johann36
Messages postés130Date d'inscriptiondimanche 15 février 2004StatutMembreDernière intervention 9 mai 2017
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29 août 2008 à 08:31
johann36
Messages postés130Date d'inscriptiondimanche 15 février 2004StatutMembreDernière intervention 9 mai 2017
-
29 août 2008 à 13:50
Bonjour à tous,
J'essaie tant bien que mal de me sortir de ce pétrin mais rien à y faire c'est la galère. Je lutte depuis maintenant 3 semaines sur un problème d'affichage de données d'environ 15000 enregistrements pour une DataGrid.
Après mainte et mainte recherche et message on m'a orienté vers le mode virtuel (ce qui me semble le plus approprié) et aujourd'hui me revoilà pour énième problème qui est le suivant :
Pour info j'ai récupéré le code source sur le msdn de microsoft (implémenter le mode virtuel dans le contrôle DataGridView Windows Forms)
Public ReadOnly Property Columns() As DataColumnCollection
Get
' Return the existing value if it has already been determined.
If columnsValue IsNot Nothing Then
Return columnsValue
End If
' Retrieve the column information from the database.
command.CommandText = "SELECT * FROM " & tableName
'Dim adapter As New SqlDataAdapter()
Dim adapter As New OdbcDataAdapter
adapter.SelectCommand = command
Dim table As New DataTable()
table.Locale = System.Globalization.CultureInfo.InvariantCulture
adapter.FillSchema(table, SchemaType.Source)
columnsValue = table.Columns
Return columnsValue
End Get
End Property
Cette fonction (me semble t-il) récupère les noms de champs contenu dans la table, j'utilise une bdd interbase (*.gdb) le code que j'ai récupéré est pour sql server donc j'essaie de l'adapter mais avec mon p'tit cerveau c'est pas gagné. Le problème vient de la ligne que j'ai mis en rouge "adapter.FillSchema(table, SchemaType.Source)" j'ai un message d'erreur qui est le suivant "FillSchema : la propriété SelectCommand.Connection n'a pas été initialisée.".
Merci d'avance à tous.
PS : Je débute en .Net et à part m'arracher les cheveux c'est tout ce que j'arrive à faire. Elle est ou l'astuce pour devenir un vrai développeur ? Il faut avoir un BAC +10 ou s'appeler heinstein ?
cs_casy
Messages postés7741Date d'inscriptionmercredi 1 septembre 2004StatutMembreDernière intervention24 septembre 201440 29 août 2008 à 13:20
Ta propriété SelectCommand fait référence à un objet command qui lui m^me devrait normalement faire référence à un objet connexion (on ne le voit pasdans le code)
Cet objet connexion doit avoir comme chaine de connection (propriété connectionString) une chaine de connection correcte pour interroger ta base.
De plus pour avoir accès à la base, il faut que la connection soit ouverte.
johann36
Messages postés130Date d'inscriptiondimanche 15 février 2004StatutMembreDernière intervention 9 mai 2017 29 août 2008 à 13:50
En faite je n'ai mis que le code qui me pose problème pour bien faire il faudrait que je mette le code complet, j'espère que sa va pas être trop long mais bon sa va certainement être plus claire :
Public Class VirtualJustInTimeDemo
Inherits System.Windows.Forms.Form
Private WithEvents dataGridView1 As New DataGridView()
Private memoryCache As Cache
' Specify a connection string. Replace the given value with a
' valid connection string for a Northwind SQL Server sample
' database accessible to your system.
Private connectionString As String = _
"Driver=Firebird/InterBase(r) driver;Server=localhost;" + _
"Database=localhost:C:\Fluox.gdb;Uid=SYSDBA;Pwd=masterkey;"
Private table As String = "COULEE"
Private Sub VirtualJustInTimeDemo_Load( _
ByVal sender As Object, ByVal e As EventArgs) _
Handles Me.Load
' Initialize the form.
With Me
.AutoSize = True
.Controls.Add(Me.dataGridView1)
.Text = "DataGridView virtual-mode just-in-time demo"
End With
' Complete the initialization of the DataGridView.
With Me.dataGridView1
.Size = New Size(800, 250)
.Dock = DockStyle.Fill
.VirtualMode = True
.ReadOnly = True
.AllowUserToAddRows = False
.AllowUserToOrderColumns = False
.SelectionMode = DataGridViewSelectionMode.FullRowSelect
End With
' Create a DataRetriever and use it to create a Cache object
' and to initialize the DataGridView columns and rows.
Try
Dim retriever As New DataRetriever(connectionString, table)
memoryCache = New Cache(retriever, 16)
For Each column As DataColumn In retriever.Columns
dataGridView1.Columns.Add( _
column.ColumnName, column.ColumnName)
Next
Me.dataGridView1.RowCount = retriever.RowCount
Catch ex As SqlException
MessageBox.Show("Connection could not be established. " & _
"Verify that the connection string is valid.")
Application.Exit()
End Try
' Adjust the column widths based on the displayed values.
Me.dataGridView1.AutoResizeColumns( _
DataGridViewAutoSizeColumnsMode.DisplayedCells)
End Sub
Private Sub dataGridView1_CellValueNeeded( _
ByVal sender As Object, ByVal e As DataGridViewCellValueEventArgs) _
Handles dataGridView1.CellValueNeeded
<STAThreadAttribute()> _
Public Shared Sub Main()
Application.Run(New VirtualJustInTimeDemo())
End Sub
End Class
Public Interface IDataPageRetriever
Function SupplyPageOfData( _
ByVal lowerPageBoundary As Integer, ByVal rowsPerPage As Integer) _
As DataTable
End Interface
Public Class DataRetriever
Implements IDataPageRetriever
Private tableName As String
'Private command As SqlCommand
Private command As New OdbcCommand
Public Sub New(ByVal connectionString As String, ByVal tableName As String)
'Dim connection As New SqlConnection(connectionString)
Dim connection As New Odbc.OdbcConnection(connectionString)
connection.Open()
'command = connection.CreateCommand()
Me.tableName = tableName
End Sub
Private rowCountValue As Integer = -1
Public ReadOnly Property RowCount() As Integer
Get
' Return the existing value if it has already been determined.
If Not rowCountValue = -1 Then
Return rowCountValue
End If
' Retrieve the row count from the database.
command.CommandText = "SELECT COUNT(*) FROM " & tableName
rowCountValue = CInt(command.ExecuteScalar())
Return rowCountValue
End Get
End Property
Private columnsValue As DataColumnCollection
Public ReadOnly Property Columns() As DataColumnCollection
Get
' Return the existing value if it has already been determined.
If columnsValue IsNot Nothing Then
Return columnsValue
End If
' Retrieve the column information from the database.
command.CommandText = "SELECT * FROM " & tableName
'Dim adapter As New SqlDataAdapter()
Dim adapter As New OdbcDataAdapter
adapter.SelectCommand = command
Dim table As New DataTable()
table.Locale = System.Globalization.CultureInfo.InvariantCulture
adapter.FillSchema(table, SchemaType.Source)
columnsValue = table.Columns
Return columnsValue
End Get
End Property
Private commaSeparatedListOfColumnNamesValue As String = Nothing
Private ReadOnly Property CommaSeparatedListOfColumnNames() As String
Get
' Return the existing value if it has already been determined.
If commaSeparatedListOfColumnNamesValue IsNot Nothing Then
Return commaSeparatedListOfColumnNamesValue
End If
' Store a list of column names for use in the
' SupplyPageOfData method.
Dim commaSeparatedColumnNames As New System.Text.StringBuilder()
Dim firstColumn As Boolean = True
For Each column As DataColumn In Columns
If Not firstColumn Then
commaSeparatedColumnNames.Append(", ")
End If
commaSeparatedColumnNames.Append(column.ColumnName)
firstColumn = False
Next
commaSeparatedListOfColumnNamesValue = _
commaSeparatedColumnNames.ToString()
Return commaSeparatedListOfColumnNamesValue
End Get
End Property
' Declare variables to be reused by the SupplyPageOfData method.
Private columnToSortBy As String
Private adapter As New Odbc.OdbcDataAdapter()
Public Function SupplyPageOfData( _
ByVal lowerPageBoundary As Integer, ByVal rowsPerPage As Integer) _
As DataTable Implements IDataPageRetriever.SupplyPageOfData
' Store the name of the ID column. This column must contain unique
' values so the SQL below will work properly.
If columnToSortBy Is Nothing Then
columnToSortBy = Me.Columns(0).ColumnName
End If
If Not Me.Columns(columnToSortBy).Unique Then
Throw New InvalidOperationException(String.Format( _
"Column {0} must contain unique values.", columnToSortBy))
End If
' Retrieve the specified number of rows from the database, starting
' with the row specified by the lowerPageBoundary parameter.
command.CommandText = _
"Select Top " & rowsPerPage & " " & _
CommaSeparatedListOfColumnNames & " From " & tableName & _
" WHERE " & columnToSortBy & " NOT IN (SELECT TOP " & _
lowerPageBoundary & " " & columnToSortBy & " From " & _
tableName & " Order By " & columnToSortBy & _
") Order By " & columnToSortBy
'adapter.SelectCommand = command
Dim table As New DataTable()
table.Locale = System.Globalization.CultureInfo.InvariantCulture
adapter.Fill(table)
Return table
End Function
End Class
Public Class Cache
Private Shared RowsPerPage As Integer
' Represents one page of data.
Public Structure DataPage
Public table As DataTable
Private lowestIndexValue As Integer
Private highestIndexValue As Integer
Public Sub New(ByVal table As DataTable, ByVal rowIndex As Integer)
' Sets the value of the element parameter if the value is in the cache.
Private Function IfPageCached_ThenSetElement(ByVal rowIndex As Integer, _
ByVal columnIndex As Integer, ByRef element As String) As Boolean
If IsRowCachedInPage(0, rowIndex) Then
element = cachePages(0).table.Rows(rowIndex Mod RowsPerPage) _
.Item(columnIndex).ToString()
Return True
ElseIf IsRowCachedInPage(1, rowIndex) Then
element = cachePages(1).table.Rows(rowIndex Mod RowsPerPage) _
.Item(columnIndex).ToString()
Return True
End If
Return False
End Function
Public Function RetrieveElement(ByVal rowIndex As Integer, _
ByVal columnIndex As Integer) As String
Dim element As String = Nothing
If IfPageCached_ThenSetElement(rowIndex, columnIndex, element) Then
Return element
Else
Return RetrieveData_CacheIt_ThenReturnElement( _
rowIndex, columnIndex)
End If
End Function
Private Sub LoadFirstTwoPages()
cachePages = New DataPage() { _
New DataPage(dataSupply.SupplyPageOfData( _
DataPage.MapToLowerBoundary(0), RowsPerPage), 0), _
New DataPage(dataSupply.SupplyPageOfData( _
DataPage.MapToLowerBoundary(RowsPerPage), _
RowsPerPage), RowsPerPage) _
}
End Sub
Private Function RetrieveData_CacheIt_ThenReturnElement( _
ByVal rowIndex As Integer, ByVal columnIndex As Integer) As String
' Retrieve a page worth of data containing the requested value.
Dim table As DataTable = dataSupply.SupplyPageOfData( _
DataPage.MapToLowerBoundary(rowIndex), RowsPerPage)
' Replace the cached page furthest from the requested cell
' with a new page containing the newly retrieved data.
cachePages(GetIndexToUnusedPage(rowIndex)) = _
New DataPage(table, rowIndex)
Return RetrieveElement(rowIndex, columnIndex)
End Function
' Returns the index of the cached page most distant from the given index
' and therefore least likely to be reused.
Private Function GetIndexToUnusedPage(ByVal rowIndex As Integer) _
As Integer
If rowIndex > cachePages(0).HighestIndex AndAlso _
rowIndex > cachePages(1).HighestIndex Then
Dim offsetFromPage0 As Integer = _
rowIndex - cachePages(0).HighestIndex
Dim offsetFromPage1 As Integer = _
rowIndex - cachePages(1).HighestIndex
If offsetFromPage0 < offsetFromPage1 Then
Return 1
End If
Return 0
Else
Dim offsetFromPage0 As Integer = _
cachePages(0).LowestIndex - rowIndex
Dim offsetFromPage1 As Integer = _
cachePages(1).LowestIndex - rowIndex
If offsetFromPage0 < offsetFromPage1 Then
Return 1
End If
Return 0
End If
End Function
' Returns a value indicating whether the given row index is contained
' in the given DataPage.
Private Function IsRowCachedInPage( _
ByVal pageNumber As Integer, ByVal rowIndex As Integer) As Boolean