Reference: Object reference not set to an instance of an object.

[Lost User]

Not in the ConnexionMysql class, I hope? The ConnexionMysql object needs to exist (new ConnexionMysql) before you call any non-static methods. I suggest you create the connection when it's needed, using the standard pattern; create a IDbConnection, create an IDbCommand, open, execute.

Bastard Programmer from Hell :suss:

[MemberDotNetting]

the connexionmysql is a static class witch contain the connection with database with the method"getconnexion" and function "getdatabasenames"

[Lost User]

Can you post the code of that method? That's where the error will be originating from :)

Bastard Programmer from Hell :suss:

[Pete OHanlon]

He should be debugging it, not posting it. It's not a difficult thing for him to do.

*pre-emptive celebratory nipple tassle jiggle* - Sean Ewington

"Mind bleach! Send me mind bleach!" - Nagy Vilmos

CodeStash - Online Snippet Management | My blog | MoXAML PowerToys | Mole 2010 - debugging made easier

[MemberDotNetting]

combdb.SelectedItem=null

[Pete OHanlon]

And there's your problem. If this is null, don't attempt to execute the code.

*pre-emptive celebratory nipple tassle jiggle* - Sean Ewington

"Mind bleach! Send me mind bleach!" - Nagy Vilmos

CodeStash - Online Snippet Management | My blog | MoXAML PowerToys | Mole 2010 - debugging made easier

[Lost User]

I don't see anything difficuly in creating a connection, but apparently, it is. I could say that he should be reading the documentation, but most people don't :)

Bastard Programmer from Hell :suss:

[MemberDotNetting]

I stick a breakpoint on the line that's raising the exception, and i get combobox item=null

[MemberDotNetting]

i Stick a breakpoint on the line combdb.ItemsSource = ConnexionSqlServer.GetDataBasesNames() wich is the method that fill the combobox, i get the exception on combobox although the method returns the names of the database when I test every single button while it works but the problem is when I migrate from one button to another

[MemberDotNetting]

i Stick a breakpoint on the line combdb.ItemsSource = ConnexionSqlServer.GetDataBasesNames() wich is the method that fill the combobox, i get the exception on combobox although the method returns the names of the database when I test every single button while it works but the problem is when I migrate from one button to another

[Lost User]

When you update the contents of a ComboBox, you cannot always assume that the SelectedIndex will get set to a valid item; often it winds up set to -1; depending on the circumstances. You need some defensive code; e.g.

if ( cb.Count > 0 ){
if ( cb.SelectedIndex < 0 || cb.SelectedIndex >= cb.Count ) {
cb.SelectedIndex = 0;
} else {
... // Bail out.
}
}