I have a table of categories in my database, as below.
Category
categoryId
name
parentId
The parentId links back to itself to form hierarchy.
How do I bind it to a combobox in WPF so that the child elements are indented as appropriate for each level?
XAML:
<ComboBox ItemsSource="{Binding YourItems}">
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock Margin="{Binding Level, Converter={x:Static my:MainWindow.LevelToMarginConverter}}" Text="{Binding Name}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
C#:
class MainWindow {
......
class LevelToMarginConverterClass : IValueConverter {
const int onelevelmargin = 10;
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) {
int level = (int)value;
return new Thickness(level * onelevelmargin,0,0,0);
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) {
return null;
}
}
public static IValueConverter LevelToMarginConverter = new LevelToMarginConverterClass();
}
Be sure to have int Level and string Name properties in your class
Related
I have a DataTemplate of an acollectionView, inside I have a Label with the Text in Binding property.
<CollectionView.ItemTemplate>
<DataTemplate>
<Grid BackgroundColor="Gray" Opacity="0.8" RowSpacing="0.1">
<Label TextColor="White" Text="{Binding Data}"/>
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
I would need to be able to split that string into multiple strings, and I was able to find this code
public class DelimiterConverter : IValueConverter
{
public object Convert(Object value, Type targetType, object parameter, CultureInfo culture)
{
string[] values = ((string)value).Split(' ');
int index = int.Parse((string)parameter);
return values[index];
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return "";
}
}
HumorDiary[] note = JsonConvert.DeserializeObject<HumorDiary[]>(textt);
DelimiterConverter conv = new DelimiterConverter();
foreach (HumorDiary hd in note)
{
conv.Convert(hd.Data, typeof(string), " ", CultureInfo.CurrentCulture);
}
I don't know if I have entered everything right, but I would not know how to obtain the various strings divided into several parts, in the DataTemplate
It could be used like this:
Add the namespace where your converter is to you page
xmlns:converters="clr-namespace:MyApp.Converters"
Add the converter to your page's resources
<ContentPage.Resources>
<converters:StringSplitConverter x:Key="StringSplitConverter" />
</ContentPage.Resources>
Edit the CollectionView's ItemTemplate to display all the separated strings in separate labels (using BindableLayout)
<CollectionView.ItemTemplate>
<DataTemplate>
<Grid BackgroundColor="Gray" Opacity="0.8" RowSpacing="0.1">
<!-- Bind the ItemsSource to the Data using the converter -->
<StackLayout BindableLayout.ItemsSource="{Binding Data, Converter={StaticResource StringSplitConverter}}">
<BindableLayout.ItemTemplate>
<DataTemplate>
<!-- Display the separated word -->
<Label Text="{Binding .}" />
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout>
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
This is the converter. Takes the string and splits it by spaces
public class StringSplitConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is string stringValue)
{
return stringValue.Split(' ');
}
return value;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
I need access to the entry component that the converter is attached to, so I can change the cursor position with Entry.CursorPosition.
I have a BindableObject that is also an IValueConverter, how can I get to the Entry
public class MaskConverter : BindableObject, IValueConverter
{
...
}
In XAML name the Entry and use x:Reference:
Converter with MyEntry property (ConvertBack for Mode=TwoWay not shown):
public class MyConverter : BindableObject, IValueConverter
{
public Entry MyEntry { get; set; }
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var entry = MyEntry;
Debug.WriteLine($"convert:pos:{entry?.CursorPosition}:");
return (string)value;
}
...
}
XAML using MyEntry property (MyText is a property on the viewmodel, not shown):
<ContentPage.Resources>
<local:MyConverter x:Key="myConverter" MyEntry="{x:Reference myEntry}" />
...
</ContentPage.Resources>
...
<Entry x:Name="myEntry" Text="{Binding MyText,
Converter={StaticResource myConverter}}">
Without the MyEntry property the named Entry might be passed to the converter using ConverterParameter:
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var param = parameter as Entry;
Debug.WriteLine($"convert:pos:{param?.CursorPosition}:");
return (string)value;
}
XAML when passing the named Entry in ConverterParameter:
<ContentPage.Resources>
<local:MyConverter x:Key="myConverter" />
...
</ContentPage.Resources>
...
<Entry x:Name="myEntry" Text="{Binding MyText,
Converter={StaticResource myConverter},
ConverterParameter={x:Reference myEntry}}">
Using a wpf ListBox I'm trying to display a list of filename without displaying the full path (more convenient for user).
Data comes from an ObservableCollection which is filled using Dialog.
private ObservableCollection<string> _VidFileDisplay = new ObservableCollection<string>(new[] {""});
public ObservableCollection<string> VidFileDisplay
{
get { return _VidFileDisplay; }
set { _VidFileDisplay = value; }
}
In the end I want to select some items and get back the full file path. For this I have a converter :
public class PathToFilenameConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
//return Path.GetFileName(value.ToString());
string result = null;
if (value != null)
{
var path = value.ToString();
if (string.IsNullOrWhiteSpace(path) == false)
result = Path.GetFileName(path);
}
return result;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return value;
}
}
Which I bind to my listbox itemsource :
<ListBox x:Name="VideoFileList" Margin="0" Grid.Row="1" Grid.RowSpan="5" Template="{DynamicResource BaseListBoxControlStyle}" ItemContainerStyle="{DynamicResource BaseListBoxItemStyle}" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ItemsSource="{Binding Path=DataContext.VidFileDisplay, Converter={StaticResource PathToFileName},ElementName=Ch_Parameters, Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" SelectedItem="{Binding Path=SelectedVidNames,ElementName=Ch_Parameters, Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}">
Without the converter, it is working fine (but of course this is the full path displayed in the listbox). With the converter I have one character per line... displaying this :
System.Collections.ObjectModel.ObservableCollection`1[System.String]
Where am I wrong ?
Thank you
In ItemsSource binding converter applies to the whole list and not to each item in the collection. If you want to apply your converter per item you need to do it ItemTemplate
<ListBox x:Name="VideoFileList" ItemsSource="{Binding Path=DataContext.VidFileDisplay, ElementName=Ch_Parameters}" ...>
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=., Converter={StaticResource PathToFileName}}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
class EnumToStringConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, string language)
{
return loai.ToDisplaytring();
}
public object ConvertBack(object value, Type targetType, object parameter, string language)
{
throw new NotImplementedException();
}
}
<ListView ItemsSource="{Binding ListEnum" Margin="0,51,0,0">
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=.,Converter={StaticResource EnumToStringConverter}}" HorizontalAlignment="Center" FontSize="18"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
I am a new guy to XAML.
I just want to display enum in listview.
But it has some problem of binding itself with binding:
{Binding Path=.,Converter={StaticResource EnumToStringConverter}}
This is simpler:
<ListView x:Name="ListViewInstance" ItemsSource="{Binding ListEnum}" Margin="0,51,0,0">
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" HorizontalAlignment="Center" FontSize="18"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
That's the binding that gets the items, it automatically makes the item.ToString()
and to show all the values in the DataContext, for instance:
public List<Devices> ListEnum { get { return typeof(Devices).GetEnumValues().Cast<Devices>().ToList(); } }
In case you need a converter do the following:
public class EnumToStringConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return what you need to convert from value
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
and then in XAML
<Window.Resources>
<local:EnumToStringConverter x:Key="EnumToStringConverter"/>
</Window.Resources>
<ListView x:Name="ListViewInstance" ItemsSource="{Binding ListEnum}" Margin="0,51,0,0">
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding, Converter={StaticResource EnumToStringConverter}}" HorizontalAlignment="Center" FontSize="18"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
You can use the enum with attributes and the create a list for listbox using extension methods.You can refer the below code.
<ListBox Width="200" Height="25" ItemsSource="{Binding ComboSource}"
DisplayMemberPath="Value"
SelectedValuePath="Key"/>
public class MainViewModel
{
public List<KeyValuePair<RentStatus, string>> ComboSource { get; set; }
public MainViewModel()
{
ComboSource = new List<KeyValuePair<RentStatus, string>>();
RentStatus re=RentStatus.Active;
ComboSource = re.GetValuesForComboBox<RentStatus>();
}
}
public enum RentStatus
{
[Description("Preparation description")]
Preparation,
[Description("Active description")]
Active,
[Description("Rented to people")]
Rented
}
public static class ExtensionMethods
{
public static List<KeyValuePair<T, string>> GetValuesForComboBox<T>(this Enum theEnum)
{
List<KeyValuePair<T, string>> _comboBoxItemSource = null;
if (_comboBoxItemSource == null)
{
_comboBoxItemSource = new List<KeyValuePair<T, string>>();
foreach (T level in Enum.GetValues(typeof(T)))
{
string Description = string.Empty;
FieldInfo fieldInfo = level.GetType().GetField(level.ToString());
DescriptionAttribute[] attributes = (DescriptionAttribute[])fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attributes != null && attributes.Length > 0)
{
Description = attributes.FirstOrDefault().Description;
}
KeyValuePair<T, string> TypeKeyValue = new KeyValuePair<T, string>(level, Description);
_comboBoxItemSource.Add(TypeKeyValue);
}
}
return _comboBoxItemSource;
}
}
I have an object with this structure
public class Parent
{
public string Name {get; set;}
public int ID {get; set;}
public List<Child> Children{set; get;}
public Address HomeAddress {get; set;}
}
I created a hierarchical template for Address, Parent, Children with the ObjectToObservableListConverter
public class ObjectToObservableListConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value != null)
{
return new ObservableCollection<Graphic> { (value as Graphic) };
}
return null;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
and PropertyToListConverter
public class PropertyToListConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
Type type = value.GetType();
PropertyInfo[] propertyList = value.GetType().GetProperties();
List<object> values =
(from property in propertyList
//where property.GetCustomAttributes(typeof(NotForTreeViewAttribute), false).Count() == 0
select property.GetValue(value, BindingFlags.Default, null, null, CultureInfo.InvariantCulture)).ToList();
return values;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
The templates I created are:
<TreeView ItemsSource="{Binding Path=Parent,
Converter={StaticResource ResourceKey=objectToListConverter},
UpdateSourceTrigger=PropertyChanged}">
<TreeView.Resources>
<HierarchicalDataTemplate DataType="{x:Type en:Parent}"
ItemsSource="{Binding Path=Children}">
<StackPanel Orientation="Horizontal">
<TextBlock Margin="0,4,0,0"
VerticalAlignment="Center"
FontWeight="Bold"
Text="Children" />
</StackPanel>
</HierarchicalDataTemplate>
<HierarchicalDataTemplate DataType="{x:Type en:Child}"
ItemsSource="{Binding Converter={StaticResource ResourceKey=propertyToListConvertor}}">
<StackPanel Orientation="Horizontal">
<TextBlock Margin="0,4,0,0"
VerticalAlignment="Center"
FontWeight="Bold"
Text="{Binding Path=ChildName}" />
</StackPanel>
</HierarchicalDataTemplate>
<HierarchicalDataTemplate DataType="{x:Type en:Address}"
ItemsSource="{Binding Converter={StaticResource ResourceKey=propertyToListConvertor}}">
<StackPanel Orientation="Horizontal">
<TextBlock Margin="0,4,0,0"
VerticalAlignment="Center"
FontWeight="Bold"
Text="AddressType" />
</StackPanel>
</HierarchicalDataTemplate>
</TreeView.Resources>
</TreeView>
If I create the template on Parent
and set the ItemsSource Path of the Children Property, I don't Get the remaining properties of Parent.
Or
If I set the ItemsSource as the property of type Parent and user property to list converter i dont get hierarchy of children.
What am I missing?
Please help. Thanks in Advance
I found the solution to the problem.
I changed my converter to set the list property to another custom class which contains only one property of list type and wrote a hierarchical data template for the same.
PropertyToListConverter
public class PropertyToListConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
Type type = value.GetType();
PropertyInfo[] propertyList = value.GetType().GetProperties();
List<object> values =
(from property in propertyList
select GetValueOrElementName(value, property)).ToList();
return values;
}
private static object GetValueOrElementName(object value, PropertyInfo property)
{
var propVal = property.GetValue(value, BindingFlags.Default, null, null, CultureInfo.InvariantCulture);
if (property.PropertyType.IsGenericType && propVal != null)
{
Type type = property.PropertyType.GetGenericArguments().FirstOrDefault();
if (type == typeof(Child))
return new EnumerableClass() { Children = propVal as List<Child> };
}
if (propVal != null && !string.IsNullOrEmpty(propVal.ToString()))
return propVal;
return "Property["+ property.Name+"]";
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
CustomClass
public class EnumerableClass
{
public string Name { get; set; }
public List<Child> Children
{
get;
set;
}
}
Hierarchical Data template
<HierarchicalDataTemplate DataType="{x:Type en:Parent}"
ItemsSource="{Binding Converter={StaticResource ResourceKey=propertyToListConvertor}}">
<StackPanel Orientation="Horizontal">
<TextBlock Margin="0,4,0,0"
VerticalAlignment="Center"
FontWeight="Bold"
Text="{Binding Path=ParentName}" />
</StackPanel>
</HierarchicalDataTemplate>
<HierarchicalDataTemplate DataType="{x:Type ap:EnumerableClass}"
ItemsSource="{Binding Path=Children,UpdateSourceTrigger=PropertyChanged}">
<StackPanel Orientation="Horizontal">
<TextBlock Margin="0,4,0,0"
VerticalAlignment="Center"
FontWeight="Bold"
Text="Children" />
</StackPanel>
</HierarchicalDataTemplate>