Conversion Error When Trying To Call An Image If Database Value Is NULL.
Feb 4, 2012
I am trying to load an image onto a web form depending on the image's URL path inside a database. I can get this to work, however I am trying to display a dummy image incase the record in the database has no image and the column is NULL.
Below is the code that I imagined would work but I receive an error:
Conversion from type 'DBNull' to type 'String' is not valid.
'// Load Item Image in imgMenuItem Image Control //
If (Not IsDBNull(Rdr("img_url"))) Then
imgMenuItem.ImageUrl = Rdr("img_url")
[Code].....
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Jul 22, 2009
Is their a more elegant way to assign a space to a value, if a database call returns null for a data set column? I am doing the following check which is pretty tedious:
If (ds.Tables("employee").Rows(0).Item("txtNamePrefix").IsDBNull(0)) Then
txtNamePrefix.Text = ""
Else
txtNamePrefix.Text = ds.Tables("employee").Rows(0).Item("txtNamePrefix")
End If
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Aug 23, 2011
I have a database and I'm storing images in it along with a person's name, and other attributes. I've databound my listview with a stored procedure. I want to know how I can display an icon on a row depending on if the record for that row has a picture or not for the person...I'm not sure how to accomplish this however with the templates in asp.net
EDIT:
Here is my template and the s where I'm hoping to put them.
<ItemTemplate>
[code].....
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Sep 2, 2010
I'm working on a form that allows to add new users to a users table in my Access database. The table only has 3 fields: user (string), password (string) and admin (boolean). user is the primary key. But when I run it and try to add, I get an error when casting the query to Double (?). I don't have any double variables or table fields, and I'm not trying to cast anything from or to double. So I have no clue about how to fix this. The code I'm using to insert (and it's working correctly on other forms and tables I have) is:
[Code]...
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Mar 4, 2012
I am trying not to become intimidated or give up.I created a simple database and added stored procedures to read the data on a Windows form using Visual Basic in VS 2010.First I tried the Data Grid Example and all worked, I was able to view the data using a connection string to call the Stored procedure.I have stepped it up a notch by trying to bind data to form controls and I am getting this error message when I try to navigate through the data.
System.NullReferenceException was unhandled
[code].....
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Apr 8, 2009
a user will enter a number, n, which ranges from 1 to 30. they will also enter a "P" or an "S" (sum or product). depending on which was selected, it will calculate the sum or product of the numbers from 1 to n.i'm having a conversion error on line 5 stating "Conversion from string "S" to type 'Double' is not valid." [code]
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May 19, 2010
Pulling a record from the DB and populating a list view but keep getting conversion from DBNull to Single is invalid (words to that effect). The code is below with bold highlighting where problem is and a bit more helpful description of error. I get this error: "Conversion from type 'DBNull' to type 'Single' is not valid." [Code]
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Sep 14, 2010
We are converting a large VB6 application to VB.net. The problem we have all over the code is the .NET converter did not "reorder" the "IF" and other statements in the code to stop execution when a DBNull value exists. For example, we have code like this all over the place.
"If rRow.Item("av_election_id") > 0 And (rRow.Item("Challenged") <> "SUSPD" Or IsDBNull(rRow.Item("Challenged"))) Then"
This causes a error when "rRow.Item("Challenged") is dbnull
The line of code below corrects this issue but we have thousands of lines of code to reorder and refactor.
If
dtAVVoterRow.Rows(0)("av_election_id") > 0
And (IsDBNull(dtAVVoterRow.Rows(0)("Challenged"))
OrElse dtAVVoterRow.Rows(0)("Challenged")
<> "SUSPD")
Then
creating a wrapper class or something to allow us to keep the first example of code above where it will not throw an error when encountering a Null value? I don't know if a wrapper that reordered the If statements, or captures the error but continues the execution somehow?
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Nov 6, 2009
I need to add multiple textboxes together and am using Cdbl, my problem is if i have an empty box then conversion can not work, so i have to put zero default in each Textbox, i really dont like they way that looks So i am looking for a way to to give an empty textbox a value of zero so the conversion will work
[Code]....
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Mar 11, 2010
[Code]...
'column' argument cannot be null. Parameter name: column
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Nov 18, 2011
I am running into a problem while attempting to to retrieve data from a database. One of the items is an iage and it's throwing an error when I try to convert the byte array to a bitmap.Here is what I have. The exception "Parameter is not valid." is being thrown when on the line bmpImage = New Bitmap(stream)
Private Sub GetCatList()
Dim strSelect As String
strSelect = "Select CategoryID, CategoryName, Description, Picture"
[code]....
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Aug 26, 2009
i tried to save image into my database, it saves without error but when i tried to check if it saves in mysql, the data about my picture id save, but the image i save return a value of 0.
[Code]...
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May 17, 2011
I connected to the Informix server using RazorSQL, created a stored procedure and tested it, getting the expected answer, so the procedure exists in the database in some form.
I then run the following code:
If ConnectToInformix() Then
Dim cmd As New IfxCommand("dc_routeHasOutstandingQuantity", conn)
cmd.CommandType = CommandType.StoredProcedure
[Code]....
This error does not occur when calling the stored procedure from a live SQL connection.
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Oct 20, 2011
I am trying to create a treeview in VB.net, the data has to be loaded from MSAccess 2010 database. When I try to run this program I get error : Argument Null Exception was unhandled, 'column' argument cannot be null and the program crashes. I have pasted the code as under:
Imports System.Data.OleDb
Public Class frmRating
Private Sub frmRating_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles
[code].....
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Mar 29, 2009
I am trying to utilize the access database, but I'm getting an error message: Value cannot be null. Parameter name: dataSet
[Code]...
That's the code I'm using, why I'm getting this error?
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Oct 15, 2009
Ive created one database Sql Server Compact Edition 2005, with one table ("Cliente") I know that I can created my database good, but i have a problem saving information since three textbox, in my table(With columns "Nombre" "Apellido" "Cliente". In my form there is a button save ("Guardar"). When I do click in my button appear the next message : "The column cannot contain null values. [ Column name = Nombre,Table name = Cliente ] " and happen the same with apellido and Id_Cliente. And this happen becouse my code cant save the information....
This is the code
Option Explicit On
Option Strict On
Imports System
Imports System.IO
Imports System.Data
[CODE]...
And the code for my button is:
Private Sub cmdguardar_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdguardar.Click
Dim myconnection As SqlCeConnection
Dim mycommand As SqlCeCommand
[CODE]...
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Mar 20, 2011
i need a windows program (on visual basic express) to convert a list of images to black and white. then to send it to a microcontroller via ethernet. i dont know anything about vb at the moment so simple explanations and code would be great. in the meantime i will try learning vb. but i need this program quick.
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Dec 30, 2009
I use following codes to display image from sql server. [code]...
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Jan 5, 2012
In my VB.NET application when I try to get the image location using picturebox.ImageLocation (path), it is returning null. I have to use that path string in filestream's parameter to open it. Since it is returning null, I couldn't open the file (image) in filestream. The following error is coming:
"Path cannot be null"
This is my code:
Dim path As String = Picturebox1.ImageLocation
Dim filestrm As FileStream = New FileStream(path, FileMode.Open)
Dim arry(filestrm.Length - 1) As Byte
filestrm.Read(arry, 0, filestrm.Length)
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May 3, 2012
I've got a little problem. I'm trying to choose a background for the program based on Settings, but I'm getting a Null Reference Exception and I don't know what I'm doing wrong. Here's the
[Code]...
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Aug 17, 2010
I am trying to implement image caching for a web application and I found some code on the Internet that implements an HttpHandler that does this. The code was in C# and since my web app is written in VB, I decided to convert the code to VB. I managed to convert everything except the following code (in bold):
public class FileExtensionCollection : ConfigurationElementCollection
{
public override ConfigurationElementCollectionType CollectionType
{
[CODE]...
From what I can understand, the two properties above provide a way to access the FileExtension collection either using an integer or a string index. My problem is that I do not know how to convert this in VB.
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Dec 22, 2010
The code that I will be posting here in this thread is about inserting image into MS Access database. I have a problem indicating an error saying "Parameter is not valid".
[Code]...
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Jul 8, 2009
So i am converting a metafile (EMF to be exact) to a jpeg or gif (doesn't matter as long as it's compatible with browsers) and when I do the conversion, all of the transparent pixels turn black. I have no idea how to do this in GDI+ but here is the method I am using to save the file:
Dim Img As System.Drawing.Imaging.Metafile = New System.Drawing.Imaging.Metafile(stream)
Img.Save(Server.MapPath("/FileName.gif"), System.Drawing.Imaging.ImageFormat.Gif)
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Feb 27, 2009
i am trying to find the loctaion of an item in an array but ecah time i run the for each next loop i get a null error. code follows:
[Code]...
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May 20, 2011
I keep getting the "Object reference not set to an instance of an object." error and it tells me to check if the pp(f, 0) object is null .... which I know it is not.[code]...
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Dec 31, 2009
I'm quite new to VB. I had open a VB6 file using VB express. Then some error arise after the conversion 1st error: Value of type 'Char' cannot be converted to 'Double' (Highlighted in Red)
Option Strict Off
Option Explicit On
Friend Class MainForm
Inherits System.Windows.Forms.Form
Private Const VendorID As Short = 6017
Private Const ProductID As Short = 2000
[Code]...
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May 25, 2011
I recently upgraded a VB 6 project to .net. I'm having a problem with this block of code:
Dim CtrlName As System.Windows.Forms.MenuItem
For Each CtrlName In Form1.Controls
'Some code here
[code].....
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May 7, 2010
I am getting the attached error when any cell in a row is empty. How to avoid this error and to accept the null values?
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May 2, 2010
I using ADO to get som values from a SQL DB one off the fields can have the value NULL And if i use:
txtinfo.Text = RS(
"info").value
Then i get an error.I have try with IS NULL - but that dosn't work
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Jan 4, 2010
Im trying to write code that will insert 'records' into an xml file, but everytime i click the button to make the changes to the XML file, it throws a null reference exception, ive gone through this code must be 100 times and cannot find what needs to be declared as 'new' as i know nodes can't be 'new' and the doc is 'new'
Imports System.Xml
Public Class frmuseradmin
[code]......
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