Work with variables
Pass values between steps, select the right output, and avoid empty or broken references.
What a variable contains #
A variable is a value supplied by a trigger, a workflow Property, or a node. It may contain a reply, an identifier, text from an AI response, a JSON result, or a database field.
Use the variable picker in a field that supports expressions. It inserts the reference in the form the application expects. Literal text and variables can appear together in the same text expression.
Give sources clear names #
Workflow Properties are reusable text settings you select through the same picker. Custom Node Types expose Properties as inputs supplied by each instance. Use these for configurable business information; use node outputs for values specific to the current run.
Name a lookup step orderLookup and a question step customerQuestion, for example. This makes the picker easier to read. Choose stable names before wiring many later steps to them.
After changing a source name or node type, inspect dependent fields and validation errors. A different node can expose different outputs even if it occupies the same spot on the canvas.
Read data in order #
Use a value only after the step that produces it has run. A value produced on another branch may not exist on the path currently executing.
For example, when a lookup has a not-found outcome, do not send a message that assumes an order number and delivery date were returned. Add a fallback response.
Common empty-value causes #
- The source step has not run yet.
- The customer has not answered a Receive Message step.
- Execution took a different branch.
- The source node is paused.
- The workflow Property has no value.
- A response extractor did not find the requested value.
- A copied workflow still refers to a source that needs remapping.
Use Set Variable #
Set Variable gives a value a named step in your workflow. Configure its Value field with text or an expression, then use its output in a later step. It is useful for a calculated or composed value, such as a short greeting.
The manual starter includes a working Set Variable example that you can import.
JSON is data, not a sentence #
Some outputs contain structured data encoded as text. Parse or extract the fields you need before presenting them to a person. When sending JSON to another service, ensure the final text remains valid JSON after variable substitution.
Use the relevant parser or response-extraction controls rather than relying on the visual appearance of a JSON string.