Dynamics AX 2012 has a nice class called RecordSortedList, which can be used to create a list of records from a database table. It can be useful when you need to pass a list of records into a method, or return a list of records from a method.
I honestly haven’t used it that often, but I had a case today where I thought it would be perfect. I had a method that currently returns a single record from a table, but that needed to be changed to return a short list of records.
I wrote some code to insert records into the list, then another bit to loop through the list and do something with the records in it. I was puzzled that, while I was definitely inserting multiple records into the list, I was only getting a single record back out. After some trial and error, I discovered that the methods to retrieve records from the list don’t really work right if you fail to explicitly set a sort order on the list. I wasn’t really concerned with sort order, so I didn’t bother setting one at first. Once I set a sort order, everything worked fine.
If you want to see this quirk for yourself, run the test job below with and without the sortOrder() call. As far as I can tell, this isn’t actually documented anywhere, so I thought I’d write up this blog post, as a reminder for myself, and as a resource for anyone else who happens to stumble across this little quirk.
// https://gist.github.com/andyhuey/84495f8a3480d2df31f9
static void AjhTestRSL(Args _args)
{
CustTable custTable;
RecordSortedList myList = new RecordSortedList(tableNum(CustTable));
boolean moreRecs;
myList.sortOrder(fieldNum(CustTable, AccountNum));
// create a list
while select firstOnly10 * from custTable
{
myList.ins(custTable);
}
// step through the list
moreRecs = myList.first(custTable);
while (moreRecs)
{
info(custTable.AccountNum);
moreRecs = myList.next(custTable);
}
}
