When i try this
oAssembly = Assembly.LoadFrom("C:\dynamicdlls\Microsoft.Office.Interop.Word.dll")
oType = oAssembly.GetType("Microsoft.Office.Interop.Word.Application")
Try
oObject = Activator.CreateInstance(oType)
Dim doc As Object = oObject.Documents.Open("C:\worddoc\test.docx")
Dim count As Integer = doc.Words.Count
For i As Integer = 1 To count
Dim text As String = doc.Words(i).Text
Console.WriteLine("Word {0} = {1}", i, text)
Next
oObject.Quit()
Catch ex As Exception
MsgBox(ex.ToString)
End Try
I get "Cannot create an instance of an interface".
I Know there is a better alternative to this, I am just exploring this method and would like to know if this is possible and how would one do it.
Related
Trying to fix a warning and not sure how to restructure code as reader.IsClosed is throwing a warning that states "Variable 'reader' is used before it has been assigned a value. A null reference exception could result at run time." Logistically, since reader As SqlDataReader && reader is not initialized with a value then I could ignore as should be fine at runtime, but my inexperience would make me believe there is a better way?
Public Function GetTotalItems(ByVal userId As Long) As Int16
Dim lstParam As List(Of SqlParameter) = New List(Of SqlParameter)()
Dim tablMd = Me.GetMetaData()
Dim retList As ArrayList = New ArrayList()
lstParam.Add(New SqlClient.SqlParameter("#" + tablMd.PrimaryKey.ColumnName, 0))
lstParam.Add(New SqlClient.SqlParameter("#UserID", userId))
lstParam.Add(New SqlClient.SqlParameter("#ActionFlag", "SELECT_ITEMS_COUNT"))
Dim spName As String = Me.GetStoreProcname()
Dim reader As SqlDataReader
Try
reader = SqlHelper.ExecuteReader(
Utility.GetConnectionStringSetting(),
CommandType.StoredProcedure,
Me.GetStoreProcname(),
lstParam.ToArray()
)
If (reader.HasRows = True) Then
If (reader.Read()) Then
Dim value As Object = reader(0)
Return CInt(value)
End If
End If
Catch ex As Exception
Throw
Finally
If Not reader.IsClosed Then
reader.Close()
End If
End Try
Return 0
End Function
We can narrow the problem down to this excerpt:
Dim reader As SqlDataReader
Try
reader = SqlHelper.ExecuteReader( ... )
Finally
If Not reader.IsClosed Then reader.Close()
End Try
The problem comes if an exception is thrown by the ExecuteReader() function. In that event, the reader variable is never assigned a value. It's still Nothing when you try to evaluate reader.IsClosed, and that will cause an exception.
Given you don't actually do anything with the exception and the SqlHelper takes care of the connection and command objects, you can narrow the entire function down to just this:
Public Function GetTotalItems(ByVal userId As Long) As Int16
Dim lstParam = {
New SqlClient.SqlParameter("#" + Me.GetMetaData().PrimaryKey.ColumnName, 0),
New SqlClient.SqlParameter("#UserID", userId),
New SqlClient.SqlParameter("#ActionFlag", "SELECT_ITEMS_COUNT")
}
Using reader As SqlDataReader = SqlHelper.ExecuteReader(
Utility.GetConnectionStringSetting(),
CommandType.StoredProcedure,
Me.GetStoreProcname(),
lstParam)
If reader.Read() Then Return CInt(reader(0))
End Using
Return 0
End Function
#jmcilhinney, #o_O, #Chris Dunaway ... Thank you for the help + appreciation + admiration for your knowledge + reverence == deverence(); ... This removed the error:
Public Function GetTotalAmount(ByVal userId As Long) As Decimal
Dim lstParam As List(Of SqlParameter) = New List(Of SqlParameter)()
Dim tablMd = Me.GetMetaData()
Dim retList As ArrayList = New ArrayList()
lstParam.Add(New SqlClient.SqlParameter("#" + tablMd.PrimaryKey.ColumnName, 0))
lstParam.Add(New SqlClient.SqlParameter("#UserID", userId))
lstParam.Add(New SqlClient.SqlParameter("#ActionFlag", "SELECT_TOTAL_AMOUNT"))
Dim spName As String = Me.GetStoreProcname()
Using reader As SqlDataReader = SqlHelper.ExecuteReader(
Utility.GetConnectionStringSetting(),
CommandType.StoredProcedure,
Me.GetStoreProcname(),
lstParam.ToArray()
)
If (reader.HasRows = True) Then
If (reader.Read()) Then
Dim value As Object = reader(0)
Return CDec(value)
End If
End If
End Using
Return 0
End Function
I have a form that retrieves the CurrentYearyear_now and NextYearyear_next from the database. It gives me the error 'IndexOutOfRangeException was unhandled' bcoz I think there is no row to be retrieved. And I wanted to do is, even though there's no data from the table, I can still load the forms and give me a null value to be displayed. I tried everything I know to make it work but I cant resolve the problem. Is there anyway to recode this.
Sub LoadSchoolYear()
Dim conn1 As New MySqlConnection("server=localhost; userid=root; password=root; database=uecp_cens")
Dim dAdapter1 As New MySqlDataAdapter("SELECT year_now, year_next FROM uecp_cens.tblschoolyear", conn1)
Dim dTable1 As New DataSet
Try
dAdapter1.Fill(dTable1, "uecp_cens")
lblYearNow.Text = dTable1.Tables("uecp_cens").Rows(0).Item(0).ToString
lblYearNext.Text = dTable1.Tables("uecp_cens").Rows(0).Item(1).ToString
Catch ex As MySqlException
MsgBox(ex.Message)
Finally
conn1.Dispose()
End Try
End Sub
Any help is appreciated.
If there is no row in the table as you've mentioned you get that error. So check Rows.Count:
Dim yearNow As String = Nothing
Dim yearNext As String = Nothing
If dTable1.Tables("uecp_cens").Rows.Count > 0 Then
yearNow = dTable1.Tables("uecp_cens").Rows(0).Item(0).ToString()
yearNext = dTable1.Tables("uecp_cens").Rows(0).Item(1).ToString()
End If
lblYearNow.Text = yearNow
lblYearNext.Text = yearNext
If instead the field is NULL in the DB it is DBNull.Value and you get an exception if you use Rows(0).Item(0).ToString(). Then use DataRow.IsNull to check it:
If dTable1.Tables("uecp_cens").Rows.Count > 0 Then
Dim row = dTable1.Tables("uecp_cens").Rows(0)
yearNow = If(row.IsNull(0), Nothing, row.Item(0).ToString())
yearNext = If(row.IsNull(1), Nothing, row.Item(1).ToString())
End If
this is my very first project on vb.net and i am now struggling to migrate a vba working add in to a vb.net COM Add-in. I think i'm sort of getting the hang, but error handling has me stymied.
This is a test i've been using to understand the try-catch and how to pass exception to caller
Public Sub test()
Dim ActWkSh As Excel.Worksheet
Dim ActRng As Excel.Range
Dim ActCll As Excel.Range
Dim sVar01 As String
Dim iVar01 As Integer
Dim sVar02 As String
Dim iVar02 As Integer
Dim objVar01 As Object
ActWkSh = Me.Application.ActiveSheet
ActRng = Me.Application.Selection
ActCll = Me.Application.ActiveCell
iVar01 = iVar02 = 1
sVar01 = CStr(ActCll.Value)
sVar02 = CStr(ActCll.Offset(1, 0).Value)
Try
objVar01 = GetValuesV(sVar01, sVar02)
'DO SOMETHING HERE
Catch ex As Exception
MsgBox("ERROR: " + ex.Message)
'LOG ERROR SOMEWHERE
Finally
MsgBox("DONE!")
End Try
End Sub
Private Function GetValuesV(ByVal QryStr As Object, ByVal qryConn As String) As Object
Dim cnn As Object
Dim rs As Object
Try
cnn = CreateObject("ADODB.Connection")
cnn.Open(qryConn)
rs = CreateObject("ADODB.recordset")
rs = cnn.Execute(QryStr)
If rs.EOF = False Then
GetValuesV = rs.GetRows
Else
Throw New System.Exception("Query Return Empty Set")
End If
Catch ex As Exception
Throw ex
Finally
rs.Close()
cnn.Close()
End Try
End Function
i'd like to have the error message up to test, but
MsgBox("ERRORE: " + ex.Message)
pops out something unexpected (Object variable or With block variable not set)
What am i doing wrong here??
Thanks
D
It may be because you're doing a
Throw ex
Try using
Throw
instead. This maintains the error stack, instead of generating a new one each time.
Based on your comments, I think the specific problem you're getting is in your Finally block. You're trying to close the recordset and the connection, but if you got an error when you instantiated them, they will not exist; therefore, you get the Object variable or with block error.
(I would put the connection is a using statement anyway).
This is my code. I keep having an error "value of type string cannot be converted to system.data.datatable"
Function GetTable() As DataTable
Dim SQLConnection As New SqlConnection(ConfigurationManager.ConnectionStrings("Zeinchatconnection").ToString())
Dim CommSQL As New SqlClient.SqlCommand
Dim ChatDataAdapter As SqlDataAdapter
Dim paramSQL As SqlClient.SqlParameter
Dim DStable As DataSet
Dim table As New DataTable
Dim szName As String = ""
Dim szNumber As String = ""
Try
If SQLConnection.State = ConnectionState.Closed Then
SQLConnection.Open()
End If
CommSQL.Connection = SQLConnection
CommSQL.CommandType = CommandType.StoredProcedure
CommSQL.CommandText = "spc_newselect"
CommSQL.ExecuteNonQuery()
ChatDataAdapter = New SqlDataAdapter(CommSQL)
ChatDataAdapter.Fill(DSTable)
table.Rows.Clear()
table.Clear()
table = DStable.Tables(0)
Dim i As Integer = 0
For i = 0 To table.Rows.Count - 1
szName = szName & " " & table.Rows(i).Item(0) & table.Rows(i).Item(1)
szNumber = szNumber & " " & table.Rows(i).Item(0) & table.Rows(i).Item(1)
Next
GetTable = "1"
Catch ex As System.Data.SqlClient.SqlException
GetTable = "0"
Catch ex As Exception
GetTable = "0"
If (IsNothing(ChatDataAdapter) = False) Then ChatDataAdapter.Dispose()
If (IsNothing(CommSQL) = False) Then CommSQL.Dispose()
SQLConnection.Close()
End Try
Return table
End Function
The part where the errors are is gettable= "1" and below.
GetTable = "1" indicates that you want to set the returnValue of your function. As your function is defined as Function GetTable() As DataTable your compiler shows an error!
A few lines below there is a correct return stmt (Return table) so I am not quite sure what your goal is with GetTable = "1"?
I would assume that you would like to have an additional returnValue indicating whether your function call was successful or not. But as a matter of fact functions may only have one returnValue.
You may choose to set your table var to nothing, or use a ref param ...
' possible solution 1 - using nothing value
Function GetTable() As DataTable
Try
' your code goes here
' remove GetTable = "1"
Catch ex as Exception
' change GetTable = "0" to
table = nothing
End Try
' other code ...
End Function
' possible solution 2 - ref param
Function GetTable(ByRef status as integer) as DataTable
Try
' your code goes here
' remove GetTable = "1"
status = 1
Catch ex as Exception
' change GetTable = "0" to
status = 0
End Try
' other code ...
End Function
At solution 2 you may also choose a boolean parameter indicating your call was successful or not.
Your function GetTable returns a DataTable
you can't convert "1" to a DataTable as the message suggests which is what is happening on the line GetTable = "1"
If you want to return a DataTable and Set a flag to see the status; change your function definition as so:
Function GetTable(byref result as Integer) As DataTable
Then instead of GetTable = "1" change this to result = 1. This way you can inspect the result value and return a DataTable:
Dim res as Integer
Dim dt as DataTable = GetTable(res)
If res = 1 then
'It worked!
End If
Side Note: Turn Option Strict On
I cannot seem to get or store the id of the post message I create. I am using this code to post a message:
Try
Dim fb = New FacebookClient(_accessToken)
AddHandler fb.PostCompleted, Function(o, e)
If (e.Cancelled) Then
ElseIf e.Error IsNot Nothing Then
MessageBox.Show(e.Error.Message)
Else
Dim result As Object = e.GetResultData()
_lastMessageId = result.Id
End If
Return MessageBox.Show("Message Posted successfully")
End Function
Dim parameters As Object = New ExpandoObject()
parameters.message = TextBox1.Text
fb.PostTaskAsync("me/feed", parameters)
MsgBox("This is the last message id " & _lastMessageId)
Catch ex As FacebookApiException
MessageBox.Show(ex.Message)
End Try
I just want to store the posted id so I can delete it later.
Here is the working code that i came up with thanks to prabir
Dim fb = New FacebookClient(_accessToken)
Dim parameters As Object = New ExpandoObject()
parameters.message = "Testing"
Dim task = fb.PostTaskAsync("me/feed", parameters)
task.ContinueWith(Function(t)
If t.Exception Is Nothing Then
Dim result As Object = t.Result
_lastMessageId = result.id
Else
MsgBox("error occurred")
End If
Return t.Result
End Function)
here is c# code which might help you get started with it.
Since you are using XTaskAsync methods use ContinueWith instead of PostCompleted.
fb.PostTaskAsync("me/feed", parameters)
.ContinueWith(t= > {
if(!t.IsFaulted) {
dynamic result = t.Result;
}
});
XTaskAsync methods returns Task<object>