c＃multiforms DataSet

Question

On the first form I have:

var dsUni = new DataSet();
dsUni.ReadXml(pathDesc);
frm02.dgv02.DataSource = dsUni.Tables[0];
frm02.ShowDialog();
dsUni.WriteXml(pathDesc); //this line is in the frm02.ClosingEvent

So, on the secondForm I need the same DataSet(dsUni) to writeXml from changed dgv02.
But, i got the errors:
The name 'dsUni' does not exist in the current context
Please, give me a solution for this case.

Answer 1

The error is telling you that the second form doesn't have a variable named dsUni defined. You need to define it, such as var dsUni = new DataSet(); did on the first form. While you have passed the data itself along via the line frm02.dgv02.DataSource = dsUni.Tables[0]; , the variable named dsUni is local to form1, so form2 doesn't know about it. If you want to access that dataset under the name dsUni , you must expose it so form2 can directly access it, or create a new local variable by that name on form2 and load it with your desired data (very inefficent, unless you just use a pointer back to form1's dsUni).

If you create a new variable on form2 called dsUni , don't forget to load it with your desired data, as it will start out empty.

Answer 2

Don't do this it's just asking for it.

Huge amount of technical debt justwaiting to happen.

There's a few ways to do it better, but this one you can build on.

Create a little class eg

public class MyData()
{
   public Dataset MyDataset {get; private set;}

   // add constructor and all methods related to the dataset here. 
}

Then just create one in Form1, do what you have to do and pass it to form2, either as a property or in the constructor.

If it's common and it's not totally trivial, create a common something, put all the methods that relate to it in there and then use it. As soon as you start with the form2 depends on form1 manouevre you might as conserve energy and just jam a biro up your left nostril as hard as you can, the headache will be similar.

An interface will be better, but that's the next lesson.