I have been trying to figure out the proper way to bind an ObservableCollection of a class to a ListBox with a TextBox DataTemplate. I've tried to implement the code in WPF binding: Set Listbox Item text color based on property but that hasn't gotten me very far as of yet. I'm new to WPF DataBinding, having at most programatically set the ItemsSource in simple cases.
I have this class
public class item
{
public string guid;
public bool found;
public bool newItem;
public Brush color;
}
and the following ObservableCollection
public ObservableCollection<item> _items;
public Window()
{
InitializeComponent();
_items = new ObservableCollection<item>();
}
Elsewhere in the code I add items to the collection via
_items.Add(new item() { guid = sdr.GetString(0), found = false, newItem = false, color = Brushes.Red });
Here's simplified XAML for the ListBox
<ListBox x:Name="ListBox_Items">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text=GUID_HERE Foreground=COLOR_HERE/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I've tried several different ways to get this to work properly, yet for none of them the ListBox is updating. Is anyone able to help point me in the right direction here?
Four things:
Your item class needs to use public properties:
public class item
{
public string guid { get; set; }
public bool found { get; set; }
public bool newItem { get; set; }
public Brush color { get; set; }
}
You need to set the ItemsSource to the collection, and set the current DataContext
public Window()
{
InitializeComponent();
DataContext = this;
_items = new ObservableCollection<item>();
ListBox_Items.ItemsSource = _items;
}
You need to update your DataTemplate to use the property names of your POCO
<ListBox x:Name="ListBox_Items">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding guid}" Foreground="{Binding color}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I think you forgot to bind your ListBox to collection itself.
Your XAML should look like:
<ListBox x:Name="ListBox_Items" ItemsSource="{Binding _items}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text=GUID_HERE Foreground=COLOR_HERE/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
And if you want to change properties of items in your collection (and that changes to appear on UI) you should implement INotifyPropertyChanged (see more at MSDN) interface in "item" class.
Related
I have a class defined like:
public class Agent
{
public int Id { get; set; }
public string Category { get; set; }
// rest removed for brevity
}
Then, in WPF, I get the data as List and pass it to DataContext as this:
List<Agent> agents; // this includes my data
this.DataContext = agents;
And in .xaml part I want to list the Category field of each object. I have something like this:
<ListBox
Name="agentCategoryListBox"
Grid.Row="2"
Grid.Column="1"
ItemSource="{Binding Path=Category"} />
But this doesn't seem to work correctly. Any ideas?
Let me help you to do this in the correct way as Alex suggested.
Create a list and populate it in ViewModel like this
ViewModel
public class MainWindowViewModel : INotifyPropertyChanged
{
public MainWindowViewModel()
{
agents = new ObservableCollection<Agent>();
LoadData();
}
private void LoadData()
{
agents.Add(new Agent { Id = 1, Category = "a" });
agents.Add(new Agent { Id = 2, Category = "b" });
agents.Add(new Agent { Id = 3, Category = "c" });
}
}
In XAML, Make your list and use data template like this:
<Window.Resources>
<DataTemplate x:Key="AItemTemplate">
<TextBlock Text="{Binding Category}"></TextBlock>
</DataTemplate>
</Window.Resources>
<ListBox ItemsSource="{Binding agents}"
ItemTemplate="{StaticResource AItemTemplate}"></ListBox>
That is it !!
Normally the DataContext would be a view model class that would contain the list of agents; then you can bind the ItemsSource to that list. Any of the many examples that deal with listbox will be pretty straight forward when it comes to that. Not really sure how the binding should look like if the list itself is the DataContext.
Then once the ItemsSource is set to a list of agents, if you want to show the Category in the list, the simpler way is to set DisplayMemberPath to "Category".
I suggest looking into MVVM and learning to apply it, it's an invaluable concept in my opinion.
You try to bind your listbox to a string property.
You can try this :
Give a name to your user control for exemle myUC
Add a property to your user control :
public List<Agent> AgentList { get; set; };
Fill your agentlist :
this.AgentList = //fill method
And bind your listbox like this :
<ListBox
Name="agentCategoryListBox"
Grid.Row="2"
Grid.Column="1"
ItemSource="{Binding Path=AgentList, ElementName=myUC"} />
may be this will give you an idea:
http://www.c-sharpcorner.com/forums/wpf-datacontext-binding-with-listbox
The fastest way to get what you want is :
<ListBox
Name="agentCategoryListBox"
Grid.Row="2"
DisplayMemberPath="Category"
Grid.Column="1"
ItemSource="{Binding Path=."} />
ItemsSource is binded directly to your Datacontext (which is your list) And then you tell to your ListBox to display the property Category.
But the proper way would have been :
1 - Create a DataContext
public class AgentsDC
{
public List<Agent> Agents { get; set; }
}
2 - Give this class as DataContext
this.DataContext = new AgentsDC();
3 - Bind all these things
<ListBox
Name="agentCategoryListBox"
Grid.Row="2"
DisplayMemberPath="Category"
Grid.Column="1"
ItemSource="{Binding Path=Agents"} />
I also would suggest you to use MVVM. But if you do not want to then try this.
XAML:
<ListBox Name="AgentCategoryListBox" ItemsSource="{Binding}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Category}" d:DataContext="{d:DesignData}" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
CS:
public MainWindow()
{
InitializeComponent();
List<Agent> agents = new List<Agent>
{
new Agent
{
Category = "Category"
}
};
DataContext = agents;
}
public class Agent
{
public string Category
{
get;
set;
}
}
I am teaching myself how to bind classes to XAML objects. I can't find anything on data within lists. Either that or I don't know the terminology very well. I want to make a combobox that is tied to the list, displaying the name of each Item in the Items list. How would I bind this to the combobox?
class Section
{
List<Item> Items = new List<Item>();
}
class Item
{
private string _name;
public string Name
{
get { return _name; }
set { _name = value; }
}
}
Try This,
<ComboBox ItemsSource="{Binding Items}" DisplayMemberPath="Name" />
Make your Items collection as a property.
public List<Item> Items { get; set;}
Section Class should be public and make it as your DataContext
Assuming Section is the current DataContext :
<ComboBox ItemsSource="{Binding Items}"
DisplayMemberPath="Name" />
I'm trying to get the databinding I need to work with a ListBox.
I've parsed some data from a text file to a ObservableCollection<ViewModel> but the data isn't updating in the ListBox.
Here's some information:
The data which is written to from the parser:
class MainData
{
private static ObservableCollection<GroupViewModel> groupModelList = new ObservableCollection<GroupViewModel>();
public static ObservableCollection<GroupViewModel> GroupModelList
{
get { return groupModelList; }
}
}
What GroupViewModel holds (not everything but it's all the same):
class GroupViewModel : INotifyPropertyChanged
{
private GroupModel groupModel;
public event PropertyChangedEventHandler PropertyChanged;
public GroupViewModel()
{
groupModel = new GroupModel();
}
public string Name
{
get { return groupModel.name; }
set
{
if (groupModel.name != value)
{
groupModel.name = value;
InvokePropertyChanged("Name");
}
}
}
...
}
And what GroupModel Holds:
class GroupModel
{
public string name { get; set; }
}
This is how the parser adds new items to the GroupModelView:
if (split[0] == "group")
{
currentGroup = new GroupViewModel();
currentGroup.Name = split[1];
MainData.GroupModelList.Add(currentGroup);
}
I created a ListBox in my WPF application with these XAML options:
<Window x:Class="SoundManager.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vm="clr-namespace:SoundManager.ViewModels"
xmlns:vm2="clr-namespace:SoundManager.Code"
Title="MainWindow" Height="720" Width="1280">
<Window.Resources>
<vm:MainViewModel x:Key="MainViewModel" />
<vm2:MainData x:Key="MainData" />
</Window.Resources>
<ListBox Grid.Row="2" Height="484" HorizontalAlignment="Left" Margin="12,0,0,0" Name="lbFoundItems" VerticalAlignment="Top" Width="201" ItemsSource="{Binding Source={StaticResource MainData}, Path=GroupModelList/Name}" />
but for some reason the data isn't updating in the UI (new items aren't added visibly in the UI).
I've been just getting started with the MVVM pattern and databinding and I can't figure out what I'm doing wrong.
Thanks in advance!
GroupModelList/Name is not a valid property path here. Setting it like that does not make the ListBox show the Name property of the data items in the GroupModelList collection.
You would instead have to set the ListBox's DisplayMemberPath property:
<ListBox ItemsSource="{Binding Source={StaticResource MainData}, Path=GroupModelList}"
DisplayMemberPath="Name"/>
or set the ItemTemplate property:
<ListBox ItemsSource="{Binding Source={StaticResource MainData}, Path=GroupModelList}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Moreover, the GroupModelList property should not be static:
class MainData
{
private ObservableCollection<GroupViewModel> groupModelList =
new ObservableCollection<GroupViewModel>();
public ObservableCollection<GroupViewModel> GroupModelList
{
get { return groupModelList; }
}
}
Then you might have MainData as a property in your view model, and bind the ListBox like this:
<ListBox ItemsSource="{Binding Source={StaticResource MainViewModel},
Path=MainData.GroupModelList}" .../>
I am using the following XAML code to display a list of checked list boxes.
<ListBox x:Name="lbxProjects" ItemsSource="{Binding}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<ListBox x:Name="lbxUnits" ItemsSource="{Binding Units}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<CheckBox Content="{Binding unit.Name}" IsChecked="{Binding isSelected}"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The data model is as follows
public class ProjectsListBox
{
public Project project { get; set; }
public List<UnitsCheckBox> Units = new List<UnitsCheckBox>();
public ProjectsListBox(Project project)
{
this.project = project;
foreach(var d in project.Documents)
{
Units.Add(new UnitsCheckBox(d));
}
}
}
public class UnitsCheckBox : INotifyPropertyChanged
{
public Document unit { get; set; }
private bool isselected = true;
public bool isSelected
{
get { return isselected; }
set
{
isselected = value;
NotifyPropertyChanged("isSelected");
}
}
public UnitsCheckBox(Document d)
{
unit = d;
}
}
I am assigning the data source for the parent listbox like
lbxProjects.DataContext = projectsList;
The code creates the child list boxes but not the checkboxes inside the child list boxes. What am i missing?
How should WPF resolve unit.Name?
If the type UnitsCheckBox contains a Name property, then the CheckBox's Content should be bound to Name:
Content="{Binding Name}"
You should always specify the type of your DataTemplate:
<DataTemplate DataType="{x:Type local:UnitsCheckBox}" ...>
Those are the probable problems but I can't be sure unless you give us the UnitsCheckBox code.
I'm trying to code an rssreader and would be pleased for some architecture hints.
My reader main window hosts two wpf pages which are loaded into frames, it's a "bottombar" where user can select different rss providers. In the main frame (or page) is my listview.
Because of an loading animation and UI Freeze I've an extra class with a backgroundworker which fills an observable collection with RSS Data, when I'm debugging, it fills my collection correctly.
In main page i'm setting the datacontext to this observable collection but listview doesn't show anything, here I'm stuck.
That's what I have:
MainPage XAML:
> <ListBox ItemsSource="{Binding}" DisplayMemberPath="RssTitle"
> IsSynchronizedWithCurrentItem="True"
> SelectionChanged="itemsList_SelectionChanged"
> ItemContainerStyle="{DynamicResource listboxitem_style}" Height="396"
> HorizontalAlignment="Left" Margin="126,12,0,0" Name="ListBox1"
> VerticalAlignment="Top" Width="710"></ListBox>
ListBox1.DataContext = GetRssItems.observable_list;
Bottompage to get another rss feed:
GetRssItems getitems = new GetRssItems();
GetRssItems.observable_collection = null;
getitems.start_bg_worker("url");
GetRssItems.cs
public class GetRssItems
{
public static ObservableCollection<RSSItem> observable_collection { get; set; }
public static string tmp_url;
public BackgroundWorker worker = new BackgroundWorker();
public void start_bg_worker(string url)
{
if (!worker.IsBusy)
{
worker.DoWork += new DoWorkEventHandler(worker_DoWork);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
worker.RunWorkerAsync(url);
}
}
}
In BackgroundWorkers DoWork I'm receiving rss items with linq and add it to my observable collection:
observable_collection.Add(new RSSItem(item.tmp_Title, item.tmp_Link, item.tmp_Description, item.tmp_pubDate, item.tmp_ImageUrl));
Seperate class RSSItem.cs
public class RSSItem
{
public string RssTitle { get; set; }
public string RssLink { get; set; }
public string RssDescription { get; set; }
public string RsspubDate { get; set; }
public string RssImageUrl { get; set; }
public RSSItem(string rsstitle, string rsslink, string rssdescription, string rsspubdate, string rssimageurl)
{
RssTitle = rsstitle;
RssLink = rsslink;
RssDescription = rssdescription;
RsspubDate = rsspubdate;
RssImageUrl = rssimageurl;
}
}
Thanks for your time and hints.
Best Regards
You need to read up a bit MVVM to get the most benefit from WPF. Your line setting the listbox's datacontext is rather confusing.
What you should have is your main window's (xaml) data context set to a view model class that contains your observable collection. The list box's ItemsSource is set to that property name.
For example:
public class MainViewModel : INotifyPropertyChanged
{
public ObservableCollection<RSSItem> RSSItems
{
get;
set;
}
// Other stuff applicable to the main window.
}
When the view is constructed, pass an instance of the MainViewModel to it's DataContext. Then the Xaml for the ListBox would be:
<ListBox ItemsSource={Binding Path=RSSItems} ... />
If you want to be able to set/change the RSSItems collection instance (I.e. public setter) then you should set it up it's setter with the NotifyPropertyChanged event, however if you just add/remove items then this shouldn't be necessary. (I.e. loading populating the items in the constructor.)
use the following:
the data context should be the Object getitems
<ListBox ItemsSource="{Binding observable_collection}" Height="167" Margin="0" Name="listBox1" Width="330" FontSize="24" HorizontalAlignment="Center" VerticalAlignment="Top">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding RssTitle}" FontWeight="Bold" FontSize="16" />
<TextBlock Text="{Binding RssLink}" FontSize="16"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
PS:
your naming is HORRBILE