Expressions basics

Expressions are short formulas used across the builder: in logic properties (visibleIf, disableIf…), calculated values, validators, action conditions, and option filters.

Referencing fields

Wrap an element name in curly braces to get its current value:

{country}                    value of the element named "country"
{clientType} == "company"    comparison
{price} * {quantity}         math

If the referenced field is empty, the token resolves to an empty value — use isEmpty() / notEmpty() to test for that.

Operators

Kind	Operators
Comparison	== != > >= < <=
Logic	&& (and), || (or), ! (not)
Math	+ - * /
If/else in one line	condition ? valueIfTrue : valueIfFalse

Examples:

{age} >= 18 && {country} == "LT"
{isVip} ? {amount} * 0.9 : {amount}
!isEmpty({email}) || !isEmpty({phone})

Functions

40+ built-in functions cover text, arrays, numbers, and dates:

isEmpty({companyCode})
contains({roles}, "admin")
toNumber({price}) * toNumber({quantity})
dateDiffDays({startDate}, {endDate})

Full list with examples: Function reference.

Context tokens

Token	Available	Meaning
{fieldName}	everywhere	Value of a named element
row.fieldName / row.index	inside tables	Current row's field / index
panel.fieldName / panel.index	inside dynamic panels	Current entry's field / index
parentIndex	nested repeaters	Index in the surrounding repeater
{__variables.name}	everywhere	A variable (route param, constant, computed)
{__external.name}	everywhere	Context provided by the host application (user, role…)
{el1[parentIndex].country}	nested repeaters	Indexed access into a repeater's data

Runtime state of some containers is also addressable: {myTabs.selectedTab}, {flow.selectedStepIndex}.

Boolean vs. value expressions

• Condition properties (visibleIf, disableIf, requireIf, readonlyIf, resetIf, validator conditions, action conditions) must return true or false.
• Value properties (expression, defaultValue) may return text, a number, a boolean, an array, or an object.

When expressions run

An expression re-evaluates automatically whenever any field it references changes. For text inputs you can tune when with Logic execution mode: on input (every keystroke), on change, or on blur (leaving the field).

Debugging

Wrap any part in dbg(value, "label") — it logs the value to the browser console and passes it through unchanged:

visibleIf: dbg({clientType}, "clientType") == "company"

The expression editor also shows an inline help panel with tokens, functions, and example patterns for the property you are editing.