Препратка към стойности
The ${fieldname} syntax is used to refer to the current value of a different field in your form. It can represent the value that was entered, selected, or calculated, and it will be displayed exactly as it appears in the submitted data.
Example:
If you have a field named “age” and you want to retrieve the exact value that was entered in that field, you can use ${age}.
When it comes to constraints, the “.” symbol is used to refer to the user’s proposed entry or selection for the current field. It allows you to apply conditions or limits based on the value the user is entering or selecting at that moment.
Example:
If you want to check if the proposed value for the current field is less than 3, you can use the constraint . < 3.
.. — Parent group reference
Inside a group or repeat group, .. refers to the parent context. This is rarely needed in practice but is used in advanced XPath expressions to navigate the form hierarchy.
Where references are used
| Column | Reference type | Example |
|---|---|---|
relevant | ${fieldname} | ${consent} = 'yes' |
constraint | . for current field, ${fieldname} for others | . > 0 and . <= ${max_value} |
calculation | ${fieldname} | ${adults} + ${children} |
required | ${fieldname} | ${has_income} = 'yes' |
default | ${fieldname} | ${previous_answer} |
label | ${fieldname} in text | "Your age is ${age} years" |
choice_filter | Column name (no ${}) | district = ${district} |
In the choice_filter column, reference choice column names directly (without ${}), and reference form fields with ${}. Mixing these up is a common source of errors.
Referencing values inside repeat groups
Inside a repeat, ${fieldname} refers to the field in the same instance of the repeat:
relevant: ${member_age} < 18
This uses the member_age value for the current repeat instance, not all instances.
To reference a field in a specific repeat instance from outside the repeat, use indexed-repeat():
indexed-repeat(${member_name}, ${household_members}, 1)
See Functions — Repeated field functions for full details.
Empty value checks
Test whether a field has been answered:
${fieldname} != '' (field is not empty)
${fieldname} = '' (field is empty)
For numbers, also check:
${age} > 0 (age has a positive value — implicitly not empty for numeric context)
Type coercion in references
When you use ${fieldname} in a numeric context (e.g., ${age} + 1), rtSurvey automatically coerces the string value to a number. An empty field coerces to 0 or NaN depending on the operation — use coalesce(${field}, 0) to safely default an empty numeric field to zero.