DragDropEffects.Move;
else
e.Effects = DragDropEffects.None;
}
private void CreateNewFolder_Click(object sender, RoutedEventArgs e)
{
}
}
<ScrollViewer Grid.Row="1" VerticalScrollBarVisibility="Auto">
<StackPanel Orientation="Vertical">
<Button Command="{Binding AddFileCommand}" Content="Add File"/>
<ItemsControl ItemsSource="{Binding Files, UpdateSourceTrigger=PropertyChanged}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel Name="StorageBrowser" Background="White" Drop="StorageBrowser_Drop" DragEnter="StorageBrowser_DragEnter" VerticalAlignment="Stretch" AllowDrop="True" Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Label Content="{Binding FileName}"/>
<!--<comp:FileCard/>-->
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</StackPanel>
</ScrollViewer>
public class StorageViewModel : Screen, INotifyPropertyChanged
{
#region Commands
private ICommand _addFileCommand;
private bool canExecute = true;
public bool CanExecute
{
get
{
return this.canExecute;
}
set
{
if (this.canExecute == value)
{
return;
}
this.canExecute = value;
}
}
public ICommand AddFileCommand
{
get
{
return _addFileCommand;
}
set
{
_addFileCommand = value;
}
}
#endregion
#region Notify
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
#region FileModel
private int _id;
private string _fileName;
private string _fullFileName;
private decimal _fileSize;
private string _fileType;
private string _fileIcon;
private string _fileExtension;
private string _fileSizeType;
private string _fileImage;
private string _fullFileSize;
private string _fileOwner;
private DateTime? _created;
private DateTime? _modified;
private DateTime? _lastAccessed;
private bool _isVersionFile;
private List<FileModel> _fileVersions;
public List<FileModel> FileVersions
{
get { return _fileVersions; }
set { _fileVersions = value; OnPropertyChanged(nameof(FileVersions)); }
}
public bool IsVersionFile
{
get { return _isVersionFile; }
set { _isVersionFile = value; OnPropertyChanged(nameof(IsVersionFile)); }
}
public DateTime? LastAccess
{
get { return _lastAccessed; }
set { _lastAccessed = value; OnPropertyChanged(nameof(LastAccess)); }
}
public DateTime? Modified
{
get { return _modified; }
set { _modified = value; OnPropertyChanged(nameof(Modified)); }
}
public DateTime? Created
{
get { return _created; }
set { _created = value; OnPropertyChanged(nameof(Created)); }
}
public string FileOwner
{
get { return _fileOwner; }
set { _fileOwner = value; OnPropertyChanged(nameof(FileOwner)); }
}
public string FullFileSize
{
get { return _fullFileSize; }
set { _fullFileSize = value; OnPropertyChanged(nameof(FullFileSize)); }
}
public string FileImage
{
get { return _fileImage; }
set { _fileImage = value; OnPropertyChanged(nameof(FileImage)); }
}
public string FileSizeType
{
get { return _fileSizeType; }
set { _fileSizeType = value; OnPropertyChanged(nameof(FileSizeType)); }
}
public string FileExtension
{
get { return _fileExtension; }
set { _fileExtension = value; OnPropertyChanged(nameof(FileExtension)); }
}
public string FileIcon
{
get { return _fileIcon; }
set { _fileIcon = value; OnPropertyChanged(nameof(FileIcon)); }
}
public string FileType
{
get { return _fileType; }
set { _fileType = value; OnPropertyChanged(nameof(FileType)); }
}
public decimal FileSize
{
get { return _fileSize; }
set { _fileSize = value; OnPropertyChanged(nameof(FileSize)); }
}
public string FullFileName
{
get { return _fullFileName; }
set { _fullFileName = value; OnPropertyChanged(nameof(FullFileName)); }
}
public string FileName
{
get { return _fileName; }
set { _fileName = value; OnPropertyChanged(nameof(FileName)); }
}
public int Id
{
get { return _id; }
set { _id = value; OnPropertyChanged(nameof(Id)); }
}
#endregion
#region Collections
private List<string> _tempFiles { get; set; }
public List<string> TempFiles { get { return _tempFiles; } set { _tempFiles = value; OnPropertyChanged("TempFiles"); } }
private ObservableCollection<FileModel> _files { get; set; }
public ObservableCollection<FileModel> Files { get { return _files; } set { _files = value; OnPropertyChanged("Files"); } }
#endregion
public StorageViewModel()
{
AddFileCommand = new RelayCommand(AddFile, param=>this.canExecute);
Files = new ObservableCollection<FileModel>(Documentive.GCS.DataAccess.GCSDataAccess.GetDataFromJson());
}
public void AddFile(object o)
{
foreach (var file in TempFiles)
{
Documentive.GCS.DataAccess.GCSDataAccess.AppendDataToFileJson(file);
}
Files.Clear();
Files = Documentive.GCS.DataAccess.GCSDataAccess.GetDataFromJson();
}
}
There is all my codes. I need to update ItemsControl and list new files' data in wrappanel. There is no problem with the FileCard UserControl, I just tried to list data by using label.(just a test)
I don't know if there is a problem with Drag&Drop event and its codes or not.
Thanks.
I think you might actually have a few problems here.
First of all, implement DragOver instead of DragEnter, otherwise you won't be able to drop files into it.
Secondly, get rid of the ScrollViewer, and let ItemsControl manage the scrolling itself. There are a number of reasons for this (not the least of which is virtualization), but just trust me: never put an ItemsControl inside a ScrollViewer.
Next, get rid of the vertical StackPanel. By placing everything in a stack panel you're making your ItemsControl size itself according to the number of items it's already bound to, so dropping files into that big blank area underneath it won't do anything. Set your WrapPanel's background to a color you can actually see, and make sure it's covering the area of the page you think it is. Best way to do that is to use a parent Grid to do layout and then populate that with your Button and ItemsControl, setting your alignment properties accordingly.
The biggest problem with this code though is that your TopMenuBorder_MouseDown handler is updating TempFiles, but your ItemsControl is binding to Files.
The button click does not fire if I use the DelegateCommand from Prism. If I write a command class for button click and not use Prism, then it works. This is my code with Prism:
This is my View XAML:
<Window x:Class="MVVMPractice2.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:prism="http://prismlibrary.com/"
prism:ViewModelLocator.AutoWireViewModel="True"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Label Content="Customer Name" HorizontalAlignment="Left" Margin="0,0,0,292.8"></Label>
<Label Name="lblName" HorizontalAlignment="Left" Margin="108,0,0,292.8" Width="37" Content="{Binding TxtCustomerName}"></Label>
<Label Content="Sales Amount" HorizontalAlignment="Left" Margin="0,28,0,264.8"></Label>
<TextBox Name="lblAmount" HorizontalAlignment="Left" Margin="101,28,0,264.8" Width="44" Text="{Binding TxtAmount}"></TextBox>
<Label Content="Buying Habits" HorizontalAlignment="Left" Margin="0,56,0,236.8"></Label>
<Label Name="lblBuyingHabits" HorizontalAlignment="Left" Margin="108,56,0,236.8" Width="52" Background="{Binding LblAmountColor}"></Label>
<Label Content="Married" HorizontalAlignment="Left" Margin="0,84,0,208.8" Width="62"></Label>
<CheckBox Name="chkMarried" HorizontalAlignment="Left" Margin="102,84,0,208.8" IsChecked="{Binding IsMarried}"></CheckBox>
<Label Content="Tax" HorizontalAlignment="Left" Margin="0,112,0,180.8"></Label>
<TextBlock Name="lblTax" HorizontalAlignment="Left" Margin="108,117,0,175.8" Width="37" Text="{Binding TaxAmount}"></TextBlock>
<Button Name="btnTax" Content="Calculate Tax" Margin="118,158,287.4,123.8" Command="{Binding UpdateCommand}"></Button>
</Grid>
</Window>
And the ViewModel:
public class MainWindowViewModel : BindableBase
{
//instantiate the model
private Customer customer = new Customer();
//property for button click command
private DelegateCommand UpdateCommand;
//constructor to instantiate the buttons click command
public MainWindowViewModel()
{
UpdateCommand = new DelegateCommand(customer.CalculateTax, customer.IsValid);
}
//this property maps customer name from model to the view
public string TxtCustomerName
{
get { return customer.CustomerName; }
set { customer.CustomerName = value; }
}
//this property maps amount from model to the view
public string TxtAmount
{
get { return Convert.ToString(customer.Amount); }
set { customer.Amount = Convert.ToDouble(value); }
}
//this property maps and transforms color from model to the view
public string LblAmountColor
{
get
{
if (customer.Amount > 2000)
{
return "Blue";
}
else if (customer.Amount > 1500)
{
return "Red";
}
return "Yellow";
}
}
//this property maps and transforms married from model to the view
public bool IsMarried
{
get
{
if (customer.Married == "Married")
{
return true;
}
else if (customer.Married == "UnMarried")
{
return false;
}
return false;
}
set
{
if (value)
{
customer.Married = "Married";
}
else
{
customer.Married = "UnMarried";
}
}
}
//this property maps tax from model to the view
public string TaxAmount
{
get { return Convert.ToString(customer.Tax); }
set { customer.Tax = Convert.ToDouble(value); }
}
}
and the Model:
public class Customer
{
//model property
private string customerName = "Ivan";
public string CustomerName
{
get { return customerName; }
set { customerName = value; }
}
//model property
private double amount = 2000;
public double Amount
{
get { return amount; }
set { amount = value; }
}
//model property
private string married = "Married";
public string Married
{
get { return married; }
set { married = value; }
}
//model property
private double tax;
public double Tax
{
get { return tax; }
set { tax = value; }
}
//this modifier calculates the tax
public void CalculateTax()
{
if (amount > 2000)
{
tax = 20;
}
else if (amount > 1000)
{
tax = 10;
}
else
{
tax = 5;
}
}
//this modifier validates the amount
public bool IsValid()
{
if (amount < 0)
{
return false;
}
else
{
return true;
}
}
}
As pointed to in the comment above, changing the field to a property helps, and firing NotifyPropertyChanged (removed irrelevant parts):
public class MainWindowViewModel : BindableBase
{
//property for button click command
public DelegateCommand UpdateCommand { get; }
//constructor to instantiate the buttons click command
public MainWindowViewModel()
{
UpdateCommand = new DelegateCommand(() => {
customer.CalculateTax();
OnPropertyChanged( () => TaxAmount );
}, customer.IsValid);
}
//this property maps tax from model to the view
public string TaxAmount
{
get { return Convert.ToString(customer.Tax); }
set { customer.Tax = Convert.ToDouble(value); }
}
}
Alternatively, make Customer implement INotifyPropertyChanged and use something like PropertyObserver to pass the events to the view.
Update
Managed to fix the selectedIndex problem. I'd forgotten to set SelectedItem as well and naturally that caused a few issues.
So at 9AM this morning we got our 24 hour assignment and I have hit a brick wall.
We're supposed to create a program that allows a supervisor to Add and delete Employees and add Working Sessions, total hours and total earnings. But I am having some problems succesfully implementing this following the MVVM-Pattern. For some reason my Bindings simply aren't working and the only Solution I can see is someone looking over my project and helping me troubleshoot it.
Here is my code - I'm very sorry about having to post the entire thing but given that I have no clue where the problem is I did not see any other options. :
EmployeeModel
[Serializable]
public class WorkSessions : ObservableCollection<WorkSessionModel>
{
public WorkSessions()
{
}
}
[Serializable]
public class WorkSessionModel : INotifyPropertyChanged
{
private DateTime _dateTime;
private string _id;
private double _hours;
public WorkSessionModel()
{
}
public DateTime DateTime
{
get { return _dateTime; }
set
{
_dateTime = value;
NotifyPropertyChanged("DateTime");
}
}
public string ID
{
get { return _id; }
set
{
_id = value;
NotifyPropertyChanged("ID");
}
}
public double Hours
{
get { return _hours; }
set
{
_hours = value;
NotifyPropertyChanged("Hours");
NotifyPropertyChanged("TotalHours");
}
}
[field: NonSerialized]
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
WorkSessionModel
[Serializable]
public class WorkSessions : ObservableCollection<WorkSessionModel>
{
public WorkSessions()
{
}
}
[Serializable]
public class WorkSessionModel : INotifyPropertyChanged
{
private DateTime _dateTime;
private string _id;
private double _hours;
public WorkSessionModel()
{
}
public DateTime DateTime
{
get { return _dateTime; }
set
{
_dateTime = value;
NotifyPropertyChanged("DateTime");
}
}
public string ID
{
get { return _id; }
set
{
_id = value;
NotifyPropertyChanged("ID");
}
}
public double Hours
{
get { return _hours; }
set
{
_hours = value;
NotifyPropertyChanged("Hours");
NotifyPropertyChanged("TotalHours");
}
}
[field: NonSerialized]
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
EmployeeViewModel
public class EmployeeViewModel : ViewModelBase
{
private Employees _employeesModel = new Employees();
public Employees EmployeesView = new Employees();
public ObservableCollection<WorkSessionModel> WorkSessions { get; set; }
private string _id = "0";
private string _name = "noname";
private double _wage = 0;
private int _totalhours = 0;
public string ID
{
get { return _id; }
set { _id = value; RaisePropertyChanged("ID"); }
}
public string Name
{
get { return _name; }
set
{
_name = value;
RaisePropertyChanged("Name");
}
}
public double Wage
{
get { return _wage; }
set
{
_wage = value;
RaisePropertyChanged("Wage");
}
}
public int TotalHours
{
get { return _totalhours; }
set
{
_totalhours = value;
RaisePropertyChanged("TotalHours");
}
}
private EmployeeModel _selectedEmployee = new EmployeeModel();
public EmployeeModel SelectedEmployee
{
get { return _selectedEmployee; }
set
{
_selectedEmployee = value;
RaisePropertyChanged("SelectedEmployee");
}
}
private int _selectedEmployeeIndex;
public int SelectedEmployeeIndex
{
get { return _selectedEmployeeIndex; }
set
{
_selectedEmployeeIndex = value;
RaisePropertyChanged("SelectedEmployeeIndex");
}
}
#region RelayCommands
// Employee Relay Commands
public RelayCommand EmployeeAddNewCommand { set; get; }
public RelayCommand EmployeeDeleteCommand { set; get; }
public RelayCommand EmployeeNextCommand { set; get; }
public RelayCommand EmployeePrevCommand { set; get; }
public RelayCommand EmployeeTotalHoursCommand { get; set; }
#endregion
public EmployeeViewModel()
{
InitCommands();
}
private void InitCommands()
{
EmployeeAddNewCommand = new RelayCommand(EmployeeAddNewExecute, EmployeeAddNewCanExecute);
EmployeeDeleteCommand = new RelayCommand(EmployeeDeleteNewExecute, EmployeeDeleteCanExecute);
EmployeeNextCommand = new RelayCommand(EmployeeNextExecute, EmployeeNextCanExecute);
EmployeePrevCommand = new RelayCommand(EmployeePrevExecute, EmployeePrevCanExecute);
//EmployeeTotalHoursCommand = new RelayCommand(EmployeeTotalHoursExecute, EmployeeTotalHoursCanExecute);
}
//private void EmployeeTotalHoursExecute()
//{
// _selectedEmployee.TotalHours();
//}
//private bool EmployeeTotalHoursCanExecute()
//{
// return true;
//}
private void EmployeeAddNewExecute()
{
EmployeeModel newEmployee = new EmployeeModel();
EmployeesView.Add(newEmployee);
_employeesModel.Add(newEmployee);
SelectedEmployee = newEmployee;
}
private bool EmployeeAddNewCanExecute()
{
return true;
}
private void EmployeeDeleteNewExecute()
{
if (MessageBox.Show("You are about delete all submissions for Employee," + SelectedEmployee.Name + "(" + SelectedEmployee.ID +")\r\nAre you sure?", "This is a Warning!", MessageBoxButton.YesNo) == MessageBoxResult.Yes)
{
_employeesModel.Remove(SelectedEmployee);
EmployeesView.Remove(SelectedEmployee);
}
}
private bool EmployeeDeleteCanExecute()
{
if (SelectedEmployee != null)
return true;
else return false;
}
private void EmployeeNextExecute()
{
SelectedEmployeeIndex++;
}
private bool EmployeeNextCanExecute()
{
if (SelectedEmployeeIndex < EmployeesView.Count - 1)
return true;
return false;
}
private void EmployeePrevExecute()
{
SelectedEmployeeIndex--;
}
private bool EmployeePrevCanExecute()
{
if (SelectedEmployeeIndex > 0)
return true;
return false;
}
}
View
public partial class MainWindow : Window
{
public EmployeeViewModel EmployeeViewModel = new EmployeeViewModel();
public MainWindow()
{
InitializeComponent();
menu_employee.DataContext = EmployeeViewModel;
sp_employees.DataContext = EmployeeViewModel;
datagrid_employees.ItemsSource = EmployeeViewModel.EmployeesView;
grid_selectedEmployee.DataContext = EmployeeViewModel.SelectedEmployee;
}
}
I can see a few problems with your code:
When the SelectedIndex is updated, SelectedItem remains the same and vice versa.
It looks like your data binding is out of order:
The DataContext property cascades down to every child of a certain dependency object.
The code in the MainWindow constructor should probably be replaced by:
this.DataContext = EmployeeViewModel;
Then in XAML set the rest of the properties using Data Binding. The problem in your situation is that the DataContext of the selectedemployee is only set once. This means if you select another employee, then it will not update.
An example for your SelectedEmployee grid:
<Grid Name="grid_selectedEmployee" DataContext="{Binding SelectedEmployee,
UpdateSourceTrigger=PropertyChanged}">...</Grid>
One of the biggest things I see is you are setting properties, not binding them.
For example,
datagrid_employees.ItemsSource = EmployeeViewModel.EmployeesView;
You are telling your DataGrid that it's ItemsSource should be that specific object. You need to bind it to that value so you are telling it to point to that property instead. This will make your UI correctly reflect what's in your ViewModel
The other huge red flag I see is your ViewModel referencing something called and EmployeeView which leads me to believe your View and ViewModel too closely tied together.
Your ViewModel should contain all your business logic and code, while the View is usually XAML and simply reflects the ViewModel in a user-friendly way.
The View and the ViewModel should never directly reference each other (I have had my View reference my ViewModel in some rare occasions, but never the other way around)
For example, an EmployeesViewModel might contain
ObservableCollection<Employee> Employees
Employee SelectedEmployee
ICommand AddEmployeeCommand
ICommand DeleteEmployeeCommand
while your View (XAML) might look like this:
<StackPanel>
<StackPanel Orientation="Horizontal">
<Button Content="Add" Command="{Binding AddEmployeeCommand}" />
<Button Content="Delete" Command="{Binding DeleteEmployeeCommand}" />
</StackPanel>
<DataGrid ItemsSource="{Binding Employees}"
SelectedItem="{Binding SelectedEmployee}">
... etc
</DataGrid>
<UniformGrid DataContext="{Binding SelectedEmployee}" Columns="2" Rows="4">
<TextBlock Text="ID" />
<TextBox Text="{Binding Id}" />
... etc
</UniformGrid >
</StackPanel>
And the only thing you should be setting is the DataContext of the entire Window. Usually I overwrite App.OnStartup() to start up my application:
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
var view = new MainWindow();
var vm = new EmployeesViewModel;
view.DataContext = vm;
view.Show();
}
}
Although I suppose in your case this would also work:
public MainWindow()
{
InitializeComponent();
this.DataContext = new EmployeesViewModel();
}