I am getting an unusual error "Nullable object must have a value" when running the code below.
[Code].....
Interestingly the Stored proc used by the table adapter still runs and does the insert but the function returns the error.
I have an insert query set up for my VB table adapter. It includes all the columns in my table. Some of these columns are Nullable VARCHAR and DATE and I want to set them to null on the insert.
In my code I have two varaibles defined as Dim Sdate as nullable (of date) Dim Sdata as nullable (of Char)
And I set them as follows:
Sdate = nothing
Sdata = nothing
On the insert query the "Catch" is activated and displays "Nullable Object must have a value"
I Sdate and Sdata have values, then the insert works just fine.
I have a bigger code block which I have recreated in this simpler example:
[Code]...
Okay, none of the previous questions I have seen with this error seem to apply in this situation.tEmp is a class that contains (among other things) two nullable date fields.[code]During a routine on my form, I am attempting to see if the following conditions are true[code]I get the above error (the title of question), but when I hover over the debugger, NextReview and InsuranceEligibleDate are both Nothing (which is correct for the employee I am looking at).I am using VB2010, and the Properties in the Employee class are using the new way of declaring Properties (i.e. no set/get)
View 4 RepliesI'm trying to assign a date object to nullable but my code error on CBDate1 = nullDate. The message indicates that I need to assign a value to a nullable. This is my first time using nullable[code\]...
View 9 RepliesI'm trying to assign a date object to nullable but my code error on CBDate1 = nullDate. The message indicates that I need to assign a value to a nullable. This is my first time using nullable.
[Code]....
In the code base I'm working in there have a method that has the signature
Public Sub SetDropDownValue(Of T As Structure)(ByVal target As ListControl, ByVal value As Nullable(Of T))
The method I am writing is passed a parameter of type object.
How can I cast the object into something that can be passed into the SetDropDownValue method?
I have a structure that contains another structure. The inner structure is nullable. Now wht I do is something like the following. I create a new instance of the inner structure, set the member variables and assign the whole structure to the inner structure of the parent. But it is giving an error. The assignment is not successful. If I try to peek into the structure in the watch window, it says "property evaluation failed" for the HasValue and Value properties.
Dim testData As List(Of TestData) = Nothing
Dim testData_List1 As New TestData
With testData_List1.commonTestParam
[Code].....
The code I want to work:
<Extension()>
Public Function NValue(Of T)(ByVal value As Nullable(Of T), ByVal DefaultValue As T) As T
Return If(value.HasValue, value.Value, DefaultValue)
[code].....
This function loops all properties of an object to create the updatequery to save te object to the DB.
We had to make some changes to it because of the introduction of nullable properties. If the property is nullable we would like to check the 'HasValue' property. This does works when it has a value. When the property has no value we get an 'Non-static method requires a target'-error at the CBool-line
An other way to check the 'HasValue'-prop of a property using reflection?
Private Function GetUpdateQuery(ByVal obj As Object, ByRef params As List(Of SqlParameter), Optional ByVal excl As String() = Nothing) As String
Dim sql As String = String.Empty
[Code].....
I have a generic Class I'm using to hold information loaded from a database.I have a method which takes a DataRow as an argument, uses the object's known column name and extracts the data from the DataRow, such that:Dim loadData As T = CType(myDataRow("myColumnName"), T))works as my default assignment in most cases.Unfortunately, due to some horrifying design constraints, some of my columns may be null, and may also be taken from enumerations.This means that when <T> is Nullable(Of SomeEnumeration) the above code does not work because I can't cast 0 directly to SomeEnumeration.Zero.Is there some way to check whether <T> is Nullable(Of [Enum])? Or some way to write a method which allows Integers to be cast to Nullable(Of [Enum])?I feel like I'm forgetting something that would allow me to write one of the other of these, but my weak google-fu is turning up nothing.
EDIT: Okay, thanks to dasblinkenlight's answer below, I can detect when this circumstance is occurring, but what I need to do now is to take a type <T> which I know is Nullable(Of SomeClass), get a type reference to SomeClass and then create a new object of type Nullable(Of SomeClass) and assign that to LoadData.My problem was that I had a lot of difficulty in finding any function which would accept baseType as an actual Type.Parse accepted baseType as a parameter, I knew baseType was an [Enum] type because of dasblinkenlight's code, so I was, in this instance, able to code a solution. It's a solution which is very specific to my problem (i.e., T is Nullable(of SomeEnumeration)), but it's a solution nonetheless.
I have Nullable properties in my class:Public Property FileStatusID() As Integer?
Get
Return m_FileStatusID
End Get
[code].....
[Code]...
When x is nullable I get an error 'Overload resolution failed because no accessible ToString accepts this number of arguments'. I suppose I could copy the nullable variable into a non-nullable variable, then format it, but that seems extremely clumsy for something that should be fairly simply. Isn't there a better way?
Arghh! Copying the Date? variable into a Date variable doesn't work-Option Strict is On & that sees the two variables as being of different types. Is it really necessary to to an explicit CDate conversion on a nullable date variable?
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I'm using my data objects in a crystal report. The thing is, when I select my object, it gets added to the field explorer table. My properties are listed except for the Nullable Type properties. Why would this happen. I've had quite a few issues yesterday as this is my first attempt at a crystal report in .Net. I thought I worked around them but now I've hit this snag.
View 11 RepliesQuote:Value of type System.Nullable(Of Decimal) cannot be converted to System I have the code below which seems to work fine on my development server but causes a compilation error when I put it on my live webserver (uncommented).The error message I get from the event viewer in IIS is as above.
' <WebMethod(Description:="Insert into Referral Payments Table.")> _
'Public Function InsertReferralPayment(ByVal ReffererCustID As Integer, ByVal InstalledCustID As Integer, ByVal AmountReferrer As Nullable(Of Decimal), ByVal AmountInstalled As Nullable(Of Decimal), ByVal ReferrerChequeSentDate As Nullable(Of Date), ByVal InstalledChequeSentDate As Nullable(Of Date), ByVal ReferrerChequeNo As Integer, ByVal InstalledChequeNo As Integer, ByVal InputBy As String) As Integer
[code]....
From what I can tell IIS is configured the same and both referenced DataTables seem identical.
I accidently wrote some code today that was like this[code]...
I immediately noticed the issue, but I had already hit the run button. It compiled successfully, I ran it through to the section and it threw an exception.
You can't do this in C#, it gives a compile error "cannot convert from 'int?' to 'int'".
Is there an 'Option Explicit' type switch that I can turn on to ensure that this sort of error does not occur again?
The issue is when I try to add a new item to the ArrayList with the following code, it gives me an error:
vb Private Sub btnLabelAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLabelAdd.Click
Dim result As String = InputBox("New Filter Label:", "Label List")
[CODE]................
Object reference not set to an instance of an object.
I'm not really sure what I'm supposed to be doing with this. It's a new setting I just added and it's empty, so I'm not sure if that has anything to do with it or not. Anyone know what's going on and what needs to be done to get it to accept a value and not want to be "initialized"?
I have recently gotten my hands on a free, open-source IMAP connection API.So far, I have been successful in creating a connection to one of my accounts.Where I'm getting stuck is retrieving folders and/or emails from those folders.Does there happen to be anyone here that is familiar with this API, or even Gmail (particularly the folder structure for IMAP)?
If not, here is a link to the DLL that is listed on sourceforge and the company's website that created it (if you feel like testing):
Koolwired
Sourceforge - Koolwired API
I have created a test account so feel free to use the code below without worrying about username/password issues; I'll just delete it when I'm done with it.Here is the code I have made so far for making a connection:
Dim gSession As New Koolwired.Imap.ImapConnect("imap.gmail.com", 993, True)
Dim gAuthenticate As New Koolwired.Imap.ImapAuthenticate(gSession, "imap_test@serysoft.com", "imap_test")
Try
[code]....
When I run that code, I get an error that states:System.NullReferenceException: Object reference not sent to an instance of an object. (The bold line in the above code).
Now, I'm not sure exactly what that means. Does that mean it tried to access the server and "INBOX" doesn't exist so it gets returned a NULL value? Or is it possibly the coding itself?Maybe the Gmail folder system is weird due to the fact they use labels (even though from what I have read online, the labels act as the folders in the IMAP system).
What is the problem in below code.
d Public Sub filltextbox(ByVal dlist As String) Dim tb As TextBox = CType(Page.FindControl(dlist), TextBox) tb.Text = "hello" End Sub
Error : Object reference not set to an instance of an object.
look after the error i'm having.
module1.vb
Imports System.Data.SqlClient
Module dbconn
[code]....
I create one function to run any select query. and return the OdbcDataReader type.But some time if there is no data it through error : Object reference not set to an instance of an object I need to know how i can control if there is no data.
Public Function Select_From_AnyTable(ByVal sqls As String, ByVal ConStr As String) Dim conn As OdbcConnection conn = New OdbcConnection(ConStr) Dim cmd As OdbcCommand = conn.CreateCommand() conn.Open() cmd.CommandText = sqls Dim reader As OdbcDataReader = cmd.ExecuteReader While reader.Read() Return reader End While conn.Close() End Function Dim ei As OdbcDataReader = Select_From_AnyTable("SELECT loginname from usertable limit 1", conStr) msgbox(ei.item("loginname "))
If there is data it work well but if no record found it through the error.
Is there a way to convert a DataGridViewRow object to a DataRow object?
View 2 Repliesi have drawn on a e.graphics object and now want to transfer the drawn stuff onto a bitmap object how can i do this?
View 2 RepliesLike every other program that you make when you code a button to open the next form it should open right. Well not in my case. I don't understand the problem that Visual Basics is not seeing my next form that I'm trying to open. When its in the Solution Explorer plain as day. Error below.An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object.show is not set to a object. All its doing is opening the next form. Ive use this code over an over. Now its giving me this C.O.S. error.
View 27 RepliesBasically all I am trying to do is to insert data entered in a text box(description) on the application form into database(sql2008) in vb.net. The vb code I wrote is below:
vb.net
Protected Sub Save_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Save.Click
Dim note As String = Description.Text
[code]....
However when I click on save button, I get following message:
System.NullReferenceException: Object reference not set to an instance of an object.
What in this code might be causing this??This part of the code is Hilighted as causing the error.
My.Settings.Item(Holiday_" & i) = DirectCast(Me.Controls("ComboBox" & i.ToString), ComboBox).SelectedItem
Public Sub btn_Update_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
[code].....
I am trying to clear a dataset in case it has some data already in so that I can add data to it to search a database, but when I run the program and get to the point that it tries to clear the dataset I get this error message "Object reference not set to an instance of an object", here is my
dtasetUser.Tables("tblUsers").Clear()Also I get an error "The 'Microsoft.ACE.OleDB.12.0' provider is not registered on the local machine" when trying to fill the same dataset, on searching I have found it is because I am trying to open a 2010 Access document in VB08, but I have no idea how to remedy this and any instructions I have seen make no sense to me, so I would like help with that too please.
I am able to populate an object and output everything. How do I remove say the name2 object?
la.Remove(Logins("name2")) doesn't seem to work.
Private Sub btnListArray_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnListArray.Click
[code]....
I'm trying to make a search textbox bring up certain records in a DataGrid. This is my code for that function:
Public Function Find(ByVal StrSearchString As String) As Boolean
DataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect
Dim intcount As Integer = 0
For Each Row As DataGridViewRow In DataGridView1.Rows
[code]....
The problem comes on this line:
If DataGridView1.Rows(intcount).Cells(0).Value.ToString = StrSearchString Then
I can't figure out what the unhandled exception is. Any ideas? I'm sure it's something very simple I'm overlooking.
I have: Dim nVar1 As Long?Dim nVar2 As Long?Dim nVarSum As Long?nVar1 = Nothing nVar2 = 5 nVarSum = nVar1 + nVar2 I would prefer the result to end with nVarSum being 5, instead of Nothing. I understand if you add something to an unknown value, you will end up with "somthing + unknown" or x+5 will always equal "x+5" not "5" because you are still carrying around that unknown "x". However, how can I effectively treat an unknown or Nothing as a zero for the purposes of addition in this case?(What is basically happening is that the end user is sending us a data file, this code parses that file and then sums together about 15 fields. If the user leaves those fields blank instead of assigning a zero to them, I need to treat it as if it was a zero for this one addition operation, but all the rest of the code needs to continue seeing it as a Nothing value since the user did not ACTUALLY submit zero... they submitted blank or nothing)
View 3 Replies