Trying to build a MySQL Database application using a Class object.

Getting Started
1

Because a Class will be available to my entire application, I want to connect to a MySQL Server using a Class object.

I am new to Xojo, so I borrowed the class from an example provided from another Xojo member from this forum, but the member’s example provided no other code for the application.

The Class object is named “dbs”, with no super.

Within the dbs class, there is a Method named “Constructor”.

This is the code for the method Constructor:

Constructor(Host As String, Port As Integer, UserName As String, Password As String, DBName As String, KeepAlive As Integer)
mDB = New MySQLCommunityServer
mDB.Host = Host
mDB.Port = Port
mDB.UserName = UserName
mDB.Password = Password
mDB.DatabaseName = DBName

mKeepAlive = New Timer
mKeepAlive.Period = 15 * 60 * 1000
AddHandler mKeepAlive.Action, AddressOf KeepAlive

#If DebugBuild Then
mDB.Host = “portal.axisdirect.co.nz”
mDB.Port = 6033
#endif

If mDB.Connect Then
mKeepAlive.Period = KeepAlive
mKeepAlive.Mode = Timer.ModeMultiple
Else
Break
End If

In my application, I have a Public Property: MyDB As dbs
An event in a window in the app has the following code:

Dim sHost As String, sUserName As String, sPassword As String, sDBName As String, intPort As Integer, intKeepAlive As Integer

sHost = “127.0.0.1”
sUserName = “root”
sPassword = “”
sDBName = “test”
intPort = 3306
intKeepAlive =1

Dim MyDB As dbs

MyDB.Constructor (sHost, intPort , sUserName, sPassword, sDBName, intKeepAlive)

When I run the code, I get a NilObjectException, but I do not know why. Any help would be appreciated.

John

2

Your code:

[code]Dim MyDB As dbs

MyDB.Constructor (sHost, intPort , sUserName, sPassword, sDBName, intKeepAlive)
[/code]
Should be:

[code]Dim MyDB As NEW dbs

’ MyDB.Constructor (sHost, intPort , sUserName, sPassword, sDBName, intKeepAlive) <-- Not needed.
[/code]
The Constructor is automatically called with the NEW command.

3

Simon,

Thank you for your reply.
When I change my code as you indicate, I now get a different error “Not enough arguments: got 0, expected 6”

John

4

Oops!

Try:

[code]Dim MyDB As New dbs(sHost, intPort , sUserName, sPassword, sDBName, intKeepAlive)

’ MyDB.Constructor (sHost, intPort , sUserName, sPassword, sDBName, intKeepAlive) <-- Not needed.[/code]
My error, sorry.

5

Thank you, Simon, that worked!

John