Make ObservableCollection item invisible - wpf

Question

This is my Model:
ObservableCollection<Student> StudentsList;
class Student
{
static ObservableCollection<Student> Students;
string SName;
String FName;
}
And i have simple Combobox:
<ComboBox
x:Name="cbStudents"
ItemsSource="{Binding StudentsList}">
I case i want to hide from my Combobox item/items, is it possible to do that without using the function Remove from my Students ObservableCollection ?
Edit:
After try mm8 solution it seems that my combo box style i cause my error so this is my style:
<!-- region combobox style -->
<SolidColorBrush x:Key="ComboBoxNormalBorderBrush" Color="Transparent" />
<SolidColorBrush x:Key="ComboBoxNormalBackgroundBrush" Color="#FF103766" />
<SolidColorBrush x:Key="ComboBoxDisabledForegroundBrush" Color="#888" />
<SolidColorBrush x:Key="ComboBoxDisabledBackgroundBrush" Color="#FF7AA0CD" />
<SolidColorBrush x:Key="ComboBoxDisabledBorderBrush" Color="#FF7AA0CD" />
<Style TargetType="{x:Type ComboBoxItem}">
<Setter Property="SnapsToDevicePixels" Value="true" />
<Setter Property="HorizontalAlignment" Value="Stretch" />
<Setter Property="VerticalAlignment" Value="Stretch" />
<Setter Property="OverridesDefaultStyle" Value="true"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBoxItem">
<Border
Name="Border"
Padding="5"
Margin="0"
BorderThickness="0"
CornerRadius="0"
Background="Transparent"
BorderBrush="Transparent" >
<TextBlock TextAlignment="Left">
<ContentPresenter />
</TextBlock>
</Border>
<ControlTemplate.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsMouseOver" Value="true"/>
<Condition Property="IsSelected" Value="false"/>
<Condition Property="IsHighlighted" Value="true"/>
</MultiTrigger.Conditions>
<Setter Property="Foreground" Value="White"/>
<Setter TargetName="Border" Property="BorderBrush" Value="#FF103766"/>
<Setter TargetName="Border" Property="Background" Value="#FF103766"/>
</MultiTrigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsMouseOver" Value="false"/>
<Condition Property="IsSelected" Value="true"/>
</MultiTrigger.Conditions>
<Setter Property="Foreground" Value="White"/>
<Setter TargetName="Border" Property="BorderBrush" Value="#FF103766"/>
<Setter TargetName="Border" Property="Background" Value="#FF103766"/>
</MultiTrigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsMouseOver" Value="true"/>
<Condition Property="IsSelected" Value="true"/>
</MultiTrigger.Conditions>
<Setter Property="Foreground" Value="White"/>
<Setter TargetName="Border" Property="BorderBrush" Value="#FF103766"/>
<Setter TargetName="Border" Property="Background" Value="#FF103766"/>
</MultiTrigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsMouseOver" Value="false"/>
<Condition Property="IsSelected" Value="false"/>
</MultiTrigger.Conditions>
<Setter Property="Foreground" Value="#FF103766"/>
<Setter TargetName="Border" Property="BorderBrush" Value="White"/>
<Setter TargetName="Border" Property="Background" Value="White"/>
</MultiTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<ControlTemplate TargetType="ToggleButton" x:Key="ComboBoxToggleButtonTemplate">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="20" />
</Grid.ColumnDefinitions>
<Border
Grid.ColumnSpan="2"
Name="Border"
BorderBrush="{StaticResource ComboBoxNormalBorderBrush}"
CornerRadius="0"
BorderThickness="1, 1, 1, 1"
Background="{StaticResource ComboBoxNormalBackgroundBrush}" />
<Border
Grid.Column="1"
Margin="1, 1, 1, 1"
BorderBrush="#444"
Name="ButtonBorder"
CornerRadius="0, 0, 0, 0"
BorderThickness="0, 0, 0, 0"
Background="{StaticResource ComboBoxNormalBackgroundBrush}" />
<Path
Name="Arrow"
Grid.Column="1"
Data="M 0 0 L 8 12 L 16 0 Z"
HorizontalAlignment="Center"
Fill="#444"
VerticalAlignment="Center"
Margin="-10,0,0,0"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="UIElement.IsMouseOver" Value="True">
<Setter Property="Panel.Background" TargetName="ButtonBorder" Value="Transparent"/>
<Setter Property="Shape.Fill" TargetName="Arrow" Value="White"/>
<Setter Property="Panel.Background" TargetName="Border" Value="#FF7AA0CD"/>
</Trigger>
<Trigger Property="UIElement.IsMouseOver" Value="False">
<Setter Property="Shape.Fill" TargetName="Arrow" Value="Transparent"/>
</Trigger>
<Trigger Property="ToggleButton.IsChecked" Value="True">
<Setter Property="Panel.Background" TargetName="ButtonBorder" Value="Transparent"/>
<Setter Property="Shape.Fill" TargetName="Arrow" Value="White"/>
</Trigger>
<Trigger Property="UIElement.IsEnabled" Value="False">
<Setter Property="Panel.Background" TargetName="Border" Value="{StaticResource ComboBoxDisabledBackgroundBrush}"/>
<Setter Property="Panel.Background" TargetName="ButtonBorder" Value="{StaticResource ComboBoxDisabledBackgroundBrush}"/>
<Setter Property="Border.BorderBrush" TargetName="ButtonBorder" Value="{StaticResource ComboBoxDisabledBorderBrush}"/>
<Setter Property="TextElement.Foreground" Value="{StaticResource ComboBoxDisabledForegroundBrush}"/>
<Setter Property="Shape.Fill" TargetName="Arrow" Value="Transparent"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
<Style x:Key="ComboBoxFlatStyle" TargetType="{x:Type ComboBox}">
<Setter Property="UIElement.SnapsToDevicePixels" Value="True"/>
<Setter Property="FrameworkElement.OverridesDefaultStyle" Value="True"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.CanContentScroll" Value="True"/>
<Setter Property="TextElement.Foreground" Value="Gainsboro"/>
<Setter Property="FrameworkElement.FocusVisualStyle" Value="{x:Null}"/>
<Setter Property="Control.Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBox">
<Grid>
<ToggleButton
Name="ToggleButton"
Grid.Column="2"
ClickMode="Press"
Focusable="False"
IsChecked="{Binding Path=IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}, Mode=TwoWay}"
Template="{StaticResource ComboBoxToggleButtonTemplate}"/>
<ContentPresenter
Name="ContentSite"
Margin="5, 4, 23, 3"
IsHitTestVisible="False"
HorizontalAlignment="Left"
VerticalAlignment="Center"
Content="{TemplateBinding ComboBox.SelectionBoxItem}"
ContentTemplate="{TemplateBinding ComboBox.SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"/>
<TextBox
Name="PART_EditableTextBox"
Margin="3, 3, 23, 3"
IsReadOnly="{TemplateBinding IsReadOnly}"
Visibility="Hidden"
Background="Transparent"
HorizontalAlignment="Left"
VerticalAlignment="Center"
Focusable="True" >
<TextBox.Template>
<ControlTemplate TargetType="TextBox" >
<Border Name="PART_ContentHost" Focusable="False" />
</ControlTemplate>
</TextBox.Template>
</TextBox>
<Popup
Name="Popup"
Placement="Bottom"
Focusable="False"
AllowsTransparency="True"
IsOpen="{TemplateBinding ComboBox.IsDropDownOpen}"
PopupAnimation="Fade">
<Grid
Name="DropDown"
SnapsToDevicePixels="True"
MinWidth="{TemplateBinding FrameworkElement.ActualWidth}"
MaxHeight="{TemplateBinding ComboBox.MaxDropDownHeight}">
<Border
Name="DropDownBorder"
Background="Gainsboro"
Margin="0, 0, 0, 0"
CornerRadius="0"
BorderBrush="#FF103766"
BorderThickness="1" />
<ScrollViewer Margin="4" SnapsToDevicePixels="True">
<ItemsPresenter KeyboardNavigation.DirectionalNavigation="Contained" />
</ScrollViewer>
</Grid>
</Popup>
<!-- Popup showing items -->
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="UIElement.IsMouseOver" Value="True">
<Setter Property="TextElement.Foreground" Value="White"/>
</Trigger>
<Trigger Property="UIElement.IsMouseOver" Value="False">
<Setter Property="TextElement.Foreground" Value="Gainsboro"/>
</Trigger>
<Trigger Property="ItemsControl.HasItems" Value="False">
<Setter Property="FrameworkElement.MinHeight" TargetName="DropDownBorder" Value="95"/>
</Trigger>
<Trigger Property="UIElement.IsEnabled" Value="False">
<Setter Property="TextElement.Foreground" Value="Gainsboro"/>
</Trigger>
<Trigger Property="ItemsControl.IsGrouping" Value="True">
<Setter Property="ScrollViewer.CanContentScroll" Value="False"/>
</Trigger>
<Trigger Property="ComboBox.IsEditable" Value="True">
<Setter Property="KeyboardNavigation.IsTabStop" Value="False"/>
<Setter Property="UIElement.Visibility" TargetName="PART_EditableTextBox" Value="Visible"/>
<Setter Property="UIElement.Visibility" TargetName="ContentSite" Value="Hidden"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<!-- endregion of Flat ComboBox -->

Answer 1

You could use an ItemContainerStyle with a DataTrigger to for example hide a Student with a particular name, e.g.:
<ComboBox
x:Name="cbStudents"
ItemsSource="{Binding StudentsList}">
<ComboBox.ItemContainerStyle>
<Style TargetType="ComboBoxItem">
<Style.Triggers>
<DataTrigger Binding="{Binding SName}" Value="SomeName">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
</ComboBox.ItemContainerStyle>
</ComboBox>
Edit: (see the comments below) "ComboBoxFlatStyle" is a ComboBox style. The ItemContainerStyle should be based on the implicit ComboBoxItem style:
<ComboBox Style="{StaticResource ComboBoxFlatStyle}" ...>
<ComboBox.ItemContainerStyle>
<Style TargetType="ComboBoxItem" BasedOn="{StaticResource {x:Type ComboBoxItem}}">
...
</Style>
</ComboBox.ItemContainerStyle>
</ComboBox>

Answer 2

you need CollectionViewSource and filter delegate
#region feed items
private ObservableCollection<OpdsItemBase> _FeedItems = new ObservableCollection<OpdsItemBase>();
public ICollectionView FeedItemView
{
get
{
return CollectionViewSource.GetDefaultView(_FeedItems);
}
}
#endregion
and
public string FilterText
{
get { return _filterText; }
set
{
_filterText = value;
FeedItemView.Filter = delegate(object obj)
{
if (string.IsNullOrEmpty(_filterText))
return true;
OpdsItemBase data = obj as OpdsItemBase;
if (data == null)
return false;
return (data.Title.IndexOf(_filterText, 0, StringComparison.InvariantCultureIgnoreCase) > -1);
};
}
}