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Categorieën > VB.NET

Sorteren Datagridview op binded List(Of T) (Opgelost)

Ontani - 04/02/2011 16:43

-1

Ik heb een datagridview met z'n datasource als List(Of T). Ik zou de kolommen willen sorteren en mogelijk op elke mogelijke property van BlogPost.

vbnet code - Bekijk de code zonder highlighting - Klap code in

                'Database access : items = List(BlogPost)
dgBlogPosts.DataSource = items

'My BlogPost Class
Public Class BlogPost

    Public Property ID As Integer
    Public Property Title As String
    Public Property Content As String
    Public Property CreationDate As DateTime
    Public Property Rating As Decimal = 5.0

End Class

            
'Database access : items = List(BlogPost)
dgBlogPosts.DataSource = items
 
'My BlogPost Class
Public Class BlogPost
 
    Public Property ID As Integer
    Public Property Title As String
    Public Property Content As String
    Public Property CreationDate As DateTime
    Public Property Rating As Decimal = 5.0
 
End Class
 

4 antwoorden

Gesponsorde links

Abbas - 04/02/2011 17:24
Crew .NET		Kan je niet met een lambda-expressie de list sorteren op een property van die list? Bijvoorbeeld: csharp code - Bekijk de code zonder highlighting - Klap code in items = items.OrderBy(item => item.Title); items = items.OrderBy(item => item.Title); En dan terug toewijzen aan de DataGridView.

Ontani - 04/02/2011 22:44
-1		Net geprobeerd, het is doenbaar op die manier, maar dat wilt zeggen da ik voor elke datagrid waarin ik die objecten wil sorteren functies moet gaan schrijven voor de columHeaders klikbaar te maken. Aan de hand van de columnIndex ga kijken op welke property van m'n class ik moet gaan sorteren en aan de hand van de propertyType dan ook nog eens naar het juiste type moet gaan casten want OrderBy verwacht een Type parameter: OrderBy(Of Decimal) als het om een Decimal property gaat. En gaat natuurlijk niet werken als ik op een String Column klik.

Abbas - 04/02/2011 23:09
Crew .NET		Toen ik m'n reactie las, zag ik ook meteen dit probleem. Maar ik dek dat er een manier moet zijn om dit te kunnen doen. Ik ga me der seffes is achter zetten!

Ontani - 07/02/2011 12:01

-1

Opgelost met een tip op stackoverflow.

eerst : Database access : items = List(Of BlogPost)
nu : Database access : items = ProfelSortableList(Of BlogPost)

vb.net code - Bekijk de code zonder highlighting - Klap code in

Imports System.ComponentModel
Imports System.Linq.Expressions

Namespace ProfelFramework.Common

    Public Class ProfelSortableList(Of T)
        Inherits System.ComponentModel.BindingList(Of T)

        Private originalList As List(Of T)
        Private sortDirection As ListSortDirection
        Private sortProperty As PropertyDescriptor

        Private populateBaseList As Action(Of ProfelSortableList(Of T), List(Of T)) = Sub(a, b) a.ResetItems(b)

        Shared cachedOrderByExpressions As New Dictionary(Of String, Func(Of List(Of T), IEnumerable(Of T)))()

        Protected Overrides ReadOnly Property SupportsSortingCore() As Boolean
            Get
                Return True
            End Get
        End Property

        Protected Overrides ReadOnly Property SortDirectionCore() As ListSortDirection
            Get
                Return sortDirection
            End Get
        End Property

        Protected Overrides ReadOnly Property SortPropertyCore() As PropertyDescriptor
            Get
                Return sortProperty
            End Get
        End Property

        Public Sub New()
            originalList = New List(Of T)()
        End Sub

        Public Sub New(ByVal enumerable As IEnumerable(Of T))
            originalList = enumerable.ToList()
            populateBaseList(Me, originalList)
        End Sub

        Public Sub New(ByVal list As List(Of T))
            originalList = list
            populateBaseList(Me, originalList)
        End Sub

        Protected Overrides Sub ApplySortCore(ByVal prop As PropertyDescriptor, ByVal direction As ListSortDirection)
            sortProperty = prop

            Dim orderByMethodName = If(sortDirection = ListSortDirection.Ascending, "OrderBy", "OrderByDescending")
            Dim cacheKey = Convert.ToString(GetType(T).GUID.ToString & prop.Name) & orderByMethodName

            If Not cachedOrderByExpressions.ContainsKey(cacheKey) Then
                CreateOrderByMethod(prop, orderByMethodName, cacheKey)
            End If

            ResetItems(cachedOrderByExpressions(cacheKey)(originalList).ToList())
            ResetBindings()
            sortDirection = If(sortDirection = ListSortDirection.Ascending, ListSortDirection.Descending, ListSortDirection.Ascending)
        End Sub

        Private Sub CreateOrderByMethod(ByVal prop As PropertyDescriptor, ByVal orderByMethodName As String, ByVal cacheKey As String)
            Dim sourceParameter = Expression.Parameter(GetType(List(Of T)), "source")
            Dim lambdaParameter = Expression.Parameter(GetType(T), "lambdaParameter")
            Dim accesedMember = GetType(T).GetProperty(prop.Name)
            Dim propertySelectorLambda = Expression.Lambda(Expression.MakeMemberAccess(lambdaParameter, accesedMember), lambdaParameter)
            Dim orderByMethod = GetType(Enumerable).GetMethods().Where(Function(a) a.Name = orderByMethodName AndAlso a.GetParameters().Length = 2).[Single]().MakeGenericMethod(GetType(T), prop.PropertyType)

            Dim orderByExpression = Expression.Lambda(Of Func(Of List(Of T), IEnumerable(Of T)))(Expression.[Call](orderByMethod, New Expression() {sourceParameter, propertySelectorLambda}), sourceParameter)

            cachedOrderByExpressions.Add(cacheKey, orderByExpression.Compile())
        End Sub

        Protected Overrides Sub RemoveSortCore()
            ResetItems(originalList)
        End Sub

        Private Sub ResetItems(ByVal items As List(Of T))
            MyBase.ClearItems()

            For i As Integer = 0 To items.Count - 1
                MyBase.InsertItem(i, items(i))
            Next
        End Sub

        Protected Overrides Sub OnListChanged(ByVal e As ListChangedEventArgs)
            originalList = MyBase.Items.ToList()
        End Sub

    End Class

End Namespace

Imports System.ComponentModel
Imports System.Linq.Expressions
 
Namespace ProfelFramework.Common
 
    Public Class ProfelSortableList(Of T)
        Inherits System.ComponentModel.BindingList(Of T)
 
        Private originalList As List(Of T)
        Private sortDirection As ListSortDirection
        Private sortProperty As PropertyDescriptor
 
        Private populateBaseList As Action(Of ProfelSortableList(Of T), List(Of T)) = Sub(a, b) a.ResetItems(b)
 
        Shared cachedOrderByExpressions As New Dictionary(Of String, Func(Of List(Of T), IEnumerable(Of T)))()
 
        Protected Overrides ReadOnly Property SupportsSortingCore() As Boolean
            Get
                Return True
            End Get
        End Property
 
        Protected Overrides ReadOnly Property SortDirectionCore() As ListSortDirection
            Get
                Return sortDirection
            End Get
        End Property
 
        Protected Overrides ReadOnly Property SortPropertyCore() As PropertyDescriptor
            Get
                Return sortProperty
            End Get
        End Property
 
        Public Sub New()
            originalList = New List(Of T)()
        End Sub
 
        Public Sub New(ByVal enumerable As IEnumerable(Of T))
            originalList = enumerable.ToList()
            populateBaseList(Me, originalList)
        End Sub
 
        Public Sub New(ByVal list As List(Of T))
            originalList = list
            populateBaseList(Me, originalList)
        End Sub
 
        Protected Overrides Sub ApplySortCore(ByVal prop As PropertyDescriptor, ByVal direction As ListSortDirection)
            sortProperty = prop
 
            Dim orderByMethodName = If(sortDirection = ListSortDirection.Ascending, "OrderBy", "OrderByDescending")
            Dim cacheKey = Convert.ToString(GetType(T).GUID.ToString & prop.Name) & orderByMethodName
 
            If Not cachedOrderByExpressions.ContainsKey(cacheKey) Then
                CreateOrderByMethod(prop, orderByMethodName, cacheKey)
            End If
 
            ResetItems(cachedOrderByExpressions(cacheKey)(originalList).ToList())
            ResetBindings()
            sortDirection = If(sortDirection = ListSortDirection.Ascending, ListSortDirection.Descending, ListSortDirection.Ascending)
        End Sub
 
        Private Sub CreateOrderByMethod(ByVal prop As PropertyDescriptor, ByVal orderByMethodName As String, ByVal cacheKey As String)
            Dim sourceParameter = Expression.Parameter(GetType(List(Of T)), "source")
            Dim lambdaParameter = Expression.Parameter(GetType(T), "lambdaParameter")
            Dim accesedMember = GetType(T).GetProperty(prop.Name)
            Dim propertySelectorLambda = Expression.Lambda(Expression.MakeMemberAccess(lambdaParameter, accesedMember), lambdaParameter)
            Dim orderByMethod = GetType(Enumerable).GetMethods().Where(Function(a) a.Name = orderByMethodName AndAlso a.GetParameters().Length = 2).[Single]().MakeGenericMethod(GetType(T), prop.PropertyType)
 
            Dim orderByExpression = Expression.Lambda(Of Func(Of List(Of T), IEnumerable(Of T)))(Expression.[Call](orderByMethod, New Expression() {sourceParameter, propertySelectorLambda}), sourceParameter)
 
            cachedOrderByExpressions.Add(cacheKey, orderByExpression.Compile())
        End Sub
 
        Protected Overrides Sub RemoveSortCore()
            ResetItems(originalList)
        End Sub
 
        Private Sub ResetItems(ByVal items As List(Of T))
            MyBase.ClearItems()
 
            For i As Integer = 0 To items.Count - 1
                MyBase.InsertItem(i, items(i))
            Next
        End Sub
 
        Protected Overrides Sub OnListChanged(ByVal e As ListChangedEventArgs)
            originalList = MyBase.Items.ToList()
        End Sub
 
    End Class
 
End Namespace

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