Variable Assignment — Configuration

Properties

Property	Type	Required	Default	Description
`variable_name`	string	Yes	—	The name under which the value is stored in workflow memory. Must be a valid identifier (letters, numbers, underscores; no spaces). Case-sensitive. Examples: `invoiceTotal`, `customerId`, `isApproved`.
`value`	string \| number \| boolean \| null	No	null	A literal value to assign directly. Can be a string (`"pending"`), number (`42`), or boolean (`true`). Set to `null` to remove the variable from memory entirely. Mutually exclusive with `value_expression` — if both are supplied, `value_expression` takes precedence.
`value_expression`	string (BizFirst expression)	No	—	A BizFirst expression evaluated at runtime to produce the value. Supports all expression prefixes: `{@ $input.current.amount }`, `{@ var.subtotal + var.tax }`, `{@ output.GetCustomer.data.name }`. When present, overrides any `value` literal.
`scope`	string enum	No	`execution`	Controls the lifetime and visibility of the variable. execution — The variable lives for the entire workflow run and is accessible from any node. local — The variable is scoped to the current execution block (e.g., inside a Loop or TryBlock) and is discarded when that block exits.

Expression Prefixes

The value_expression field supports the following context prefixes inside {@ ... }:

$input.current.* — The trigger / initial input data of the workflow
var.* — Access any previously assigned workflow variable by name
output.NodeName.* — Access the output of a specific named upstream node
input.* — Alternative reference to the raw workflow input object

Scope Behaviour

Understanding variable scope is critical for loops and parallel branches:

Scope	Accessible From	Lifetime	Use When
`execution`	Any node in the entire workflow	Entire workflow run	You need the value after the current block completes; default choice for most scenarios.
`local`	Only nodes within the same block (Loop body, TryBlock, etc.)	Until the enclosing block exits	Temporary loop scratch variables that should not pollute the top-level namespace.

Null Assignment Removes the Variable

Setting value to null (and providing no value_expression) will remove the named variable from memory completely. Downstream nodes that attempt to read a removed variable will receive null rather than an error, so design conditional logic accordingly.

Naming Conventions

Variable names must begin with a letter or underscore and may contain only alphanumeric characters and underscores. The runtime is case-sensitive: invoiceTotal and InvoiceTotal are two different variables. Recommended conventions:

Use camelCase for all variable names (e.g., customerName, orderSubtotal)
Prefix loop-iteration temporaries with _ (e.g., _loopItem) to signal local intent
Avoid very generic names like data or result in long workflows to prevent collisions

JSON Configuration Example

{
  "node_type": "VariableAssignment",
  "name": "StoreInvoiceTotal",
  "config": {
    "variable_name": "invoiceTotal",
    "value_expression": "{@ var.subtotal + var.taxAmount }",
    "scope": "execution"
  }
}

Configuration Reference

Properties

Scope Behaviour

Naming Conventions

JSON Configuration Example