DataGridViewX.CurrentRow.Cells.Item(0).Value.ToString
If the item is blank and no data is entered it will throw a null exception, so the question is that how can I check if the item is null or not? Even using this:
If DataGridViewX.CurrentRow.Cells.Item(0).Value.ToString IsNot Nothing Then ...
Will throw the exception!
I want to display a message if the value of cell of my datagridview is Null.
View 1 RepliesWhat im trying to do is check a row for null values in my datagridview before saving the data back to my access database, in particular the first columns cell of the new row being added. This is the code I have so far'
Private Sub LatheprogramsBindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LatheprogramsBindingNavigatorSaveItem.Click
Dim test As String = Me.LatheprogramsDataGridView.Columns(1).ToString()
[code]....
How to check whether a column is null i use the following code but I got this error "Input string was not in a correct format."
[Code]....
I've been trying to feed a multi line textbox into a string array then check item by item if a string contains part of it.
[Code]...
Just started on vb.net
I have a combo box with "yes" and "no" with i select Yes i want the label2 to change the text to "yes" likewise with "no"
I've tried to code it in a logical way as possible but it just doesn't works except for the "wtf" so i think that overall my code is correct but the way i want to retrieve the selected item from combo box is wrong.
Public Class Form1
Dim aa As String
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
[Code].....
I'm building a custom calendar control that queries our database to display corporate events. Here is the situation, there is an EndDate value stored and on the dev system one of the events have a NULL value. No big deal since it's only a test system, but might as well check before trying to use it anyway on the safe side. I figured the following code would work:
While dr.Read()
corporateTable.Rows.Add(New Object() { _
Convert.ToDateTime(dr("EventBeginDate")) _
[code]....
The thing that really gets me is, at one point I had this:
, IIf(dr.IsDBNull(column), Convert.ToDateTime(dr("EventBeginDate")).AddDays(1), Convert.ToDateTime(dr("EventEndDate"))) _
Thinking that it should work because it should only evaluate the dr() if it's not NULL. However, it kept erroring out at the end because the value was in fact NULL.Why is it that even though I'm checking if it's NULL before using the value, it errors out at the part that doesn't get called unless it's not NULL? Does it have to do with the fact that I'm using the IIF() and it's evaluating the whole statement? Or, using the dr(), it evaluates at runtime?
I tried to execute a code that will display Book Titles in alphabetical order within a list box and received an ArgumentNullException (Value cannot be null. Parameter name: item) error.
Dim strBook As String
Array.Sort(_strBookTitle)
For Each strBook In _strBookTitle
Me.lstDisplay.Items.Add(strBook)
Next
am a beginner for vb.net, i was using the WROX book to start of with vb.net.In that i had an example code which i tried to work out but i got an error like this one ,am jus creating an array and adding it into the list value cannot be null.Parameter name:item
[Code]...
I have some code which gets child items for a menu via the GetChildren function which takes a list of menuData: Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
If menuData.Children IsNot Nothing Then
menuData.Children.AddRange(GetChildren(menuData))
End If
Next
If I check if menudata.children isnot nothing, it always is nothing because the GetChildren function is yet to run (providing the child items, which do exist). If I remove this check and just have this code:
Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
menuData.Children.AddRange(GetChildren(menuData))
Next
Then I am presented with a Object reference not set to an instance of an object error on menuData.Children.AddRange(GetChildren(menuData))
All I want to do is check if an object is null, but no matter what I do, if it compiles, it throws a NullReferenceException just trying to check! Here's what I've done:
[Code]...
I have a dataset. I'd like to check if one item in the dataset is null or zero.
If IsDBNull(ds.Tables(0).Rows(0)("TotalCostPerUnit")) or CInt(ds.Tables(0).Rows(0)("TotalCostPerUnit") = 0 Then
Exit Sub
end if
Dim Conn As ADODB.Connection
Dim Null As String
Dim NullRecordset As ADODB.Recordset
[code]....
Im trying to check my database for a null value. If the database is null, then I want it to start the timer, otherwise I want it to skip over some stuff and automatically load the main form.
I am trying to check to see if a DataSet is null or not. If it is I would like to show a MessageBox. For some reason it is not recognizing null returns and skipping the message box and going right to the Else commands. [code]....
View 3 RepliesI have a problem with verifying db null value. Actually I don't know the syntax.
Here is the code.
If Not IsDBNull(Me.DeliveryReviewDataSet.Delivery(Me.CustomerIDListBox.SelectedIndex).Signature) Then
"Signature" is the image field (binary data).
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If MyBase.Dispose(disposing) <> DBNull.Value Then
Dispose() = DBNull.Value
[Code]....
I am getting error
1) Expression does not produce a value.
2)Expression is a value and therefore cannot be the target of an assignment.
I retrieve data from database like below. How do I check whether the value retrieved from database is null?
[Code]...
i'm working with a database application and i want to check if there is a null value in a specific column but it works only when its not null but if its null it throws an exception automatically
i tried to change the nullvalue property of this column but i'm not able it shows a message that its not a valid property
i tried to change the source code in the code editer but it changes back automatically
I am working on a program that has many integers (q1, q2, etc.), and each of them can be 0 or 1. This is dependent on which radiobuttons are selected. I need it to check and make sure that all of the integers have a value, but since "Null" is the same as "0",
View 8 RepliesI have multiple textboxes that are saved using my settings and buttons to add them to the clipboard.
The problem is when the textbox is blank and I click on the copy button.
The saving to my.settings happens on close so when someone enters text that they plan on saving later and then clicks the copy button, whammo it crashes.
Here is the code that is failing and I need to check to make sure that there is a value before setting the text on the windows clipboard.[code]...
I just want to check and see if this object is null. if i do not and it is my applications closes.I have also looked into a null reference exception. I will do whatever as long as it handles "null".[code]
View 2 RepliesHow can I check if a datatable has never been set ? or Null or Nothing ? I don't mean empty Datatable ... For example,
[Code]...
[if me.textbox1.text= system.dbnull then msgbox("please inter a value")] it says system.dbnull can't be used as an expression so how can i check the if the textbox has a null value
View 13 RepliesTable contains 2 columns Tags10 and TU. Its values are:
NDX___________TUI48
JJI_________ NULL
CmdSelect.CommandText = "Select * From Tags Where Tags10='" & s_temp02 & "'" 'OK
ReaderSelect= CmdSelect.ExecuteReader() 'OK
[code]....
How to check this? If NULL there is nothing to do, if not NULL, we should put the value into s_temp03.
i hav two openfilefialogs(1 and 2). So i also have a listbox. the files opened with the openfiledialogs will be added to the listbox. and when i need to open the files i need to see if they are from which openfiledialog. so
it is like this.
Path.GetDirectoryName(OpenFileDialog1.FileName) & "" & Form3.ListBox1.SelectedItem.ToString
'if this returns a null then go to this
Path.GetDirectoryName(OpenFileDialog2.FileName) & "" & Form3.ListBox1.SelectedItem.ToString
Check multiple expressions for null?I have this bit here[code]...
View 8 Replies I am getting product id value some times null and empty from databasehere how i check if valule null and empty
productid = IIf(IsDBNull(TempDT.Rows(0).Item("productid")) =
True,
"", TempDT.Rows(0).Item("productid"))
[code].....
I have a sub that updates a form on certain occasions. Sometimes I need to update a form when some of the entries in my table will still have a NULL value. I used this code to prevent the sub from trying to fill the form fields with NULL data:
[Code]...
Basically, when you set an Integer to "Nothing" it seems to equal the same value as if you were to set it to 0. So, in a function that returns an Integer how can I return something that will show that the function failed? In most cases I would use -1 or something but in this case I need to allow for negative values too.
Here's some more detailed information: I'm using the GetValue method of the Microsoft.Win32.RegistryKey class to read a numeric value from the registry. The GetValue method has an optional argument that you can pass in that specifies what should be returned if the value did not exist, normally I would use Nothing but in this case because I am storing the returned value in an Integer then it is just the same as if the GetValue method returned 0 (which is a valid value in this case).
Example:
vb.net
Dim Reg As Microsoft.Win32.RegistryKey = My.Computer.Registry.LocalMachine
Dim SubKey As Microsoft.Win32.RegistryKey = Reg.OpenSubKey("SYSTEMCurrentControlSetControlTimeZoneInformation", False)
[Code].....
I have a property called ReplacementTo and I set a value to it based on the selecteditem from the combobox, like this:
classEquipmentItem.ReplacementTo = cmbReplcmnt.SelectedItem.ToString
Now I can't use cmbReplcmnt.Text because what I actually need is the value of that SelectedItem
So problem is, if the user leaves the combobox as blank, it throws a null exception.I decided to use the IIf function then:classEquipmentItem.ReplacementTo = IIf(IsNothing(cmbReplcmnt.SelectedItem.ToString), classEquipmentItem.ReplacementTo = "", cmbReplcmnt.SelectedItem.ToString)
Unfortunately I still get the error I tried using a Try-Catch for it and it worked, but I don't want to rely on the Try-Catch, so I was wondering is there a another way to work this through?