Here is my code I get the error on:
Imports ADFactory
Public Class Salary
Inherits Salary_Datalayer
Protected _AD As New ADFactory.ADFactory
Protected Sub Page_Load(...)Handles Me.Load
_user = "username"
sDealer = _AD.GetUserCompany(_user)
It states that Protected _AD As New ADFactory.ADFactory is the line throwing the exception. I've looked online and read and changed it several times, declared 'New', am I missing something simple?
PatFromCanada was correct, my ADFactory was the problem. I didn't properly initialize a connection string within the reference, thus always throwing a nullexception, which apparently, I run into quite often in my questions. Thanks PatFromCanada!
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enter code hereI am trying to assign a value to label in a Master Page using vb.net (not my first language-lol). I have followed info from these two references on how to access content from masterpage:
1.[https://msdn.microsoft.com/en-us/library/c8y19k6h(v=vs.90).aspx][1]
2.[nullreferenceexception was unhandled by user code in Master Page
I am getting Null Reference Exception on BUT ONLY when I try to call the method I created for it from another class. It works fine when I call it from the same class the method is in. I wrote a method from the starting page/class, WebForm1:
Public Sub PageIdentity(ByVal pageId As String)
' Gets a reference to a Label control inside a ContentPlaceHolder
Dim mpContentPlaceHolder As ContentPlaceHolder
'Dim mpTextBox As TextBox
Dim mpLabel As Label
mpContentPlaceHolder = CType(Master.FindControl("MainContent"), ContentPlaceHolder)*'Null Reference Exception here*
If Not mpContentPlaceHolder Is Nothing Then
mpLabel = CType(mpContentPlaceHolder.FindControl("lblPageIdentifier"), Label)
If Not mpLabel Is Nothing Then
mpLabel.Text = pageId
End If
End If
End Sub
when I call this function from another class in page load like this it throws null ref ex:
Dim oWebForm1 As WebForm1 = New WebForm1()
oWebForm1.PageIdentity("SomeText")
I must be doing something wrong in creating the instance? I tryed writing it as a Public Shared Function first but that created other problems. Can anyone help?
UPDATE: #Joey I replaced the commented line of code below as you suggested and put the sub in the master page code behind, Site1.Master.vb:
'mpContentPlaceHolder = CType(Master.FindControl("MainContent"), ContentPlaceHolder)
mpContentPlaceHolder = CType(Me.FindControl("MainContent"), ContentPlaceHolder)
I also ensured that the page directive on other pages included:
<%# MasterType VirtualPath = "~/Site1.Master" %>
On a test page, I called the sub like so:
Dim _SiteMaster As MasterPage = TryCast(Me.Master, MasterPage)
_SiteMaster.PageIdentity("SomeText")
I am getting blue squiggly line error, message: "PageIdentity is not a member of System.Web.UI.MasterPage"
The Master page inherits like this:
Public Partial Class Site1
Inherits System.Web.UI.MasterPage
The page calling the sub inherits like this
Public Class WebForm1
Inherits System.Web.UI.Page
Since you require the PageIdentity subroutine to be somewhat global you can move it into your master page. The master page can then be called by any page that references it. Use the following code on any page to call the PageIdentity routine:
Dim _SiteMaster As Site1 = TryCast(Me.Master, Site1)
_SiteMaster.PageIdentity("SomeText")
How can i convert this code to VB.net
public void SetBooks(IEnumerable<Book> books)
{
if (books == null)
throw new ArgumentNullException("books");
new System.Xml.Linq.XDocument(books).Save(_filename);
}
in http://converter.telerik.com/ it says:
Public Sub SetBooks(books As IEnumerable(Of Book))
If books Is Nothing Then
Throw New ArgumentNullException("books")
End If
New System.Xml.Linq.XDocument(books).Save(_filename)
End Sub
But visual studio says "Syntax error." because of "New"
What is the keyword for this situation, i searched on Google but no result.
Actually, you can do it in one line with the Call keyword
Call (New System.Xml.Linq.XDocument(books)).Save(_filename)
You cannot initialize an object and use it in one statement in VB.NET (as opposed to C#). You need two:
Dim doc = New System.Xml.Linq.XDocument(books)
doc.Save(_filename)
In C# the constructor returns the instance of the created object, in VB.NET not.
Sorry, this can be a basic question for advanced VB.NET programmers but I am a beginner in VB.NET so I need your advice.
I have a web application and the login is required for some specific pages. To check if the user is logged in, the old programmer used this technique:
Dim sv As New WL.SessionVariables(Me.Context)
If Not (sv.IsLoggedIn) Then
Response.Redirect(WL.SiteMap.GetLoginURL())
End If
Well, I have to use this Logged In checking in a handler done by me and I tried this:
Public Class CustomHandler
Implements System.Web.IHttpHandler, IReadOnlySessionState
Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
Dim sv As New WL.SessionVariables(context)
If Not (sv.IsLoggedIn) Then
context.Response.Write("No access unless you're the CEO!!!" & sv.IsLoggedIn)
ElseIf sv.IsLoggedIn Then
DownloadFile(context)
Else
End If
End Sub
//other code
End Class
Well, the "is logged in" checking is always false (even after I login) and I think it's an issue with the context. So all the other pages works fine with logging checking but this handler have this specific issue.
Can you guys give a helping hand?
UPDATE:
The logged in is done trough this method:
Public Sub SetCreditialCookie(ByVal accountID As Integer)
Me.AccountID = accountID
m_context.Session.Item("loggedInAccount") = accountID
m_context.Response.Cookies.Add(New System.Web.HttpCookie("account_id", CStr(m_context.Session.Item("account_id"))))
m_context.Response.Cookies("account_id").Expires = DateTime.Now.AddDays(5)
End Sub
and to check it it's logged in, this method is called:
Public Function IsLoggedIn() As Boolean
If Not m_context.Session.Item("loggedInAccount") Is Nothing And Me.AccountID = m_context.Session.Item("loggedInAccount") Then
Return True
Else
Return False
End If
End Function
UPDATE 2:
- debugging the code shown that there were multiple kind of logins and I was checking the wrong one with the session.
Due to the use of IReadOnlySessionState, is it possible that the SessionVariables class attempts in some way to modify the Session, which in turn causes an error (possibly handled and not visible to you).
If this is the case it could mean that the IsLoggedIn property is not correctly initialised, or does not function as expected?
Do you have access to the code for the class. If so, try debugging it to see what is happening.
I always get an exception when I try to switch between different forms in my program. Maybe you will help me to solve this issue. Here is the exception message:
Control.Invoke must be used to interact with controls created on a separate thread
I have attached the forms to very nice variables and this problem occurs when I try to use command like MyForm.Show().
It does not happen when the forms are not attached to variables, but then I have collosal problems with refreshing the textboxes and stuff.
Hope to hear you soon!
edit;
I have 4 different forms. When I load the main module and main form, in the Sub (...) Handles MyBase.Load I execute the following code:
In module:
Public StartupForm As frmStartup
Public RegularForm As frmRegularUse
Public LoginForm As frmLogin
Public PasswordForm As frmPassword
Public SettingsForm As frmSettings
In main form:
RegularForm = Me
StartupForm = frmStartup
LoginForm = frmLogin
PasswordForm = frmPassword
SettingsForm = frmSettings
This is the aproach I worked out to get the full control over refreshing the forms. It is a program for Motorola Scanner with Windows CE. Now, for example, when I enter the correct password in LoginForm, I want to switch to the RegularForm. When I try to use RegularForm.Show() or RegularForm.ShowDialog or RegularForm.BringToFront(), I get an exception. When I try to call the form with the frmRegularUse.Show() I can call the form, but it is being created in a different thread, I believe, so I loose control over it (when I try to put something from the keyboard, there is no response).
I doubt the forms are getting created in a different thread, but if they are then STOP, go back, and fix that. All of your forms should be created and accessed from the main GUI thread. Secondly, I don't think you "newed" the forms. You need something like this:
StartupForm = New frmStartup
RegularForm = New frmRegularUse
LoginForm = New frmLogin
PasswordForm = New frmPassword
SettingsForm = New frmSettings
Actually, what I did is:
Still I have the same code in the main module, which is:
Public StartupForm As frmStartup
Public RegularForm As frmRegularUse
Public LoginForm As frmLogin
Public PasswordForm As frmPassword
Public SettingsForm As frmSettings
I managed it to work in the simpliest possible way. For example - I run the Login form, and execute the following code (long story short):
LoginForm = Me
frmRegularUse.ShowDialog()
I jump to the frmRegularUse form, where, once again, I execute:
RegularForm = Me
frmPasswordForm.ShowDialog()
And so on...
I made some tests and it works quite okay. Tomorrow I will try to make it a little bit more sophisticated. ;-)
The following code has two flaws, I can't figure out if they are bugs or by design. From what I have seen it should be possible to write back to the app.config file using the Configuration.Save and according to http://www.codeproject.com/KB/cs/SystemConfiguration.aspx the code should work.
The bugs are shown in the source below and appear when you try to set the property or save the config back out.
Imports System.Configuration
Public Class ConfigTest
Inherits ConfigurationSection
<ConfigurationProperty("JunkProperty", IsRequired:=True)> _
Public Property JunkProperty() As String
Get
Return CStr(Me("JunkProperty"))
End Get
Set(ByVal value As String)
' *** Bug 1, exception ConfigurationErrorsException with message "The configuration is read only." thrown on the following line.
Me("JunkProperty") = value
End Set
End Property
Public Sub Save()
Dim ConfigManager As Configuration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None)
' The add / remove is according to http://www.codeproject.com/KB/cs/SystemConfiguration.aspx
ConfigManager.Sections.Remove("ConfigTest")
' *** Bug 2, exception InvalidOperationException thrown with message "Cannot add a ConfigurationSection that already belongs to the Configuration."
ConfigManager.Sections.Add("ConfigTest", Me)
ConfigManager.Save(ConfigurationSaveMode.Full, True)
End Sub
Public Shared Sub Main()
Dim AppConfig As ConfigTest = TryCast(ConfigurationManager.GetSection("ConfigTest"), ConfigTest)
AppConfig.JunkProperty = "Some test data"
AppConfig.Save()
End Sub
' App.Config should be:
' <?xml version="1.0" encoding="utf-8" ?>
'<configuration>
' <configSections>
' <section name="ConfigTest" type="ConsoleApp.ConfigTest, ConsoleApp" />
' </configSections>
' <ConfigTest JunkProperty="" />
'</configuration>
End Class
I'd like to do it this way so that on the first run of the app I check for the properties and then tell the user to run as admin if they need to be set, where the UI would help them with the settings. I've already 'run as admin' to no effect.
Your code doesn't really make any sense. I took your example code and turned it into a simple example that works. Please note this is not best practise code, merely an example to aid you on your journey of learning the configuration API.
Public Class ConfigTest
Inherits ConfigurationSection
<ConfigurationProperty("JunkProperty", IsRequired:=True)> _
Public Property JunkProperty() As String
Get
Return CStr(Me("JunkProperty"))
End Get
Set(ByVal value As String)
' *** Bug 1, exception ConfigurationErrorsException with message "The configuration is read only." thrown on the following line.
Me("JunkProperty") = value
End Set
End Property
Public Overrides Function IsReadOnly() As Boolean
Return False
End Function
Public Shared Sub Main()
Dim config As Configuration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None)
Dim AppConfig As ConfigTest = config.GetSection("ConfigTest")
AppConfig.JunkProperty = "Some test data"
config.Save()
End Sub
End Class
This code will open the config file, modify the attribute JunkProperty and persist it back it the executable's configuration file. Hopefully this will get you started- it looks like you need to read about the configuration API a bit more.
I've used the API to create configuration sections for large scale enterprise apps, with several 1000 of lines of custom hierarchical config (my config was readonly though). The configuration API is very powerful once you've learnt it. One way I found out more about its capabilities was to use Reflector to see how the .NET framework uses the API internally.
Maybe you don't know Portuguese or c# but this is you want http://www.linhadecodigo.com.br/Artigo.aspx?id=1613
using BuildProvider from asp.net
After loading a configuration it is readonly by default, principally because you have not overriden the IsReadOnly property. Try to override it.
¿Is there something that prevents you from using a setting?
Looks like it is not possible by design. App.config is normally protected as it resides along with the app in the Program Files directory so must be amended at installation time by the installer.
Pity really, I'd like the app to have settings that an admin can set.
Sorry if I didn't understand your case, but yes, you can change App.config at runtime.
Actually, you will need to change YourApp.exe.config, because once your app is compiled, App.config contents are copied into YourApp.exe.config and your application never looks back at App.config.
So here's what I do (C# code - sorry, I still haven't learnt VB.Net)
public void UpdateAppSettings(string key, string value)
{
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
foreach (XmlElement item in xmlDoc.DocumentElement)
{
foreach (XmlNode node in item.ChildNodes)
{
if (node.Name == key)
{
node.Attributes[0].Value = value;
break;
}
}
}
using (StreamWriter sw = new StreamWriter(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile))
{
xmlDoc.Save(sw);
}