Conditional Field Validator

This REDCap External Module allows you to create simple rule-based validations that run during data entry and survey completion.

How It Works

Each rule contains two parts:

1. Trigger

You specify:

• Trigger Field — the field to watch.
• Trigger Condition — a value or a regular expression.
  • The rule activates only when this condition is met.

2. Validation

Once the trigger condition is true, you define:

• Validation Field — the field to validate.
• Validation Condition — a value or a regular expression that the field must match.
• Error Message — the message shown to the user if validation fails.

If validation fails:

• The target field is highlighted.
• An information icon appears showing the error message on hover.
• Form buttons are disabled while errors exist.

Summary

1. Trigger Field + Condition → decides when to run validation.
2. Validation Field + Condition + Error Message → decides what to validate and what message to show.

Upload your rules file in the External Module project settings to activate the validations.