VS 2008 CellValidating - Cannot Convert A DBNULL Value To STRING
Nov 2, 2009I am having a problem with the DIM statement. It is saying that it can not convert a DBNULL value to STRING even though there is something in the cell.
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Convert DBNull To Blank String In Access DB?
May 15, 2010I'm a new member to this site, and I have been searching for a solution to this problem.. Although I have found variations in the problem, nothing has seemed to work for me. Just started programming last year.
I am trying to populate text boxes in a form based on information from an Access Database. Everything is working, except when there are empty field values; the program then crashes because a DBNull value is returned. I set up an if statement to check the index as the rows are read for DBNull values, the problem is How do I actually change the value in the field from DBNull to a blank string ("") ?? Everything I try gives me an error, most often saying something about setting up an object. The problem happens within my if statement of the do loop...I'm thinking maybe I need to set up parameters ? Or an actual edit session within a datarow variable?[code]...
Use LINQ Query To Convert DBNull To String?
Oct 12, 2009I've created a small WPF app in VB9 to catalog our sizable DVD collection. This exercise has been more about learn programming than the need to have a movie database app, but I digress.The SQL database I created has a field for "Genre" that does not have an entry for all the movies in our collection. As such, when I run the method that filters the movie listing by "Genre" the compiler throws the "StrongTypingException was unhandled" error stating "The value for column 'Genre' in table 'Movies' is DBNull.".
I now understand where the DBNull problem comes from and have been searching for several hours to find a VB solution that converts the DBNull fields to strings on the fly during the LINQ query. I've found many solutions people have tried but, since I'm quite new to all this, none of them have worked for me. Pasted below is the method that throws the exception.
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VS 2008 DBNull To Type String Is Not Valid. From A Datagrid
Aug 13, 2010I am trying to populate a textbox.text with a value with a record from a datagrid. I can get my value from the datagrid by the following
Dim eRow As Integer
eRow = datagrid.CurrentRow.Index
txtSelecteditem.Text = datagrid.Item(0, eRow).Value
This all works fin when there is a value in the cell it is picking up. However, I hit a problem when this filed is blank.
The error I get is: Conversion from type 'DBNull' to type 'String' is not valid.
How can I get the textbox to populate with null if the field is null.
Convert DBNull To Date
Jun 5, 2011I wants to ask how to convert DBNull to Date type?
For Each row As DataRow In dt.Rows
i = 0
Dim array As Object = row.ItemArray
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array(i + 10) is datetime type, in the program above, if the Datetime column contains items, it still can run. However, when it loops to a row where the Datetime column does not have value of datetime (or the column is null), then an error " Conversion from type 'DBNull' to type 'Date' is not valid" is occured. I tried to use the if statements as program above but it seems like cannot works.
VS 2008 : Error: Conversion From Type 'DBNull' To Type 'String' Is Not Valid
Jun 15, 2009how can I solve this error without having to fill all of my fields. Some of the fields in my database are Nulls and some have records.
Error: Conversion from type 'DBNull' to type 'String' is not valid.
VS 2008 : Conversion From Type 'DBNull' To Type 'String' Is Not Valid
Jan 20, 2010I use following codes to retrieve data from table, but get error Conversion from type 'DBNull' to type 'String' is not valid.
str = "Select * from gpass where vou_no= " & Val(Me.txtGat.Text) & " And Date = '" & Me.txtDat.Text & "'"
dt = GetTable(str)
If (dt.Rows.Count > 0) Then
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VS 2008 Conversion From Type 'DBNull' To Type 'String' Is Not Valid?
Apr 29, 2009I am importing an Excel spreadsheet, turning it into a dataset and inserting the results into SQL Server (only 100 rows).
I am having an issue with one of the date columns in Excel, which can have a value or not. The "F" column is the one that may be blank and this is the error I get: Conversion from type 'DBNull' to type 'String' is not valid.
How can I add a check to the Dim F As Date = CDate(row(5)) to handle a null?
VB
' The use of letters instead of
' more descriptive variables is
' strictly for this sample peice
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Conversion Of DBNULL To String?
Apr 17, 2009Is it possible to converty a type System.DBNULL to a string type?
View 3 RepliesDBNull To Type String Is Not Valid
Mar 5, 2012I have this problem that when the textbox don't have a value I always get this error "Conversion from type 'DBNull' to type 'String' is not valid." [code]...
View 1 RepliesDBNull To Type String Is Not Valid?
Feb 5, 2011I am receiving the following error "Conversion from type 'DBNull' to type 'String' is not valid" when checking a textedit control to see if it is empty or more than 1 characters in length.
Public Class CustomValidationRule
Inherits ValidationRule
Public Overrides Function Validate(ByVal
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[2008] KeyPress - Convert To A String And Add It To Overall String?
Aug 3, 2011Currently, I'm using the following code to pull info from the management class.
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I'm also pulling info from the bios, disk drives, video, etc. What I've noticed, is although it runs fine on my pc, it may error out on some pcs since it is hardware dependent.I'm having trouble implementing a check to find if it exists before I convert to a string and add it to my overall string.
.net - Why RowLeave Fires Before CellLeave/CellValidating
Mar 19, 2009I have an update statement under RowLeave event of my datagridview. Before I update it I need to validate the cell if there is an empty value. But whenever I moved the focus to another row, RowLeave is called first before CellLeave/CellValidating.Is there another way of validating the cell when leaving a row?
Note: Leaving a cell in the same row is not a problem.
Sql - Validate Datagridview Using The Cellvalidating Event
Jun 5, 2009I have a datagridview that I would like to validate using the cellvalidating event. however as the user doesnt navigate between cells or rows in the datagridview. just enters data in a cell in the datagridview and then clicks a save button the cellvalidating event doesnt get fired.
View 4 Replies.net - LINQ Replace DBNull With Blank String?
Mar 10, 2010In this example, an error is raised if either row.FirstName or row.LastName are NULL.
How do I rewrite the Select clause, to convert a DBNull value to a blank string ""?
Dim query = From row As myDataSet.myDataRow in myDataSet.Tables("MyData") _
Select row.FirstName, row.LastName
NOTE: Since the DataSet is strongly-typed. I can use row.isFirstNameNull(), but IIF(row.isFirstNameNull(), "", row.FirstName) will not work since all parameters are referenced.
Conversion From Type DBNull To String Is Not Valid
Jun 21, 2010I have the following code:
tb_Job_No.Text is a combobox
This is the code:
Public Sub RepCD_process()
ssql_Job = "SELECT * FROM Rep_Dist"
ssql_Job = ssql_Job + " WHERE (Job_Number = '" & tb_Job_No.Text & "') "
Dim Main_Form As New Main_Form
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Can't seem to get pasted this, when it is remark out all works. How to correct this and get data into the listview?
Conversion From Type DBNull To String Not Valid
Feb 16, 2008Populating a datatable from Access gives me this exception where a record has an empty field. How do I handle it?
System.InvalidCastException was unhandled
Message="Conversion from type 'DBNull' to type 'String' is not valid."
Code:
Private Sub ShowData()
lblCustNo.Text = CStr(dtOrderEntry.Rows(intCurrRow)("CustNo"))
lblCustName.Text = CStr(dtOrderEntry.Rows(intCurrRow)("CustName"))
lblAddr1.Text = CStr(dtOrderEntry.Rows(intCurrRow)("Addr1"))
lblAddr2.Text = CStr(dtOrderEntry.Rows(intCurrRow)("Addr2"))
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Operator = Is Not Defined For Type String And Dbnull
Oct 9, 2010Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim connectionString As String
Dim cnn As OleDbConnection
Dim adptr As OleDbDataAdapter
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Change The Value Of A Cell In DataGridView.CellValidating Event?
Sep 8, 2011I handle the validation in the CellValidating event, and if the cell is invalid display an error message, then cancel the exit of edit mode. However I would also like to erase the content of the cell currently in edit mode.
View 18 RepliesVS 2008 Convert .jpg To String?
Jun 10, 2009I need to take a picture, test.jpg and read it in and convert it to a string.
The string is going to be sent via email attactment where i need it to work as a .jpg when i download the file attachment.
I can only build the file attachment using a String so i will need to convert the picture into a string, without losing any of the data bytes.
.net - Convert String To A Date 21/08/2008 00:21:00?
Sep 28, 2010I'm using vb.net 2005. How do convert this date / time 21/08/2008 00:21:00 to a DateTime object ?
View 4 RepliesConvert A Listbox To A String In Vb 2008?
Oct 31, 2009how would i convert a listbox to a string in vb 2008
View 5 RepliesConvert An ASCII String To Hex For VB 2008?
Jun 13, 2010I'm trying to convert an ASCII String to hex for VB 2008. So far I have this :
Code:
Function asc2hex(ByVal StrName As String) As String
Dim loopCount As Integer, strHold As String
For loopCount = 1 To Len(StrName)
strHold = strHold & Hex(Asc(Mid(StrName, loopCount, 1)))
Next loopCount
asc2hex = MsgBox(strHold)
End Function
However, It is not reporting all the bytes that it should be. For example: This is the correct format.
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VS 2008 - How To Convert Unicode To String
Oct 17, 2010How would I convert a Text File that is Unicode into string (readable text)?
View 1 RepliesVS 2008 : Convert A Resource To String?
Apr 28, 2010How do I convert a Resource to String? I dont want the Resource to be "written" or "extracted" from the program.
View 1 RepliesVS 2008 : Convert String To Barcode?
Jun 22, 2009I am looking for a good example code to convert a string to barcode.
View 9 RepliesVS 2008 Convert 2d Array Into A String?
Nov 20, 2009converting a 2 array into a string At the moment I have a 2 array and a string
The 2d array goes as follows:
0 1 2 3 4 5
0 1 2 3 4 5
0 1 2 3 4 5
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I have tried to use the string to char method but its not working
VS 2008 Convert Float Value To String?
Jul 26, 2010how would i go about converting a float value to string?
View 9 RepliesVS 2008 Convert String To Date
May 18, 2010example: I have these 2strings: Quote:
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VS 2008 Convert String To HTMLDocument?
Feb 21, 2010I have a string in html format and i want to convert it to an htmldocument.
View 12 Replies
