Using Global / Session variables in a Windows Forms application

[Sandy]

My background is web based. I am attempting to write a Windows
application and I am finding some simple things difficult.

Currently I am trying to find out how to store information session
wide. In the web you have session state and you can add variables or
objects to it. They remain in existance until the session ends.

How could I do that for a windows forms application?

For example: a modal form is launched to log in, I do a database
lookup, confirm this is a valid user. I would like to set up my 'User'
object (a class that I have created) and assign values to it based on
the person who just logged in. I then want to be able to access that
object from my other forms.

I don't know how. (I could do this for the web, but this is Windows,
target is Win2k or WinXP if it matters).

[Sandy Murdock]

'CurrentUser.Ge tInstance

is just not available. I have used the code as documented above:

<code>
Public NotInheritable Class CurrentUser
Inherits User

Shared myInstance As CurrentUser

Public Shared Function GetInstance(ByV al strValue As String) As
CurrentUser
If myInstance Is Nothing Then
myInstance = New CurrentUser)
End If
Return myInstance
End Function

End Class
</code>

but GetInstance is not accessable from anywhere.

This looks pretty simple, I don't see where I have gone wrong, but it
certainly does not work.

Sandy Murdock MCP

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[Herfried K. Wagner [MVP]]

"Sandy Murdock" <sa***@murdocks .on.ca> schrieb:

'CurrentUser.Ge tInstance

is just not available. I have used the code as documented above:

<code>
Public NotInheritable Class CurrentUser
Inherits User

Shared myInstance As CurrentUser

Public Shared Function GetInstance(ByV al strValue As String) As

Remove the 'strValue' parameter, then it should work...

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>

[Sandy Murdock]

I have changed:

Public Shared Function GetInstance(ByV al strValue As String) As
CurrentUser

to

Public Shared Function GetInstance() As CurrentUser

The function is still not accessible.

Sandy Murdock MCP

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[Herfried K. Wagner [MVP]]

"Sandy Murdock" <sa***@murdocks .on.ca> schrieb:

Public Shared Function GetInstance() As CurrentUser

The function is still not accessible.

Add the code below to your project:

\\\
Public NotInheritable Class Settings
Private Shared m_DefInstance As Settings

Private m_UserName As String

Private Sub New()
'
End Sub

Public Shared Function GetInstance() As Settings
If m_DefInstance Is Nothing Then
m_DefInstance = New Settings
End If
Return m_DefInstance
End Function

Public Property UserName() As String
Get
Return m_UserName
End Get
Set(ByVal Value As String)
m_UserName = Value
End Set
End Property
End Class
///

You can access the settings in the project that contains the class with
'Settings.GetIn stance()'.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Rob Nicholson]

> My background is web based. I am attempting to write a Windows

application and I am finding some simple things difficult.

It's usually the other way around :-) I come from a traditional client
application environment and I'm finding I'm having to re-think a lot of the
ways you do things like global variables stored in the session.

Come the revolution, we'll be back full circle to full-blown client apps
that happen to be internet hosted and so benefit from "access anywhere" and
"zero rollout/footprint". Mark my words.

Cheers, Rob.

[Sandy]

"Herfried K. Wagner [MVP]" <hi************ ***@gmx.at> wrote in message news:<#M******* *******@TK2MSFT NGP09.phx.gbl>. ..

"Sandy Murdock" <sa***@murdocks .on.ca> schrieb:

I am not clear on where or how to use:

Simply use 'CurrentUser.Ge tInstance().Nam e = "Bla"'.

I have tried a few places and modifications but none seems to be a valid
command. Is that a C# style command?

Sorry for the other messages -- my keyboard temporarily didn't work for some
reasons.

You can use the code above everywhere in your code after you added the
Singleton class to your project. '.Name = "Bla"' is only a sample that
presumes that you have added a 'Name' property to the 'CurrentUser' class.

I have been away from this program for some time (surgery, nothing
life threatening but I have been off work.) so I have now done the
following:

Created the class as outlined:

Public NotInheritable Class Settings

Private Shared m_DefInstance As Settings

Dim m_UserName As String

Private Sub New()
'
End Sub

Public Shared Function GetInstance() As Settings
If m_DefInstance Is Nothing Then
m_DefInstance = New Settings
End If
Return m_DefInstance
End Function

Public Property UserName() As String
Get
Return m_UserName
End Get
Set(ByVal Value As String)
m_UserName = Value
End Set
End Property
End Class

Then in my program I do this:

Sub SetFormToUser(B yVal objUser As User)

Dim objThisUser As Settings
objThisUser.Get Instance()

MessageBox.Show (objUser.FirstN ame)
objThisUser.Use rName = objUser.FirstNa me

Me.UserID = objUser.UserID
Me.UserPwd = objUser.Pwd
Me.FirstName = objUser.FirstNa me
Me.LastName = objUser.LastNam e
Me.UserTypeID = objUser.UserTyp eID
Me.UserType = objUser.UserTyp e
End Sub

This code is on the actual login form. I set the properties for the
form (which ultimately I hope to do away with) and, in theory, set the
the UserName property from the Settings Class (called objThis user).

Here is the problem;

I can confirm that objUser.FirstNa me has a value, but when I try to
run the code I get an error: "Object reference not set to an instance
of an object."

I believe this is caused by the objThisUser (Settings) object,
UserName property not existing? There is some strange thing happening
here; I know that I am assigning a value, but I am getting the 'Null'
message.

Do you have any idea what might cause that?