Designing calculation field libraries

Expert

Organize and document a reusable library of calculation fields and custom functions that can be cleanly transferred between FileMaker solutions.

What you'll learn

  • How to structure a custom function library with namespace prefixes
  • How to document custom functions so they survive transfer to new files
  • Which calculation patterns are best abstracted as custom functions vs. inline calcs
  • How to maintain a library version history

Every well-run FileMaker practice has a library of proven calculation patterns: custom functions, utility calculation fields, and scripted helpers that have been tested and refined over years. Designing that library for portability -- naming it consistently, avoiding hard field references, and documenting the design intent -- is what separates a collection of one-off solutions from a reusable toolkit.

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Namespace conventions for custom functions

Use dot-notation namespaces to group related functions. The namespace should describe the category, and the function name should describe the operation as a verb-noun pair.

FileMaker Script
// Namespace conventions:
Text.TrimMultipleSpaces ( text )
Text.StripHTML ( text )
Text.TitleCase ( text )

Date.FirstOfMonth ( date )
Date.LastOfMonth ( date )
Date.WorkingDaysBetween ( startDate ; endDate )

List.RemoveDuplicates ( list )
List.SortAscending ( list )
List.Contains ( list ; value )

JSON.GetNestedValue ( json ; path )
JSON.ArrayToList ( json ; keyName )

Number.FormatCurrency ( amount ; symbol )
Number.Clamp ( value ; minVal ; maxVal )
Calculation debugging techniquesCalculation code review checklist

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