Expressions

SuperPlane uses Expr for expressions. Expressions let you reference data from upstream nodes, transform values, and control workflow logic.

Don’t want to write expressions by hand?

• Ask the agent: You can ask the built-in AI agent to write expressions for you. Just describe what you want to extract or calculate in the chat.
• Use the Preview tool: When typing {{ in a text field or $ in a condition field, the Canvas editing UI provides an autocomplete dropdown based on actual payload data from previous runs. You can also use the Preview tab in the node configuration to test your expressions against real data before running the workflow.

The message chain ($)

As a run executes, each node’s output is added to the message chain. Access it through $, referencing nodes by display name:

{{$['Node Name'].data.field}}
{{$['Node Name'].data.nested.field}}
{{$['Node Name'].data.array[0].value}}

Every entry also includes a .config property — the node’s resolved configuration at run time:

{{$['HTTP Request'].config.url}}
{{$['HTTP Request'].config.method}}

root() and previous()

Function	Returns
root()	The payload that started the run (the trigger event).
previous()	The immediate upstream node’s payload.
previous(n)	Walk n levels upstream.

{{root().data.ref}}
{{previous().data.status}}

previous() is not available when a node has multiple inputs (e.g. after a Merge). Use $['Node Name'] instead.

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Syntax: text fields vs conditions

Expressions appear in two contexts with slightly different syntax:

Text fields (URLs, message bodies, labels) — wrap each expression in {{ }}:

Deployment of {{$['Release'].data.name}} failed. See: {{$['Deploy'].data.workflow_run.html_url}}

Condition fields (If, Filter) — the entire field is one bare expression that must return true or false:

$['Get cat fact'].data.body.length <= 160 && $['Health Check'].data.body.healthy

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Operators

Beyond standard arithmetic (+, -, *, /, %, **) and comparison (==, !=, <, >, <=, >=):

Operator	What it does	Example
&& || !	Logical (aliases: and, or, not)	{{$['a'].data.ok && !$['b'].data.failed}}
contains	String contains substring	{{$['node'].data.body contains "error"}}
startsWith	String prefix check	{{$['node'].data.ref startsWith "refs/heads/"}}
endsWith	String suffix check	{{$['node'].data.branch endsWith "-hotfix"}}
matches	Regex match (RE2)	{{$['node'].data.msg matches "^fix\\(.*\\)"}}
in / not in	Membership test	{{$['node'].data.env in ["staging", "prod"]}}
??	Nil coalescing (fallback)	{{$['node'].data.label ?? "default"}}
? :	Ternary	{{$['node'].data.ok ? "pass" : "fail"}}
?.	Optional chaining	{{$['node'].data?.user?.name}}

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Closures (#)

Array functions accept a closure where # is the current element:

{{filter($['node'].data.items, # > 10)}}
{{map($['node'].data.users, #.name)}}
{{any($['node'].data.tags, # == "critical")}}
{{sortBy($['node'].data.alerts, #.severity, "desc")}}

reduce() adds #acc for the accumulator:

{{reduce($['node'].data.items, #acc + #.price, 0)}}

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Common patterns

Fallback for missing fields:

{{$['Webhook'].data.user.name ?? "unknown"}}

Ternary in a text field:

Status: {{$['Deploy'].data.success ? "Deployed" : "Failed"}}

Check array membership:

{{"production" in $['node'].data.environments}}

Filter and join:

{{join(filter($['node'].data.tags, # startsWith "env:"), ", ")}}

Date comparison (event in the last hour):

{{now().Sub(date($['node'].data.timestamp)).Hours() < 1}}

Build a JSON string:

{{toJSON({status: $['Deploy'].data.result, ref: root().data.ref})}}

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Function reference

SuperPlane expressions have access to the full set of Expr built-in functions for strings, arrays, dates, math, and type conversion. See the Expression Functions Reference for the complete list with signatures and examples.

For the Expr language specification, see the Expr documentation.