How can I access a Dataset from 2 different foms

[dougconran]

How can I read data in a dataset (created using the Data Adapter Wizard) declared in another form?

I am using the Data Adapter Wizard to set up a connection to an Access database, one table of which I then display in a DataGrid.

This DataGrid serves 2 purposes (1) to provide a means of drilling down to a detail screen when the user clicks on a cell in the first column and (2) to provide a means of multi-selecting a number of rows by clicking on a checkbox in the last column.

Although the datagrid is populated from the dataset I need to manually add the last, checkbox, column as it is not part of the access table. The only way that I have found of making this writeable is to use the Data adapter wizard and then do a dataset.tables(0).columns.add(...). Manually declaring the connection, adapter and dataset seems to force everything to Readonly, even if I explicitely set readonly = false.

Unfortunately, the dataset etc need to be global so that I can read it from the drill down form.

How do I declare an OleDBConnection, OleDBDataAdapter and Dataset to be global when they are created by the Data Adapter Wizard.

TIA

Doug

 

[akohli]

Hi,

I am totally guessing here since have never used the wizards provided in VS.NET. Here goes anyway - I am sure that using the wizards dumps a ton of code in the designer generated code section. Check the access modifiers for the objects that are created, change those to public.

HTH

amit

actually, just fired up a form and added an adapter and a dataset using the wizard, the access modifier is friend i.e. class level. DO you get a compiler error if you try to use the objects?

 

[dougconran]

I don't get a compiler error but the objects are not visible from a different form.

I am told that I should declare a dataset along hte following lines:-

dim ds as application.dataset1 = form1.datasetname

The trouble is that when I type in the 'form1.' a list of selections is displayed which seem to be to do with form1 as a whole rather than the objects in the form.

I guess that what I need to be able to do is to declare the dataset (and other things?) in form1 in such a way that they are visible in other forms using the above syntax - but how do I do that? Especially if I am using the wizard which, for some reason I've yet to fathom, it seems I do?

TIA

Doug

 

[kristof]

Hi,

Could use a public function within form1 like this:

Public Function GetDataSet()
  return dsForm1
End Function

Which you then call within the other form like this

dim dsOtherForm as DataSet = form1.GetDataSet()

That way when working with dsOtherForm, you will actually be working with the dsForm1 dataset, so any changes you make, will have effect for dsForm1.

Hope that helps,

Kristof

 

[kristof]

Oops, the function should have a return type ofcourse:

Public Function GetDataSet() as DataSet
  return dsForm1
End Function

 

[dougconran]

Thanks for this - but I'm still getting an error.

This is what I have in Form1 (called nr1_weld_summary)

    Public Function GetDataSet() As DataSet
        Return ds
    End Function

and this in Form2

        Dim dr() As DataRow
        Dim ds As DataSet = nr1_weld_summary.GetDataSet()

but when I type in the full stop after nr1_weld_summary the list of options does not include GetDataSet and when I force it in and then compile I get the following error:

Reference to a non-shared member requires an object reference.

If I declare the GetDataSet function as Shared then I get the following error for the line 'Return ds'

Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class.

and I have absolutely no idea what it means

So I'm still no further ahead - just balder!

TIA

Doug