Writing expressions

Expression nodes transform data using the ZEN expression language. Use them to calculate values, reshape data, and prepare outputs.

Creating an expression node

Drag an Expression node onto the canvas
Connect it to your data flow
Click Edit Expression to open the editor
Define output fields and their expressions

Expression structure

Each expression node produces an output object. You define fields and the expressions that calculate them:

Accessing data

Reference input data using dot notation:

customer.name           // Nested object access
order.items[0].price    // Array indexing

Referencing previous nodes

Use $nodes to access output from any upstream node by its name:

$nodes.CreditCheck.rating       // Output from "CreditCheck" node
$nodes.RiskScore.value          // Output from "RiskScore" node
$nodes["My Node"].field         // Use brackets for names with spaces

See Useful patterns for more examples.

Operators

Arithmetic

price * quantity        // Multiplication
total / count           // Division
base + bonus            // Addition
gross - deductions      // Subtraction
amount % 100            // Modulo (remainder)
2 ^ 10                  // Power (1024)

Comparison

age >= 18               // Greater than or equal
status == "active"      // Equal
tier != "basic"         // Not equal
score < threshold       // Less than

Logical

isActive and hasPermission    // Both must be true
isAdmin or isOwner            // Either can be true
not isBlocked                 // Negation

Ternary (conditional)

score > 70 ? "pass" : "fail"
age >= 18 ? "adult" : age >= 13 ? "teen" : "child"

Null handling

user.nickname ?? user.name ?? "Anonymous"    // First non-null value

Range checks

age in [18..65]         // Inclusive range
score in (0..100)       // Exclusive range
value not in [1..10]    // Outside range

Built-in functions

Math

Function	Example	Result
`abs(n)`	`abs(-5)`	`5`
`round(n)`	`round(3.7)`	`4`
`floor(n)`	`floor(3.9)`	`3`
`ceil(n)`	`ceil(3.1)`	`4`
`min(arr)`	`min([3, 1, 4])`	`1`
`max(arr)`	`max([3, 1, 4])`	`4`
`sum(arr)`	`sum([1, 2, 3])`	`6`
`avg(arr)`	`avg([10, 20, 30])`	`20`

String

Function	Example	Result
`len(s)`	`len("hello")`	`5`
`upper(s)`	`upper("hello")`	`"HELLO"`
`lower(s)`	`lower("HELLO")`	`"hello"`
`trim(s)`	`trim(" hi ")`	`"hi"`
`contains(s, sub)`	`contains("hello", "ell")`	`true`
`startsWith(s, prefix)`	`startsWith("hello", "he")`	`true`
`split(s, delim)`	`split("a,b,c", ",")`	`["a","b","c"]`

Array

Function	Example	Result
`len(arr)`	`len([1, 2, 3])`	`3`
`map(arr, expr)`	`map([1, 2, 3], # * 2)`	`[2, 4, 6]`
`filter(arr, expr)`	`filter([1, 2, 3, 4], # > 2)`	`[3, 4]`
`some(arr, expr)`	`some([1, 2, 3], # > 2)`	`true`
`all(arr, expr)`	`all([1, 2, 3], # > 0)`	`true`
`flatMap(arr, expr)`	`flatMap([[1,2], [3]], #)`	`[1,2,3]`

The # symbol represents each element when iterating over arrays.

Date

Function	Example	Result
`d(str)`	`d("2024-01-15")`	Date object
`d().year()`	`d("2024-01-15").year()`	`2024`
`d().month()`	`d("2024-01-15").month()`	`1`
`d().day()`	`d("2024-01-15").day()`	`15`
`d().add(n, unit)`	`d("2024-01-15").add(7, "d")`	7 days later
`d().diff(d2, unit)`	`d("2024-01-15").diff("2024-01-01", "day")`	`14`

Getting Started

Authoring

ZEN Language

Tutorials

Creating an expression node

Expression structure

Accessing data

Referencing previous nodes

Operators

Arithmetic

Comparison

Logical

Ternary (conditional)

Null handling

Range checks

Built-in functions

Math

String

Array

Date

Common patterns

Calculate totals

Categorize values

Work with dates

​Creating an expression node

​Expression structure

​Accessing data

​Referencing previous nodes

​Operators

​Arithmetic

​Comparison

​Logical

​Ternary (conditional)

​Null handling

​Range checks

​Built-in functions

​Math

​String

​Array

​Date

​Common patterns

​Calculate totals

​Categorize values

​Work with dates

Creating an expression node

Expression structure

Accessing data

Referencing previous nodes

Operators

Arithmetic

Comparison

Logical

Ternary (conditional)

Null handling

Range checks

Built-in functions

Math

String

Array

Date

Common patterns

Calculate totals

Categorize values

Work with dates