Conditions

Gate a mapped field on skip-if-empty, a value comparison, or a hand-written Liquid expression — so a field only appears in the output when it genuinely applies.

Not every mapped field should always appear in the output. A middle name only exists for some patients. A bed location only makes sense for an inpatient encounter. Conditions let a field mapping declare when it applies — so instead of the field always showing up (sometimes with a blank or misleading value), it's simply left out of the output entirely when the condition doesn't hold.

What it looks like end to end

Here, an admission message wires five fields — two of them conditionally. Middle Name only emits a value when the patient actually has one on file. Location only emits a value when the visit's patient class is I (inpatient) — an outpatient visit has no bed to report.

The mapping editor with five target fields wired from an HL7 admission message, two of them carrying a condition, and a Live Output panel showing all five populated — Both conditions hold for this message — `Middle Name` and `Location` both appear in Live Output, right alongside the three unconditional fields.

How you know a field is conditional

Every mapped row carries a small condition icon next to its checkmark. Idle, it's a plain outline — click it to add a condition. Once a condition is set, the same icon turns blue, so a glance down the tree tells you which fields are unconditional and which aren't.

1 — Class has no condition: the icon sits idle, a plain outline. 2 — Middle Name has one: the same icon turns blue. Clicking it either way opens the same modal.

Three ways to gate a field

Clicking the condition icon opens one modal with a per-term mode picker. Every condition starts here, whichever of the three you need:

Conditions modal set to Skip if empty mode, testing the field's own source reference PID.5.3 — **Skip if empty** — the default, and the one you'll reach for most. 1 picks the mode. 2 is the field reference being tested — here it's the mapped field's own source (`PID.5.3`), pre-filled automatically, but it can point at any field: skip a whole address block unless a "has address" flag is set, for instance.

Conditions modal set to Compare value mode, testing PV1.2 equals I — **Compare value** — reach for this when presence alone isn't enough and the field's actual value decides. 1 switches to this mode. 2 is the comparison itself: a field reference, an operator (equals, not-equals, contains, and the four numeric comparisons), and a literal to compare against — here, only include `Location` when `PV1.2` (Patient Class) equals `I`.

Conditions modal set to Raw Liquid condition mode, with a hand-written expression combining two comparisons with or — **Raw Liquid condition** — the escape hatch, for logic the picker doesn't have a field for. 1 switches to it. 2 is a hand-written Liquid expression, evaluated exactly as written — here, including a field for both inpatient and emergency visits: `PV1.2 == 'I' or PV1.2 == 'E'`. A raw expression replaces the picker entirely for that term rather than combining with it.

When to reach for each

Skip if empty covers the common case — a field that simply shouldn't appear when there's nothing to put in it. Compare value is for a specific value deciding inclusion, without writing any Liquid yourself. Raw Liquid is there for everything else — combining several fields with your own logic, once presence and simple comparisons aren't expressive enough. Whichever mode, the effect is the same: HL7 and X12 target positions render blank without shifting anything else out of place, and JSON keys are omitted entirely.