VB.NET: Excel Crashes when Updating Data in a Word Chart - excel

Question

Update: Releasing objects has no effect on Excel crashing. The problematic line is:
Dim wChartData = wChart.ChartData
I have written a VB.Net application that opens a word document, iterates through the inline shapes, and updates each chart with data from the database. Sometimes Excel will crash when opening the sheet containing the chart data. Can anyone tell me how I fix this?
Here is the code that iterates through the shapes:
wApp = New Word.Application
wApp.Visible = True
wDoc = wApp.Documents.Add("Some_File_Name.docx")
Console.WriteLine("Updating Charts")
Dim chartName As String
For Each wShape As Word.InlineShape In wDoc.InlineShapes
If wShape.HasChart = Core.MsoTriState.msoTrue Then
If wShape.Chart.HasTitle Then
chartName = wShape.Chart.ChartTitle.Text
Else
chartName = "NO_TITLE"
End If
UpdateChart(wShape.Chart, reportID, reportTitle,
reportUser, curriculumYear, chartName)
End If
Next
The UpdateChart subroutine grabs a SQL query and some options related to the chart, then fires off the FillChartData subroutine below:
Public Sub FillChartData(ByRef wChart As Word.Chart, ByVal sql As String,
Optional ByVal addDataPointsToLabels As Boolean = False)
If sql = "" Then Exit Sub
Dim cmd = O.factory.CreateCommand()
cmd.CommandText = sql
cmd.Connection = O.con
O.factory.CreateDataAdapter()
Dim adapter = O.factory.CreateDataAdapter
adapter.SelectCommand = cmd
Dim dt As New System.Data.DataTable()
Dim ds As New System.Data.DataSet()
adapter.Fill(ds, "report_name")
dt = ds.Tables(0)
Dim wChartData = wChart.ChartData
Dim wChartWb As Excel.Workbook = wChartData.Workbook
Dim wChartSheet As Excel.Worksheet = wChartWb.Sheets(1)
Dim title As String = "No title"
If wChart.HasTitle Then title = wChart.ChartTitle.Text.ToString
Dim r As Excel.Range
r = wChartSheet.Range("A1")
r.CurrentRegion.Clear()
For i = 0 To dt.Columns.Count - 1
Dim c As System.Data.DataColumn = dt.Columns(i)
r.Offset(0, i).Value2 = c.ColumnName
Next
r = wChartSheet.Range("A2")
For Each row As System.Data.DataRow In dt.Rows
For i = 0 To row.ItemArray.Count - 1
r.Offset(0, i).Value2 = row.Item(i)
Next
r = r.Offset(1)
Next
r = wChartSheet.Range("A1")
If addDataPointsToLabels Then
While r.Value <> ""
r.Value &= " " & r.Offset(1).Value
r = r.Offset(0, 1)
End While
End If
wChartWb.Close()
releaseObject(r)
releaseObject(wChartSheet)
releaseObject(wChartWb)
releaseObject(wChartData)
r = Nothing
wChartSheet = Nothing
wChartWb = Nothing
wChartData = Nothing
GC.Collect()
End Sub
The releaseObject subroutine is as follows:
Private Sub releaseObject(ByVal obj As Object)
Try
System.Runtime.InteropServices.Marshal.ReleaseComObject(obj)
obj = Nothing
Catch ex As Exception
MessageBox.Show(ex.ToString)
obj = Nothing
End Try
End Sub
And here's the crash report:
Problem signature:
Problem Event Name: APPCRASH
Application Name: EXCEL.EXE
Application Version: 15.0.5007.1000
Application Timestamp: 5a5eb36d
Fault Module Name: EXCEL.EXE
Fault Module Version: 15.0.5007.1000
Fault Module Timestamp: 5a5eb36d
Exception Code: c0000005
Exception Offset: 002b71c8
OS Version: 6.1.7601.2.1.0.256.4
Locale ID: 1033
Additional information about the problem:
LCID: 1033
skulcid: 1033
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Thanks for your help!

Answer 1

You need to Activate the Word ChartData object to begin the inter-process communication between Word and Excel.
The example below is a simplified demonstration of code pattern and contains no error handling. This example also demonstrates releasing out of scope COM objects via the garbage collector. See this answer for more discussion on this COM clean-up procedure.
This code was verified against Office 2007.
Imports System.Runtime.InteropServices
Imports Excel = Microsoft.Office.Interop.Excel
Imports Word = Microsoft.Office.Interop.Word
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
InterOpWork("Embedded Excel Chart.docx")
COMCleanup()
End Sub
Sub InterOpWork(filePath As String)
Dim appWord As New Word.Application
Dim doc As Word.Document = appWord.Documents.Open((filePath))
Dim shp As Word.InlineShape = doc.InlineShapes(1)
Dim ch As Word.Chart = shp.Chart
Dim chData As Word.ChartData = ch.ChartData
chData.Activate() ' **** This is what your code is missing
Dim wb As Excel.Workbook = DirectCast(chData.Workbook, Excel.Workbook)
Dim appExcel As Excel.Application = DirectCast(wb.Application, Excel.Application)
Dim ws As Excel.Worksheet = DirectCast(wb.Worksheets("Sheet1"), Excel.Worksheet)
Dim rng As Excel.Range = ws.Range("B2:B4")
Dim dataToChange As Object(,) = DirectCast(rng.Value2, Object(,))
For i As Int32 = dataToChange.GetLowerBound(0) To dataToChange.GetUpperBound(0)
dataToChange(i, 1) = i * 2 + (5 - i)
Next
rng.Value = dataToChange
wb.Save()
wb.Close(False)
appExcel.Quit()
doc.Save()
doc.Close(False)
appWord.Quit()
End Sub
Private Sub COMCleanup()
Do
GC.Collect()
GC.WaitForPendingFinalizers()
Loop While Marshal.AreComObjectsAvailableForCleanup
End Sub
End Class