@UVALIDATE

@UVALIDATE is a REDCap action tag that validates a field against a check character (ISO/IEC 7064, Damm, Verhoeff, Luhn) or a regex format pattern, live as the value is typed.

@UVALIDATE is the module's flagship rule. It recomputes a field's check character, tests its format against a regex pattern, or both — and reports the two kinds of failure separately, so the person entering data knows which mistake they made.

Syntax

The tag has three forms, from shortest to most explicit. All three go in a field's Field Annotation box in the Online Designer.

@UVALIDATE                                        bare — all defaults (ISO 7064 Mod 37,36)
@UVALIDATE=verhoeff                               short — pick the algorithm
@UVALIDATE={"algorithm":"verhoeff","blockSave":"hard"}    JSON — every option

Algorithm shorthands

@UVALIDATE=verhoeff
@UVALIDATE=9710                 ISO 7064 Mod 97,10
@UVALIDATE=3736                 ISO 7064 Mod 37,36 (the default)
@UVALIDATE=gs1                  GS1 / GTIN / EAN / UPC barcodes
@UVALIDATE=isbn                 ISBN-10 weighted Mod-11

Format patterns instead of a check character

Set algorithm to none (or regex) and give a pattern. In stock REDCap a custom regex validation type has to be added server-wide by an administrator; here a project designer sets it per rule.

@UVALIDATE={"algorithm":"none","pattern":"FC[0-9]{4}"}
@UVALIDATE={"algorithm":"regex","pattern":"TB-[0-9]{6}","blockSave":"hard"}

Both at once

@UVALIDATE={"algorithm":"iso7064_mod37_36","pattern":"TB[A-Z]{3}-[0-9]{5}[0-9A-Z]"}
@UVALIDATE={"algorithm":"mod11_10","source":"digits_only"}
@UVALIDATE={"algorithm":"3736","strip":"-/ _|\\"}

Pooled fields

One box holding several IDs — space-separated, comma-separated, or run together with no separator — is split at the boundaries where the check character verifies, then shown as one chip per member.

@UVALIDATE={"type":"pooled","idLengths":[9],"expectedIds":3}
@UVALIDATE={"type":"pooled","algorithm":"none","pattern":"FC[0-9]{4}","idLengths":[6]}
@UVALIDATE={"type":"pooled","idMinLen":9,"idMaxLen":12,"blockSave":"confirm"}

Methods supported

Family	Members	Notes
ISO/IEC 7064	Mod 37,36 (default), Mod 11,10, Mod 97,10, Mod 11,2, Mod 37,2, two letters-only variants	Alphanumeric payloads
Classic decimal	Damm, Verhoeff, Luhn	Digit payloads, one check digit
Weighted modulus	GS1 Mod-10, ABA Mod-10, ICAO MRZ Mod-10, ISBN-10 weighted Mod-11	`weighted_mod11` may emit `X`
None	`none` / `regex`	Format pattern only

The three Mod-10 schemes catch every single-digit error at any length but miss adjacent swaps of digits differing by 5. weighted_mod11 catches every single-digit error and every adjacent swap only up to 9 digits — the ISBN-10 domain. At 10 or more digits the position carrying weight 11 goes blind to substitutions, so prefer Mod 11,2 or Mod 97,10 for longer numbers.

The method must match how the IDs were minted. A check character is only meaningful against the scheme that produced it — pointing @UVALIDATE at the wrong algorithm will reject valid IDs.

Conditional validation with `when`

Any rule may carry a condition and validate only while that condition is true.

@UVALIDATE={"algorithm":"verhoeff","when":"[specimen_type]='2'"}
@UVALIDATE={"algorithm":"none","pattern":"FC[0-9]{4}","when":"[consent(1)]='1' and [site]<>'9'"}

The condition language is a REDCap-style subset, not byte-for-byte REDCap logic:

Supported	Rejected when the rule is saved
`[field]` and `[checkbox(code)]` references	Functions such as `datediff(...)`
`'text'`, `"text"` and number literals	Smart variables such as `[record-name]`
`=` `<>` `!=` `>` `<` `>=` `<=`	`[event][field]` cross-event prefixes
`and` / `or` / `not`, parentheses	Arithmetic and piping

Branched validation

Several @UVALIDATE tags with different when conditions on one field branch, plus at most one tag without a condition as the fallback.

@UVALIDATE={"algorithm":"verhoeff","when":"[specimen_type]='2'"}
@UVALIDATE={"algorithm":"none","pattern":"FC[0-9]{4}"}          ← the "otherwise"

The "should end in X" hint

A hint naming the expected check character is available per rule via suggestFix, but it is off by default. A visible expected character can entice staff to force-fit a mistyped ID instead of re-scanning it.

@UVALIDATE={"algorithm":"3736","suggestFix":true,"note":"Blood specimen barcode"}

Field types

Check-character and regex validation apply to Text and Notes fields. The other rule kinds cover a wider set — see each tag's page.