calling related form's method(s)

Classic Servoy
1

I have a table (T1) with a related table (T2);

a form for displaying things from T1;

on the form, I have a related tab panel, for displaying
fields from table T2.

I’ve been working on this for a day or so, and everything
has been working as expected; as I move thru records in
table T1, I can see related records in the tab panel for
table T2. A control outside of the tab panel lets me move
thru these related records.

Suddenly, I’m getting errors as I move thru records in table T1.
I have a method in the main form connected to the
onRecordSelection event; this method calls a method in the
tab panel with a statement like: “forms.MyRelatedForm.RecordChange()”

It’s in this method that I’m getting errors telling me that my fields
don’t exist - sometimes.
(I can’t get it to happen as I’m writing this, so I don’t have the
exact error message)

Is it ok for the main form to call a method in a related form? And
shouldn’t that method be able to access the (related) table’s fields?

thanks in advance.
rm.

2

Hi Robert,

Can you mail me a sample solution?

3

hi maarten;

the solution i’m working with is quite large;

i solved the problem by placing the following lines
at the beginning of each method that runs in the
related table:

if (controller.getMaxRecordIndex==0)
return;

it appears that my problem is that i’m calling methods
in the related table when there are no related records.

4

Hi Robert,

In general ALWAYS use this IF before you do something with related records:

if(relationname)
{
   //there are related record - so continue
}

This will make sure the relation is valid (i.e. there are records).

Hope this helps

5

additional note:

Safest way to check for child records is:

databaseManager.hasRecords(foundset/relationName)

if(relationname)

will only check if the relation is defined in your solution,
and NOT if there are any child records.

6

sounds good. thanks for the responses everybody!