$var.{name} — Workflow Variables

How $var Variables Are Set

Workflow variables are populated by the SetVariable built-in node. The designer configures a variable name and a value expression. When the SetVariable node runs, it calls ctx.ExecutionMemory.SetGlobal(name, value) internally.

// SetVariable node configuration (in the node's config panel)
{
  "variableName": "selectedRegion",
  "valueExpression": "$json.body.region ?? 'us-east-1'"
}

// After this node runs, $var.selectedRegion resolves to the computed value
// Any downstream node can use:
$var.selectedRegion

Expression Examples

// Read a simple string variable
$var.selectedRegion

// Read a variable and use it in a URL template
"https://api.{{$var.selectedRegion}}.example.com/orders"

// Use in a condition
$var.retryCount < 3

// Use in arithmetic
$var.basePrice * 1.2

// Nested object variable
$var.userProfile.role == "admin"

Updating Variables — Multiple SetVariable Nodes

A $var variable can be updated during the execution by placing additional SetVariable nodes further in the graph. Each SetVariable call overwrites the previous value. This enables patterns like counters and accumulators within a single run.

// Pattern: counter incremented by a SetVariable node in a loop
// SetVariable node config — reads current value and increments
{
  "variableName": "itemCount",
  "valueExpression": "($var.itemCount ?? 0) + 1"
}

// Each time this SetVariable node runs, $var.itemCount increases by 1

$var vs. SetGlobal in Executors

Lifetime

$var variables are ephemeral — they exist only for the current execution run. They are NOT accessible in future runs. If cross-run persistence is needed, use pinned data.