Regroupement par valeur de propriété à l'aide de LINQ

Question

Je voulais créer un LongListSelector contrôle dans lequel les valeurs sont regroupées en plusieurs catégories.Chaque élément a ces propriétés :

Public Class SideItem
  Private _Title As String
  Public Property Title As String
    Get
        Return _Title
    End Get
    Set(value As String)
        _Title = value
    End Set
  End Property

  Private _Icon As System.Windows.Shapes.Path
  Public Property Icon As System.Windows.Shapes.Path
    Get
        Return _Icon
    End Get
    Set(value As System.Windows.Shapes.Path)
        _Icon = value
    End Set
  End Property

  Private _Category As String
  Public Property Category As String
    Get
        Return _Category
    End Get
    Set(value As String)
        _Category = value
    End Set
  End Property

  Private _NavigationUri As Uri
  Public Property NavigationUri As Uri
    Get
        Return _NavigationUri
    End Get
    Set(value As Uri)
        _NavigationUri = value
    End Set
  End Property
End Class

J'aimerais regrouper une liste de SideItem en fonction de la valeur de Category propriété.J'ai regardé plusieurs exemples mais je n'ai pas réussi à le faire.C'est ma dernière tentative (parmi plusieurs)

Me.Items = (From data In L
             Group data By Key = New With {Key data.Category} Into Group
             Select New SideItem With {
                 .Category = Key.Category, _
                 .Title = Group.Select(Function(itm As SideItem) itm.Title), _
                 .Icon = Group.Select(Function(itm As SideItem) itm.Icon), _
                 .NavigationUri = Group.Select(Function(itm As SideItem) itm.NavigationUri)
             }).OfType(Of SideItem)()

MISE À JOUR:SOLUTION

J'ai utilisé le code que vous pouvez trouver dans la réponse de Verdesrobert, voté comme le meilleur, mais j'ai édité le AlphaKeyGroup cours afin de répondre à mes besoins.

Public Class AlphaKeyGroup(Of T)
Inherits List(Of T)
Public Delegate Function GetKeyDelegate(item As T) As String

Public Property Key() As String
    Get
        Return m_Key
    End Get
    Private Set(value As String)
        m_Key = value
    End Set
End Property
Private m_Key As String

Public Sub New(key__1 As String)
    Key = key__1
End Sub
Private Shared Function CreateGroups(slg As List(Of String)) As List(Of AlphaKeyGroup(Of T))
    Dim list As New List(Of AlphaKeyGroup(Of T))()

    For Each key As String In slg
        list.Add(New AlphaKeyGroup(Of T)(key))
    Next
    Return list
End Function

Public Shared Function CreateGroups(items As IEnumerable(Of T), ci As CultureInfo, getKey As GetKeyDelegate, sort As Boolean) As List(Of AlphaKeyGroup(Of T))
    Dim headerList As New List(Of String)
    For Each header As T In items
        headerList.Add(getKey(header))
    Next
    Dim list As List(Of AlphaKeyGroup(Of T)) = CreateGroups(headerList)

    For Each item As T In items
        list(list.IndexOf(list.Where(Function(I As AlphaKeyGroup(Of T)) I.Key = getKey(item)).First)).Add(item)
    Next

    If sort Then
        For Each group As AlphaKeyGroup(Of T) In list
            group.Sort(Function(c0, c1)
                           Return ci.CompareInfo.Compare(getKey(c0), getKey(c1))
                       End Function)
        Next
    End If
    Return list
End Function

Fin du cours

Answer 1

Vous avez d’abord besoin d’une classe qui fournit une structure de liste groupée :

    Public Class AlphaKeyGroup(Of T)
    Inherits List(Of T)
    Public Delegate Function GetKeyDelegate(item As T) As String

    Public Property Key() As String
        Get
            Return m_Key
        End Get
        Private Set
            m_Key = Value
        End Set
    End Property
    Private m_Key As String

    Public Sub New(key__1 As String)
        Key = key__1
    End Sub
    Private Shared Function CreateGroups(slg As SortedLocaleGrouping) As List(Of AlphaKeyGroup(Of T))
        Dim list As New List(Of AlphaKeyGroup(Of T))()

        For Each key As String In slg.GroupDisplayNames
            list.Add(New AlphaKeyGroup(Of T)(key))
        Next
        Return list
    End Function

    Public Shared Function CreateGroups(items As IEnumerable(Of T), ci As CultureInfo, getKey As GetKeyDelegate, sort As Boolean) As List(Of AlphaKeyGroup(Of T))
        Dim slg As New SortedLocaleGrouping(ci)
        Dim list As List(Of AlphaKeyGroup(Of T)) = CreateGroups(slg)

        For Each item As T In items
            Dim index As Integer = 0
            index = slg.GetGroupIndex(getKey(item))
            If index >= 0 AndAlso index < list.Count Then
                list(index).Add(item)
            End If
        Next

        If sort Then
            For Each group As AlphaKeyGroup(Of T) In list
                group.Sort(Function(c0, c1) 
                Return ci.CompareInfo.Compare(getKey(c0), getKey(c1)) 
                          End Function)
            Next
        End If
        Return list
    End Function
End Class

En utilisant votre classe SideItem, vous devez ensuite créer une liste de SideItem :

// Your code to provide the list of items like this:
Dim source As New List(Of SideItem)()
//add data to the list or skip the creation and provide your data 

Regroupez ensuite la liste comme ceci :

List<AlphaKeyGroup<SideItem>> DataSource = AlphaKeyGroup<SideItem>.CreateGroups(source, 
            System.Threading.Thread.CurrentThread.CurrentUICulture,
            (SideItem s) => { return s.Category; }, true);

Lier au LongListSelector ItemsSource :

Me.ItemsSource = DataSource;

LongListSelector XAML :

<phone:LongListSelector
    x:Name="Me"
    JumpListStyle="{StaticResource SideItemJumpListStyle}"
    Background="Transparent"
    GroupHeaderTemplate="{StaticResource SideItemGroupHeaderTemplate}"
    ItemTemplate="{StaticResource SideItemItemTemplate}"
    LayoutMode="List"
    IsGroupingEnabled="true"
    HideEmptyGroups ="true"/>

Modèle d'élément XAML :

<DataTemplate x:Key="SideItemItemTemplate">
   <StackPanel VerticalAlignment="Top">
      <TextBlock FontWeight="Bold"  Text="{Binding Title}" />
   </StackPanel>
</DataTemplate>

GroupHeaderTemplate XAML :

<DataTemplate x:Key="SideItemGroupHeaderTemplate">
   <Border Background="Transparent" Padding="5">
      <Border Background="{StaticResource PhoneAccentBrush}" BorderBrush="{StaticResource PhoneAccentBrush}" BorderThickness="2" Width="62" 
         Height="62" Margin="0,0,18,0" HorizontalAlignment="Left">
         <TextBlock Text="{Binding Key}" Foreground="{StaticResource PhoneForegroundBrush}" FontSize="48" Padding="6" 
            FontFamily="{StaticResource PhoneFontFamilySemiLight}" HorizontalAlignment="Left" VerticalAlignment="Center"/>
      </Border>
   </Border>
</DataTemplate>

Style de liste de saut XAML :

    <phone:JumpListItemBackgroundConverter x:Key="BackgroundConverter"/>
    <phone:JumpListItemForegroundConverter x:Key="ForegroundConverter"/>
    <Style x:Key="SideItemJumpListStyle" TargetType="phone:LongListSelector">
        <Setter Property="GridCellSize"  Value="113,113"/>
        <Setter Property="LayoutMode" Value="Grid" />
        <Setter Property="ItemTemplate">
            <Setter.Value>
                <DataTemplate>
                    <Border Background="{Binding Converter={StaticResource BackgroundConverter}}" Width="113" Height="113" Margin="6" >
                        <TextBlock Text="{Binding Key}" FontFamily="{StaticResource PhoneFontFamilySemiBold}" FontSize="48" Padding="6" 
           Foreground="{Binding Converter={StaticResource ForegroundConverter}}" VerticalAlignment="Center"/>
                    </Border>
                </DataTemplate>
            </Setter.Value>
        </Setter>
    </Style>

Cela devrait suffire.

Réponse basée sur http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj244365(v=vs.105).aspx