FileMaker Custom Function:GetNthRecordSet ( fieldName ; recordNumStart ; recordNumEnd )

Calculates a return delimited and sorted, values list from related, or local, field data.

Description:

Creates a return delimited value list of the values from the field specified, beginning with the recordNumStart and ending with recordNumEnd. The resultant value list's scope and sort are determined by the source field; thus for local fields the sort is determined by the current sort of records in the found set, for related fields it is by the relationship sort.

This single Custom Function can replace Copy All primary keys of a foundset practice as well as the use of ValueListItems() to create a value list of related values for other relationships.

Parameters:

fieldName - Any local field, related field, or an expression that returns a field. NOTE: For repeating fields this Custom function will only see the first repetition, per record. Also, Globals will behave similarly and the global will be display once for each record.

recordNumStart - The record number from which you want to begin getting data. A null ("") or 0 value will set the start at the first record.

recordNumEnd - The record number after which you want to stop getting data. A null ("") or 0 value will evaluate until the the last record is reached. This parameter is inclusive, thus 10 will end the value list with the 10th record, including the contents of the field in that record.

Output Format:

A return delimited text value list of the the contents of fieldName dictated by the provided start and end record numbers.
Note: The result of GetNthRecordSet() will not be updated when the record referred to by GetNthRecordSet() is a record other than the one in which the calculation is currently being evaluated.

Examples:

Given the following related Field data for Children::FirstNames:
Related Record 1 = Jimmy
Related Record 2 = Suzzie
Related Record 3 = Johnny
Related Record 4 = Dweezle

GetNthRecordSet ( Children::FirstNames ; 1 ; 3 ) = Jimmy¶Suzzie¶Johnny

GetNthRecordSet ( ParentFirstName ; "" ; "" ) = Value list of all parent names in current found set, in sort order

GetNthRecordSet ( ParentFirstName ; 30 ; "" ) = Value list beginning with the 30th parent name till the last record in current found set, in sort order.

Special Thanks: To Ray Cologon, for refining the IsValid test instead of a cumbersome case test and his ubiquitously simplified code ideas!

Note: these functions are not guaranteed or supported by BrianDunning.com. Please contact the individual developer with any questions or problems.

Discuss:

Thank you SO much.

Eric Ruff, Gainesville
July 04, 2010 6:53pm

Has anyone tested the speed of this function versus going to a utility layout containing the key field and doing a copy of all the fields?

Thanks

Kevin Smith, London
April 13, 2011 3:03pm

I've seen some comparisons back in the day when the GetNthRecord function and recursion were new. But can't really recall how to locate them. This function is recursive so it has speed and recursion limitations with larger and larger record sets. The "copy all" method, which I used extensively prior to recursion, also has speed impact with larger record sets, as well as the downside of modifying the user's clipboard. You'll have to use your own judgement to pick the best method for the requirements you have.

In general, I limit my use of this to found sets <5000, but I also found my self doing the same with the "copy all" method for the same reasons. If you have to deal with sets bigger than that, I think it's better to re-architect the features around that to avoid the need to so this with either method (if possible).

Hope that helps a bit, please let us know if you find or do this kind of performance testing, it'd be good to log here for future reference!

Jonathan, Los Angeles
April 14, 2011 3:36pm

Hi
I have used this function with success on FM 10 Pro Adv on my PC. However on my Mac the recover function of FM reports an error saying "This formula has been changed". Happens when I recover same db - which I do occasionally to check my db.

Peter, Switzerland

Peter, Switzerland
July 30, 2011 7:02am

In my experience what you describe is a common occurrence with the "recover" command and custom functions... there are a large number of threads outlining the recover report saying this about a miscellaneous Custom Function or two in a file, even clean new files with new empty CF's! A Google search on this text will outline other people's similar experiences.

I'm pretty certain it's nothing to do with this specific calculation.

I've seen this in my own files with random Custom Functions too, what I usually do is remove the calc text in the CF, (though not delete the CF entry/name, so it doesn't break links) and replace it with "" and save my file out, compress/re-write the file as a copy or clone and then try the recover to see if it's actually still reporting this. Then I paste the function back in.

This doesn't usually DO anything, but it makes me feel better when the recover command erroneously says "this formula has been changed"... Someday, FileMaker will explain this or fix this behavior so we "Recover" can focus on actual problems in the files.

Best of luck!!!
Jonathan

Jonathan, Los Angeles
August 01, 2011 11:20am

Make a comment about this Custom Function (please try to keep it brief & to the point). Anyone can post:


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FileMaker Pro Custom Functions

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