Expression Syntax Reference

Logic block expressions define validation rules that evaluate against extracted document data. This page covers all supported syntax.

Field References

Reference extracted field values using the $ prefix followed by the field name:

$invoice_number
$total_amount
$vendor_name

Field names must exactly match the names defined in the Processor. Use snake_case naming.

For fields inside a group, use the same $field_name syntax — the expression context determines which group instance is being evaluated.

Literals

Text

Text values are written as plain tokens, without quotes:

$vendor_name = Acme Corp
$status != void

Multi-word text stays a single token. Quotes are only needed when the text would otherwise be read as an operator, number, or boolean — for example a literal dash is the token "-", and the literal text 100 is "100". Typing quotes in the expression editor marks the token as text and strips the quotes.

Numbers

Numeric literals (integer or decimal):

$total_amount > 0
abs($expected - $actual) < 0.01
$tax_rate = 8.25

Dates

Dates are represented internally as Unix timestamps in milliseconds:

$invoice_date > 1719806400000

The value 1719806400000 represents July 1, 2024. The expression builder provides a date picker that converts selected dates to timestamps automatically, and the date() function parses readable date text:

$invoice_date >= date(2024-07-01)

Operators

Arithmetic

Operator	Description	Example
`+`	Addition	`$subtotal + $tax`
`-`	Subtraction	`$expected - $actual`
`*`	Multiplication	`$unit_price * $quantity`
`/`	Division	`$total / $count`
`^`	Exponentiation	`$base ^ 2`

Comparison

Operator	Description	Example
`=`	Equal to	`$status = approved`
`!=`	Not equal to	`$vendor_name != ""`
`>`	Greater than	`$total_amount > 0`
`<`	Less than	`$discount < 100`
`>=`	Greater than or equal	`$quantity >= 1`
`<=`	Less than or equal	`$tax_rate <= 10`

Numeric = comparisons tolerate rounding differences smaller than a cent.

Logical

Operator	Description	Example
`and`	Both conditions must be true	`$total > 0 and $status = approved`
`or`	At least one condition must be true	`$status = approved or $status = pending`
`not`	Negates the following condition	`not $is_void`

Grouping

Use parentheses to control evaluation order:

($subtotal + $tax) = $total_amount
($status = approved or $status = pending) and $total > 0

Functions

Functions are grouped the same way as the picker in the expression editor.

Numbers

Function	Description
`sqrt(x)`	Square root
`abs(x)`	Absolute value
`round(x, decimals?)`	Round to the nearest whole number, or to the given number of decimal places
`roundDown(x)`	Round down to the nearest whole number
`roundUp(x)`	Round up to the nearest whole number
`max(a, b, ...)`	Largest of two or more numbers
`min(a, b, ...)`	Smallest of two or more numbers
`mod(a, b)`	Remainder after dividing `a` by `b`

Text

Text comparisons are case-sensitive.

Function	Description
`contains(text, search)`	True when `text` contains `search`
`startsWith(text, prefix)`	True when `text` begins with `prefix`
`endsWith(text, suffix)`	True when `text` ends with `suffix`
`length(text)`	Number of characters
`upper(text)`	Uppercase copy of the text
`lower(text)`	Lowercase copy of the text
`trim(text)`	The text without leading or trailing spaces
`concat(a, b, ...)`	Joins two or more values into one text
`matches(text, pattern)`	True when the text matches a regular expression; an invalid pattern is false
`fuzzyEquals(a, b, threshold?)`	Tolerant text comparison — forgiving of typos and case. Optional threshold 0–1, lower is stricter (default 0.4)

Dates

All date math uses UTC and truncates to the calendar day.

Function	Description
`today()`	Today’s date
`date(text)`	Parses date text (e.g. `2024-07-01` or `7/1/2024`) into a comparable date
`year(d)`	The year, e.g. 2024
`month(d)`	The month, 1–12
`day(d)`	The day of the month, 1–31
`weekday(d)`	The day of the week: 1 = Monday through 7 = Sunday
`addDays(d, n)`	The date `n` days after `d` (negative `n` goes backward)
`daysBetween(from, to)`	Whole days from one date to another

Fields & Values

Function	Description
`exists(field_name)`	True when the field was extracted with a non-empty value. Takes the bare field name, without the `$` — a `$field` reference would substitute the value first
`isEmpty(field_name)`	True when the field is missing or empty (bare field name, without `$`)
`isOneOf(value, option1, option2, ...)`	True when the value equals any of the listed options
`if(condition, true_value, false_value)`	Returns `true_value` when the condition holds, otherwise `false_value`
`lookup(value, Constant, lookup_column, return_column)`	Finds `value` in a column of a Constant and returns the matching value from another column. Falls back to fuzzy matching when there is no exact match

Line Items

These aggregate across all rows of a repeating field group within a single document. They take the bare field name, without the $.

Function	Description
`sumItems(field)`	Total of the field across all rows
`avgItems(field)`	Average of the field across all rows
`countItems(field)`	Number of rows
`minItems(field)`	Smallest value across all rows
`maxItems(field)`	Largest value across all rows
`sumItemsIf(field, { condition })`	Total of the field over only the rows matching the condition
`countItemsIf(field, { condition })`	Number of rows matching the condition

Inside the { } condition, reference the row’s fields with a double prefix — $$row_field — while single $field still refers to the document. For example, summing only labor line totals:

sumItemsIf(line_total, { $$item_type = labor }) = $labor_total

A logic block can reference fields from at most one repeating group.

Across Documents

These reach beyond the document being evaluated — into other documents of a processor or external data. They depend on document history: associated needs an id field and repeat uploads; lookback and lookahead need a primary date field.

Function	Description
`sumAll(field_name, processor)`	Total of a field across all documents of a processor, counting each `id` once (most recent upload wins)
`avgAll(field_name, processor)`	Average of a field across all documents of a processor
`lookback(field_name, processor, { condition })`	Scans documents backward from this document’s primary date and returns the field value from the most recent document matching the condition; false when nothing matches
`lookahead(field_name, processor, { condition })`	The same, scanning forward
`associated($id, field_name, processor)`	The field’s value from the most recent earlier upload sharing this document’s `id`; false when none exists
`cpi(start_date, end_date)`	US CPI inflation ratio between two dates — multiply a base amount by it to inflation-adjust

Inside a lookback/lookahead { } condition, $$field reads the candidate document being scanned, while single $field is this document’s value. For example, the amount from the last approved document:

lookback(amount, invoices, { $$status = approved }) > 0

Examples

Basic field check

$total_amount > 0

Ensures the total amount is positive.

Non-empty field validation

exists(vendor_name) and exists(invoice_number)

Ensures both vendor name and invoice number were extracted with values.

Tolerance check

abs($expected - $actual) < 0.01

Checks that two values are within a penny of each other.

Allowed values

isOneOf($status, approved, pending)

Checks the status against a list of acceptable values.

Format validation

matches($reference_code, ^REF-\d{4}$)

Checks that the reference code matches the expected pattern.

Line item reconciliation

sumItems(line_item_amount) = $total_amount

Verifies that the sum of all line item amounts equals the document total.

Due date validation

addDays($invoice_date, 30) = $due_date

Checks that the due date is exactly 30 days after the invoice date.

Weekday check

weekday($delivery_date) <= 5

Ensures the delivery date falls on a weekday.

Compound business rule

($subtotal + $tax) = $total_amount and $total_amount > 0

Validates that subtotal plus tax equals the total, and the total is positive.

Lookup against a constant

lookup($procedure_code, rate_schedule, procedure, rate) >= $billed_amount

Looks up the expected rate for a procedure code from the “rate_schedule” constant and checks that the billed amount does not exceed it.

Invoice recency check

daysBetween($invoice_date, today()) <= 365

Checks that the invoice date is within the last year.

Conditional tax calculation

if($is_taxable, $subtotal * 1.1, $subtotal) = $total_amount

Applies a 10% tax if the item is taxable, then checks the result matches the total.

Rate change against document history

associated($id, rate, carrier_invoices) = $rate

Checks that this document’s rate matches the rate from the previous upload with the same id.