FileMakerHacks

Demo file: virtual-list-even-more-simplified.zip  [expects, but does not require, FM 22 or later]

Note 1: The example in today’s article/demo is intentionally very basic.
Note 2: The demo is self-populating to keep the data current, so the values you see in the screen shots may not exactly match those you encounter in the demo.

As long time readers may recall, between 2011 and 2019 this blog featured numerous articles touching on various aspects of the virtual list technique — or, more properly, series of techniques. The following year, in 2020, I decided to distill the core bits into a basic “beginner’s guide” with accompanying demo file, and I called it Virtual List Simplified. And if you’re still using FM 21 or earlier, and are looking for an introduction to virtual list, I highly recommend that article.

However, with the release a few months ago of FM 22 (a.k.a. FileMaker 2025), the landscape dramatically changed thanks to a re-written JSON engine that is significantly more powerful (i.e., faster) than before. Why should that matter? Because JSON is typically where virtual list gets its data from, and thanks to this awesome performance boost, it’s time to recycle and update the 2020 article and accompanying demo file to take advantage of it. And good news: it’s now less complicated and easier to understand.

At the risk of stating the obvious, there are many, many ways to skin the virtual list cat, and the purpose of today’s article is not to say “this is the best way”, or imply that other approaches are flawed, but simply to propose one particular approach you might take — especially if you are either: a) new to virtual list, or b) already using virtual list, but aren’t completely happy with your current implementation.

At any rate, my aim today is to gather useful insights from earlier articles into a single document (with a couple new ideas thrown in), and some of what follows has been recycled from those earlier articles.

Spoiler alert: two-dimensional JSON arrays are now viable and performant as back-ends for virtual list. Prior to FM 22 this was not the case… things would appear to be fine when the 2D array was relatively small, but would slow down dramatically with larger 2D arrays. For details see Virtual List with a 2D JSON Array in “FileMaker Pro 22: Initial Impressions”.

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