First time I program an app in XAML, I learned from different sources and I am trying to make an app. Right now I am working on making a good looking chat but ran into an error that I cannot solve at all.
The part that bugs start in the MainWindow:
<chat:ChatViewModel/>
This calls the user control CharViewModel that creates the chat. Here is the XAML part of this user control:
<UserControl.Resources>
<DataTemplate DataType="{x:Type local:IncomingMessage}">
<Grid >
<Border Background="Orange" CornerRadius="15 15 0 15" Margin="10 12">
<TextBlock Margin="15" TextWrapping="Wrap" Foreground="CadetBlue" Text="{Binding MessageContent}"/>
</Border>
<TextBlock Text="Thu 5:45PM" HorizontalAlignment="Left" VerticalAlignment="Bottom" FontSize="10" Margin="10 0"/>
</Grid>
</DataTemplate>
<DataTemplate DataType="{x:Type local:OutgoingMessage}">
<Grid >
<Border Background="Gray" CornerRadius="15 15 0 15" Margin="10 12">
<TextBlock Margin="15" TextWrapping="Wrap" Foreground="CadetBlue" Text="{Binding MessageContent}"/>
</Border>
<TextBlock Text="Thu 5:45PM" HorizontalAlignment="Right" VerticalAlignment="Bottom" FontSize="10" Margin="10 0"/>
</Grid>
</DataTemplate>
</UserControl.Resources>
<UserControl.DataContext>
<local:MessageList/>
</UserControl.DataContext>
<Grid>
<ItemsControl ItemsSource="{Binding Messages}"/>
</Grid>
Here is the C# code:
public partial class ChatViewModel : UserControl
{
public ChatViewModel()
{
InitializeComponent();
}
}
This is how my MessageList looks like :
class MessageList : ViewModelBase
{
public MessageList()
{
Messages = new ObservableCollection<Message>();
}
public ObservableCollection<Message> Messages { get; set; }
}
To finish, this is the code in the MainWindow.cs that creates the list of message from a text file. Each message is of the form "David/Hi how are u?" in the text file:
var ListMessage = new MessageList();
using (StreamReader file = new StreamReader("../Utilisateur/Chat.txt"))
{
string text;
while ((text = file.ReadLine()) != null)
{
string[] list = text.Split('/');
if (list[0] == "David")
{
ListMessage.Messages.Add(new OutgoingMessage { MessageContent = list[1] });
}
else
{
ListMessage.Messages.Add(new IncomingMessage { MessageContent = list[1] });
}
}
}
With the message class looking like this:
public class Message : ViewModelBase
{
///Sender Name
public string SenderName { get; set; }
///Text of the message
private string _messageContent;
public string MessageContent
{
get
{
return _messageContent;
}
set
{
_messageContent = value;
OnPropertyChanged("MessageContent");
}
}
///True if message has been read
public bool MessageRead;
///Time the message was sent
public DateTimeOffset MessageSentTime { get; set; }
}
And the ViewModelBase that I copied from the internet because I don't fully understand how it works
public class ViewModelBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged([CallerMemberName] string propName = null)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propName));
}
}
}
Here I have a text file with each line representing a message of the form "NameOfTheTender/Message".
Then I want to display the messages as small bubble, orange and on the left side of the window if I received the message, gray and on the right side if I sent it. For the moment nothing shows on the window.
How the window looks like right now
<local:MessageList/> in the UserControl's DataContext and new MessageList() in the Window's code behind create two different MessageList instances. Adding items to one of them has no effect on the other.
Your UserControl should not set its own DataContext. Remove this DataContent assignment from the UserControl's XAML:
<UserControl.DataContext>
<local:MessageList/>
</UserControl.DataContext>
In order to make the UserControl bind to the MessageList instance created in the MainWindow, just assign that to the Window's DataContext:
var ListMessage = new MessageList();
DataContext = ListMessages;
The value of the DataContext property will now be inherited by the UserControl.
Related
I'm learning MVVM pattern and I have a simple issue.
I have created a class whose properties I want to bind into text boxes inside a Dialog (in this case I only have one property):
public class NewObjectClass : ObservableObject
{
private string _name;
public string Name
{
get { return _name; }
set
{
_name = value;
OnPropertyChanged("Name");
}
}
}
This is the ViewModel of the Dialog:
class ObjCreationViewModel : ObservableObject
{
// Class whose properties I want to bind in text boxes
private NewObjectClass _newObject;
public NewObjectClass NewObject
{
get { return _newObject; }
set { _newObject = value;
OnPropertyChanged("NewObject");
}
}
// String to test binding
private string _test;
public string Test
{
get { return _test; }
set { _test = value; }
}
// Create new object view
private DelegateCommand _createNewObject;
public DelegateCommand CreateNewObjectCmd => _createNewObject ?? (_createNewObject = new DelegateCommand(CreateNewObject));
void CreateNewObject()
{
// Do things in the future
}
public ObjCreationViewModel()
{
// Instance of New Object
NewObjectClass NewObject = new NewObjectClass();
// New object property that I want to show in TextBox
NewObject.Name = "Why this one is not working?";
// String text that works
Test = "Why this is working?";
}
}
And finally this is the view:
<UserControl x:Class="AOE.MVVM.View.ObjCreationView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:AOE.MVVM.View"
xmlns:viewmodel="clr-namespace:AOE.MVVM.ViewModel"
mc:Ignorable="d"
MinHeight="500" MinWidth="500">
<UserControl.DataContext>
<viewmodel:ObjCreationViewModel/>
</UserControl.DataContext>
<Border Grid.ColumnSpan="4" CornerRadius="20"
Background="White" BorderBrush="Black" BorderThickness="1.5">
<Grid HorizontalAlignment="Stretch">
<Grid.RowDefinitions>
<RowDefinition Height="30"/>
<RowDefinition/>
<RowDefinition Height="30"/>
</Grid.RowDefinitions>
<StackPanel Grid.Row="1">
<StackPanel Orientation="Horizontal">
<Label Margin="10" Content="Object name:" Style="{StaticResource DescriptionLabelStyle}"/>
<TextBox x:Name="TextObjectName" Width="200" Height="25" Text="{Binding NewObject.Name, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"/>
</StackPanel>
</StackPanel>
<Button Grid.Row="1" Margin="5" Name="CreateBtn" Width="75" Height="30" Content="Create" FontFamily="Verdana" Foreground="#007BC0" FontWeight="Bold" Background="Transparent" BorderThickness="3" BorderBrush="#007BC0" VerticalAlignment="Bottom" Command="{Binding CreateNewObjectCmd}"/>
</Grid>
</Border>
The issue is that I can't bind the property Name of "NewObject" into the text box, however if I bind "Test", It works properly.
I want to show in the textbox the property value and also if I change the value in the textbox, change the property value of the instance "NewObject".
Anybody could tell me what is wrong?
PD "ObservableObject class that implements PropertyChange event":
public class ObservableObject : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged([CallerMemberName] string propertyname = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyname));
}
}
The line
NewObjectClass NewObject = new NewObjectClass();
defines a local variable NewObject, but does not set the property NewObject.
Change it to
NewObject = new NewObjectClass();
I am working with data binding and tree views and I am not able to get my TreeView to populate in my WPF. I think I am relatively close, just a small tweak somewhere, but I can't seem to find it.
Here's my Project class:
public class Project
{
public Project(string Name, bool isFolder, Project ParentFolder)
{
this.Name = Name;
this.isFolder = isFolder;
Children = new List<Project>();
if (ParentFolder == null)
{
Path = Name;
}
else
{
Path = ParentFolder.Path + " > " + Name;
}
}
public string Path { get; private set; }
public string Name { get; set; }
public bool isFolder { get; set; }
public List<Project> Children { get; set; }
public IEnumerable<Project> ChildFolders
{
get
{
return Children.Where(p => p.isFolder);
}
}
public object Icon
{
get
{
if (isFolder)
{
return 0; // return folder icon
}
else
{
return 1; // return project icon
}
}
}
public IEnumerable<Project> SearchRecursively(string SearchString)
{
return GetAllChildren.Where(p => p.Name.Contains(SearchString));
}
private List<Project> GetAllChildren
{
get
{
List<Project> allChildren = new List<Project>();
foreach(Project child in Children)
{
allChildren.AddRange(child.GetAllChildren);
}
return allChildren;
}
}
}
}
Here is my MaiWindow.xaml.cs class that I will be using to make test data:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.BuildData();
}
private void BuildData()
{
List<Project> parents = new List<Project>();
Project parentOne = new Project("Apple", true, null);
Project parentTwo = new Project("Samsung", true, null);
Project parentThree = new Project("Google", true, null);
parents.Add(parentOne); parents.Add(parentTwo); parents.Add(parentThree);
Project appleMacBook = new Project("Mac", false, parentOne);
Project appleIpad = new Project("iPad", false, parentOne);
Project appleiPhone = new Project("iPhone", false, parentOne);
Project samsungGalaxy = new Project("Galaxy", false, parentTwo);
Project samsungNote = new Project("Note", false, parentTwo);
Project googlePixel = new Project("Pixel", false, parentThree);
Project googleChromecast = new Project("Chromecast", false, parentThree);
parents[0].Children.Add(appleMacBook); parents[0].Children.Add(appleIpad); parents[0].Children.Add(appleiPhone);
parents[1].Children.Add(samsungGalaxy); parents[1].Children.Add(samsungNote);
parents[2].Children.Add(googlePixel); parents[2].Children.Add(googleChromecast);
}
}
}
And here is my XAML where I am trying to display the TreeView. Right now, it is just blank. I would appreciate any tips.
<TreeView x:Name="Hierarchy" Grid.Column="4" HorizontalAlignment="Left" Height="631" Margin="0,58,0,0" Grid.Row="1" VerticalAlignment="Top" Width="265"
ItemsSource="{Binding parents}">
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding parents}" DataType="{x:Type self:Project}">
<TreeViewItem Header="{Binding Name}"></TreeViewItem>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
Edit:
Here's the Property class:
public string Name
{
get
{
return name;
}
set
{
name = value;
OnPropertyChanged("Name");
}
}
private string name { get; set; }
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
if(PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
XAML:
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding ChildFolders}">
<StackPanel Orientation="Horizontal" >
<Image Source="{Binding Icon}" Margin="5, 5, 5, 5"></Image>
<TextBox Text="{Binding Name, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}" BorderThickness="0" FontSize="16" Margin="5"/>
</StackPanel>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
So, this doesn't seem to be firing the change event. I know this because Path is set as Name + ">". When I change the Name, Path is not reflecting the change. It only shows what my previous value for Name was, if that makes sense.
if (ParentFolder == null)
{
Path = Name;
}
else
{
Path = ParentFolder.Path + " > " + Name;
}
Edit:
public Project(string Name, bool isFolder, Project ParentFolder)
{
this.Name = Name;
this.isFolder = isFolder;
Children = new List<Project>();
this.ParentFolder = ParentFolder;
}
public string Path
{
get
{
return this.ParentFolder + " > " + this.Name;
}
set
{
this.Path = Path;
}
}
XAML:
<TextBox x:Name="FolderNameBox" Grid.Column="1" Background="White" Grid.Row="1" Grid.ColumnSpan="5"
Margin="0,0,287,654.333" VerticalContentAlignment="Center"
Padding="6" FontSize="16"
IsReadOnly="True"
Text="{Binding ElementName=Hierarchy, Path=SelectedItem.Path, UpdateSourceTrigger=PropertyChanged}">
</TextBox>
<TextBox x:Name="SearchProjectsBox" Grid.Column="5" Background="White" Grid.Row="1" Text="Search Projects"
Margin="47.333,0,0,654.333" VerticalContentAlignment="Center" Foreground="LightGray" Padding="6" FontSize="16" HorizontalAlignment="Left" Width="268" GotFocus="TextBox_GotFocus" LostFocus="TextBox_LostFocus"/>
<TreeView x:Name="Hierarchy" Grid.Column="4" HorizontalAlignment="Left" Height="631" Margin="0,58,0,0" Grid.Row="1" VerticalAlignment="Top" Width="226"
ItemsSource="{Binding Projects}">
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding ChildFolders}">
<StackPanel Orientation="Horizontal" >
<Image Source="{Binding Icon}" Margin="5, 5, 5, 5"></Image>
<TextBox Text="{Binding Name, UpdateSourceTrigger=PropertyChanged}" BorderThickness="0" FontSize="16" Margin="5"/>
</StackPanel>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
<Grid Grid.ColumnSpan="2" Grid.Column="4" HorizontalAlignment="Left" Height="631" Margin="245,58,0,0" Grid.Row="1" VerticalAlignment="Top" Width="540">
<ScrollViewer HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden">
<ListView Margin="0,0,10,0" Name="ProjectView" ItemsSource="{Binding Projects}" FontSize="16" Foreground="Black">
<ListView.View>
<GridView ColumnHeaderContainerStyle="{StaticResource GridHeader}">
<GridViewColumn Header="Name" Width="200" DisplayMemberBinding="{Binding ElementName=Hierarchy, Path=SelectedItem.Name, UpdateSourceTrigger=PropertyChanged}"></GridViewColumn>
<GridViewColumn Header="Directory" Width="328" DisplayMemberBinding="{Binding ElementName=Hierarchy, Path=SelectedItem.Path, UpdateSourceTrigger=PropertyChanged}"></GridViewColumn>
</GridView>
</ListView.View>
</ListView>
</ScrollViewer>
</Grid>
</Grid>
The Path updates too but when it I see it it will display the path of the project rather than the fired change of name. It changes in real-time but doesn't save the String value..only registers that a change has happened.
Heres my Property Change too.
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
if(PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
You have a few problems here.
ItemsSource="{Binding parents}"
Here's parents:
private void BuildData()
{
List<Project> parents = new List<Project>();
You're asking XAML to examine all the methods in the codebehind class, looking for local variables named parents. This isn't a reasonable request.
There are a few requirements if you want to bind to parents: It must be...
A public...
Property (not a field -- it needs a get block)...
Of whatever object is your TreeView's DataContext.
None of those are true.
Two more things -- not required, but a very good idea:
Make it ObservableCollection<T> rather than List<T>, so that it will notify the UI of added or removed items.
The class that owns it should be a viewmodel class, not your window/usercontrol. When we say "viewmodel", we mean it implements INotifyPropertyChanged and raises PropertyChanged when its property values change. Again, this is about keeping the UI informed of changes.
Keeping the UI informed is what bindings are all about: They listen for changes in the viewmodel and update the UI.
So you need a main viewmodel that looks like this:
public class ViewModelBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
// C#6
/*
protected virtual void OnPropertyChanged([System.Runtime.CompilerServices.CallerMemberName] string propName = null) =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propName));
*/
protected virtual void OnPropertyChanged(string propName)
{
var handler = PropertyChanged;
if (handler != null) {
handler(this, new PropertyChangedEventArgs(propName));
}
}
}
public class MainViewModel : ViewModelBase
{
private ObservableCollection<Project> _projects;
public ObservableCollection<Project> Projects {
get { return _projects; }
set {
if (value != _projects) {
_projects = value;
OnPropertyChanged(nameof(Projects));
}
}
}
public void BuildData() {
Projects = new ObservableCollection<Project>();
// do the rest of the stuff
}
}
And you should rewrite your Project class as a ProjectViewModel derived from ViewModelBase, make it raise PropertyChanged in the same way, and use ObservableCollection<Project> for Children.
And in your main window...
public MainWindow()
{
InitializeComponent();
var vm = new MainViewModel();
vm.BuildData();
DataContext = vm;
}
Your XAML needs a little work, too.
Projects has a capitalized name now
For the item template, you are binding to the property of the child item which provides the tree view item's children. That's the Children property of your Project class.
A datatemplate tells XAML how to present the content of a control. The tree creates a TreeViewItem with a Project as its DataContext, and then uses your HierarchicalDataTemplate to turn that DataContext into some kind of visual content. You don't use the template to create a TreeViewItem; you use it to create the visual stuff in the TreeViewItem.
So here's the new XAML:
<TreeView
x:Name="Hierarchy"
ItemsSource="{Binding Projects}"
Grid.Column="4"
HorizontalAlignment="Left"
Height="631"
Margin="0,58,0,0"
Grid.Row="1"
VerticalAlignment="Top"
Width="265"
>
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Children}">
<Label Content="{Binding Name}" />
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
There's no reason to get in the habit of DataContext = this;. Once you start that, the next thing you know you'll be doing it in a UserControl and coming here asking why all your bindings to it in the parent XAML are broken. Dependency properties are a bigger hassle than INPC, and you end up with code that ought to be in a viewmodel mixed into your MainWindow code. If you use viewmodelsit's the easiest thing in the world to shuffle your UI around. Maybe you want the original content of your main window to be just one of three tab pages in the main window. Keeping code separated properly makes that kind of thing much simpler.
So I have a simple UDP chat app from a WinForm project, which I wanted to look a little bit better, so I am re-making it in WPF. As I realized I can easily put 2 or more TextBlocks inside of a ListItem, I wanted to display the last message of each chat, like so:
But I have no Idea on how to edit those TextBlocks :( I literary just started with WPF, so I bet I just made a duplicate, but because of that, I don't even know how to search for this issue.
Here is the custom ListBox:
<ListBox x:Name="myList" HorizontalAlignment="Left" Width="264" ScrollViewer.VerticalScrollBarVisibility="Hidden" ScrollViewer.HorizontalScrollBarVisibility="Disabled" BorderThickness="0,1,1,0" MouseLeftButtonUp="myList_MouseLeftButtonUp" Margin="0,25,0,0">
<ListBox.ItemTemplate>
<DataTemplate>
<Border BorderBrush="LightGray" BorderThickness="0,0,0,1" Width="250">
<DockPanel Margin="0,7">
<Ellipse Name="ellipse" Margin="5" DockPanel.Dock="Left" Style="{DynamicResource elstyle}">
</Ellipse>
<TextBlock Text="{Binding Name}" DockPanel.Dock="Top" Margin="0,0,0,7" FontWeight="Bold" MaxWidth="250"></TextBlock>
<TextBlock Text="{Binding ID}" DockPanel.Dock="Top" Visibility="Hidden" FontSize="1.333"></TextBlock>
<TextBlock x:Name="last_message" Text="{Binding LastMessage}" DockPanel.Dock="Bottom" MaxWidth="250"></TextBlock>
</DockPanel>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
This is simplified model to show the principal but if you would create view model class that implement INotifyPropertyChanged interface to hold your item data
public class MyItem : INotifyPropertyChanged
{
private string _name;
private string _id;
private string _lastMessage;
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
var handler = this.PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
public string Name
{
get { return _name; }
set
{
_name = value;
OnPropertyChanged("Name");
}
}
public string ID
{
get { return _id; }
set
{
_id = value;
OnPropertyChanged("ID");
}
}
public string LastMessage
{
get { return _lastMessage; }
set
{
_lastMessage = value;
OnPropertyChanged("LastMessage");
}
}
}
and then in your window
public partial class MainWindow : Window
{
private readonly ObservableCollection<MyItem> _myItems = new ObservableCollection<MyItem>();
public MainWindow()
{
InitializeComponent();
myList.ItemsSource = _myItems;
_myItems.Add(new MyItem { Name = "name", ID = "id", LastMessage = "last message" });
_myItems[0].LastMessage = "new message";
}
}
and then you don't operate on myList control anymore but on _myItems list and its items. If you add/remove item in the collection it will add/remove item in the UI, if you change property of an item it will update bound property in the UI
I'm facing a problem in my WPF project at the moment. At this moment I have a Viewmodel which has a Manager (to communicate with the repo).
internal class TicketViewModel
{
private TicketManager mgr;
public IEnumerable<Ticket> List { get; set; }
public TicketViewModel()
{
mgr = new TicketManager();
List = mgr.GetTickets();
}
}
I've managed to bind this list to the Listbox in my MainWindow. The next step is that I need to add an extra ticket to the list and also pass this through the manager. The problem is I need two parameters from some Controls in the MainWindow. From MVVM perspective I need to use bound Commands on e.g. a Button to communicate with the viewmodel as my viewmodel can't/may not access controls from the window. Is using parameterized Commands the way to go here?
The next problem is that the Listbox won't update I guess. This is the code:
<ListBox x:Name="listboxTix" BorderThickness="0" ItemsSource="{Binding List}">
<ListBox.ItemTemplate>
<DataTemplate>
<Border BorderBrush="Bisque" Background="Beige" BorderThickness="2">
<StackPanel Width="250">
<TextBlock Text="{Binding TicketNumber}" />
<TextBlock Text="{Binding Text}" />
<TextBlock Text="{Binding State}" />
</StackPanel>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I found that using a CompareableCollection is the way to go here, but then I still have to read all the Tickets again after adding a new Ticket.
Thanks in advance,
Hicy
okay here is the code.
Lets say you have three textboxes on MainWindow(since you have three Textblocks.) so Your MainWindow.xaml looks like
<Window.DataContext>
<local:MyViewModel/>--set's your viewModel
</Window.DataContext>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="250*"/>
<RowDefinition Height="90"/>
<RowDefinition Height="30"/>
</Grid.RowDefinitions>
<ListBox Grid.Row="0" x:Name="listboxTix" BorderThickness="0" ItemsSource="{Binding List}">
<ListBox.ItemTemplate>
<DataTemplate>
<Border BorderBrush="Bisque" Background="Beige" BorderThickness="2">
<StackPanel Width="250">
<TextBlock Text="{Binding TicketNumber}" />
<TextBlock Text="{Binding Text}" />
<TextBlock Text="{Binding State}" />
</StackPanel>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<TextBox x:Name="TicketNumber" Grid.Row="1" TextWrapping="Wrap" Text="{Binding Path=Text}" VerticalAlignment="Top" Width="120"/>
<TextBox x:Name="Text" Grid.Row="1" TextWrapping="Wrap" Text="{Binding Path=State}" />
<TextBox x:Name="State" Grid.Row="1" TextWrapping="Wrap" Text="{Binding Path=TicketNumber}" />
<Button Content="Button" Command="{Binding Path=MainCommand}" Grid.Row="2"/>
</Grid>
and I am assuming that you have some class called class Ticket which contain these three members
Class Ticket
{
public int TicketNumber { get; set; }
public string Text { get; set; }
public string State { get; set; }
}
Now in class TicketManager we fill it with some dummy data
class TicketManager
{
ObservableCollection<Ticket> tl = new ObservableCollection<Ticket>();
internal ObservableCollection<Ticket> GetTickets()
{
tl.Add(new Ticket() { State = "State1", Text = "Text1", TicketNumber = 1 });
tl.Add(new Ticket() { State = "State2", Text = "Text2", TicketNumber = 2 });
tl.Add(new Ticket() { State = "State3", Text = "Text3", TicketNumber = 3 });
return tl;
}
}
and in your Mainwindow ViewModel lets call it MyViewModel.cs we add
class MyViewModel:INotifyPropertyChanged
{
private TicketManager mgr;
public ObservableCollection<Ticket> List { get; set; }
private string text;
private string state;
private int ticketNumber;
private readonly DelegateCommand<object> MyButtonCommand;
public Class1()
{
mgr = new TicketManager();
List = mgr.GetTickets();
MyButtonCommand = new DelegateCommand<object>((s) => { AddListToGrid(text, state, ticketNumber); }, (s) => { return !string.IsNullOrEmpty(text) && !string.IsNullOrEmpty(state); });
}
private void AddListToGrid(string text, string state, int ticketNumber)
{
List.Add(new Ticket() {Text=text,State=state,TicketNumber=ticketNumber });
}
public DelegateCommand<object> MainCommand
{
get
{
return MyButtonCommand;
}
}
public string Text
{
get
{
return text;
}
set
{
text = value;
OnPropertyChanged("Text");
MyButtonCommand.RaiseCanExecuteChanged();
}
}
public string State
{
get
{
return state;
}
set
{
state = value;
OnPropertyChanged("State");
MyButtonCommand.RaiseCanExecuteChanged();
}
}
public int TicketNumber
{
get
{
return ticketNumber;
}
set
{
ticketNumber = value;
OnPropertyChanged("TicketNumber");
MyButtonCommand.RaiseCanExecuteChanged();
}
}
private void OnPropertyChanged(string p)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(p));
}
public event PropertyChangedEventHandler PropertyChanged;
}
You can Modify the code in anyway you want
This ViewModel implements fewthings which are very important from MVVM point of view
1) INotifyPropertyChanged
2) WPF Delegate Command
P.S:The code is tested and it runs as expected
Don't get hung up on MVVM it is simply a separation of data from a view, and models are shared between the two with a majority of the business logic (on a shared component) should be performed on the VM; it is not a religion just a three tiered data system. IMHO
If your button needs to do an operation, have it make a call, most likely in the code behind, to a method on the VM which handles the business logic, updates the list with the new item and notifies the manager.
I would bind the list in question to an ObservableCollection which can notify upon insert/delete of an item.
im building a UserControl MyUserControl that has his own ViewModel MyUserControlViewModel. MyUserControl contains 6 VehicleSelectionBlock (V1, ... V6). VehicleSelectionBlock is a UserControl i've made. it has 3 RadioButton: car, train, bus; all are of enum type Vehicle and of the same GroupName VehicleGroup.
my goal is to represent each of MyUserControl's VehicleSelectionBlocks in MyUserControlViewModel.
to make my self clear: in MyUserControlViewModel i want to be able to know&change what RadioButton is checked in every one of the 6 VehicleSelectionBlock. i think my main problem is not the converter but rather the DataContex - i'm not sure how to set it correctly for each of the controllers.
iv'e tried Binding (which is the obvious solution). i tried reading here, here , and here. unfortunately neither one helped my acheive my goal.
my code is below - im kinda new to wpf and data binding in generally. i've read almost every chapter in this tutorial but still lost sometimes.
please help me get through this and understand better the DataContex concept.
ty
MyUserContlor.xaml.cs:
namespace Project01
{
/// <summary>
/// Interaction logic for MyUserContlor.xaml
/// </summary>
public partial class MyUserContlor : UserControl
{
public MyUserContlorViewModel ViewModel { get; set; }
public MyUserContlor()
{
ViewModel = new MyUserContlorViewModel();
InitializeComponent();
this.DataContext = ViewModel;
}
private void BtnImReady_OnClick(object sender, RoutedEventArgs e)
{
//this code is irrelevant to the question
throw NotImplementedException();
}
}
}
MyUserContlor.xaml:
<UserControl x:Class="Project01.MyUserContlor"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:loc="clr-namespace:Project01"
mc:Ignorable="d"
HorizontalContentAlignment="Center" VerticalContentAlignment="Center">
<Viewbox Stretch="Uniform">
<StackPanel>
<loc:VehicleSelectionBlock Name="V1"/>
<loc:VehicleSelectionBlock Name="V2"/>
<loc:VehicleSelectionBlock Name="V3"/>
<loc:VehicleSelectionBlock Name="V4"/>
<loc:VehicleSelectionBlock Name="V5"/>
<loc:VehicleSelectionBlock Name="V6"/>
<Button x:Name="BtnImReady" Click="BtnImReady_OnClick">Im Ready!</Button>
</StackPanel>
</Viewbox>
</UserControl>
MyUserContlorViewModel.cs:
namespace Project01
{
public class MyUserContlorViewModel : INotifyPropertyChanged
{
public MyUserContlorViewModel()
{
VehicleArr = new MyViewModel_Vehicle[6];
PropertyChanged+=MyUserControlViewModel_PropertyChanged;
}
public MyViewModel_Vehicle[] VehicleArr;
public event PropertyChangedEventHandler PropertyChanged;
public PropertyChangedEventHandler GetPropertyChangedEventHandler() { return PropertyChanged; }
private void MyUserControlViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
//might be useful
throw NotImplementedException();
}
}
//this class should represent a VehicleSelectionBlock
public class MyViewModel_Vehicle
{
public Vehicle VehicleSelected {get; set;}
MyViewModel_Vehicle(){}
MyViewModel_Vehicle(Vehicle v){ VehicleSelected = v;}
}
}
VehicleSelectionBlock.xaml:
<UserControl x:Class="Project01.VehicleSelectionBlock"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:Project01"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid DataContext="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}">
<Border VerticalAlignment="Center" HorizontalAlignment="Center" Background="GhostWhite"
BorderBrush="Gainsboro" BorderThickness="1">
<StackPanel >
<Label Content="{Binding Name}"
FontWeight="Bold" HorizontalContentAlignment="Center"></Label>
<RadioButton GroupName="VehicleGroup" >car</RadioButton>
<RadioButton GroupName="VehicleGroup">train</RadioButton>
<RadioButton GroupName="VehicleGroup" IsChecked="True">bus</RadioButton>
</StackPanel>
</Border>
</Grid>
</UserControl>
VehicleSelectionBlock.xaml.cs:
namespace Project01
{
/// <summary>
/// Interaction logic for VehicleSelectionBlock.xaml
/// </summary>
public partial class VehicleSelectionBlock : UserControl
{
public VehicleSelectionBlock()
{
InitializeComponent();
}
public VehicleSelectionBlock(String name)
{
name = Name;
InitializeComponent();
}
public static readonly DependencyProperty NameProperty = DependencyProperty.Register(
"Name", typeof (String), typeof (VehicleSelectionBlock), new PropertyMetadata(default(String)));
public String Name
{
get { return (String) GetValue(NameProperty); }
set { SetValue(NameProperty, value); }
}
}
public enum Vehicle { Car, Train, Bus}
}
here is a quick solution. keep in mind that the code needs to change if you want to add more values to your Vehicle enum.
the MyUserControlViewModel.cs file
public class MyUserControlViewModel
{
public MyUserControlViewModel()
{
VehicleArr = new VehicleViewModel[6];
for (int i = 0; i < 6;i++ )
VehicleArr[i] = new VehicleViewModel();
}
public VehicleViewModel[] VehicleArr { get; set; }
}
this will expose your 6 items. They could be more. As a result they will be displayed in an ItemsControl, as you will see later.
public class VehicleViewModel:ViewModelBase
{
private bool isCar, isTrain, isBus;
public bool IsCar
{
get { return isCar; }
set
{
if (isCar == value) return;
isCar = value;
OnChanged("IsCar");
}
}
public bool IsTrain
{
get { return isTrain; }
set
{
if (isTrain == value) return;
isTrain = value;
OnChanged("IsTrain");
}
}
public bool IsBus
{
get { return isBus; }
set
{
if (isBus == value) return;
isBus = value;
OnChanged("IsBus");
}
}
}
instances of VehicleViewModel will contain your radio selection using 3 bool properties. this is the solution disadvantage. If you want more values you'll have to add more properties. you can see this inherits ViewModelBase. ViewModelBase just implements INPC so i'm not going to put it here. ViewModelBase also exposes the OnChange method that triggers the INPC event.
displaying the list can be done in your MyUserControl by using an ItemsControl like below.
<ItemsControl ItemsSource="{Binding VehicleArr}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<loc:VehicleControl />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
each item is also a UserControl. The VehicleControl user control is just a StackPanel that displays the RadioButons. This can be seen below.
<StackPanel Orientation="Horizontal">
<RadioButton Content="Car" Margin="5" VerticalAlignment="Center" IsChecked="{Binding Path=IsCar, Mode=TwoWay}"/>
<RadioButton Content="Train" Margin="5" VerticalAlignment="Center" IsChecked="{Binding Path=IsTrain, Mode=TwoWay}"/>
<RadioButton Content="Bus" Margin="5" VerticalAlignment="Center" IsChecked="{Binding Path=IsBus, Mode=TwoWay}"/>
</StackPanel>
please notice that each RadioButton is bound to one of the 3 properties in the VehicleViewModel instance.
Once you press your button you should have all the selections recorded. if you want you could have a function that returns an enum value by analysing the 3 bool properties if that is what you need.
the best solution will be to get rid of the radio buttons and replace them with combo boxes. in this way you can change the enum members and everything will continue to work without changing anything else. this might look as below.
public class VehicleViewModel:ViewModelBase
{
private Vehicle selOption;
private readonly Vehicle[] options;
public VehicleViewModel()
{
this.options = (Vehicle[])Enum.GetValues(typeof(Vehicle));
}
public Vehicle[] Options { get { return options; } }
public Vehicle SelectedOption
{
get { return selOption; }
set
{
if (selOption == value) return;
selOption = value;
OnChanged("SelectedOption");
}
}
}
and for the view:
<ItemsControl ItemsSource="{Binding VehicleArr}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<ComboBox ItemsSource="{Binding Options}"
SelectedItem="{Binding SelectedOption, Mode=TwoWay}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
You can do directly in the code-behind of your control (in the default constructor)
public VehicleSelectionBlock()
{
InitializeComponent();
this.DataContext = new MyUserContlorViewModel ();
}
You can also do that in XAML (http://msdn.microsoft.com/en-us/library/ms746695(v=vs.110).aspx) declaration, as you wish.