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Use variables in a flow

This page covers giving a flow values that change from run to run — a file URL, a dataset name, an API key. For what variables are and why, see Variables; for their properties and where a run's values come from, the Flows reference.

Define a variable

  1. In the flow builder, open the Variables tab of the Flow elements panel.
  2. Click New variable.
  3. Enter a Name — for example dataset. Names starting with system_ are reserved.
  4. Optionally add a Description, shown to whoever runs the flow.
  5. Leave Required on if a run cannot do without a value.
  6. To limit the values a run may give it, click Add option under Allowed options for each one. The run dialog then offers a list instead of a text field.
  7. Click Save, then Save the flow.

The system variables, such as system_triggererAccountName and system_triplyToken, are listed under System variables; they need no defining. A run started by a hook also gets variables describing the upload; see System variables.

Use a variable in a task

  • For a whole field: click $ beside the field and pick the variable, or Create a new variable to define one on the spot. This works for the fields in a task's settings and for the account, dataset and graph names of its inputs and outputs.
  • Inside text: in an email subject or body, a request's headers or body, or a Stop run message, write $dataset wherever the value should go: Imported $dataset.
  • In an inline SPARQL query: use a query variable with the same name. In select * { ?s ?p ?dataset }, ?dataset is replaced by the flow variable's value, as a string literal.
  • In a saved query: give its API variables a value under Query variables, choosing the flow variable.

Set a variable from a query

  1. Add a Set variables task (under Data processing) and connect it before the tasks that need the value.
  2. To query a dataset, connect it as the task's input.
  3. Under Query, write a SELECT query that selects the variables to set: select ?latest { … } order by desc(?date). Only its first row is used.
  4. Use $latest in the later tasks like any variable. The Variables tab lists it under Task output variables.

See Set variables for how the values are converted and when a flow cannot run.

Store a credential as a masked value

  1. Open Masked values in the flow's navigation and click Add masked value.
  2. Enter a Name — API_KEY, say — an optional Description, and the Value.
  3. Click Save.
  4. Use it in a task as $API_KEY, like any variable. In an Import from web or Send request task, for example, add a header Authorization with the value Bearer $API_KEY under Request headers.

Only people with the Manage flow masked variables permission see and change the value; everyone who may run the flow can use it.

Save a set of values as a preset

A flow needs at least one variable first.

  1. Open Presets in the flow's navigation and click Add Preset.
  2. Give it a label, fill in the Variables, and click Save.
  3. To have its values filled in whenever someone runs the flow or adds a schedule, switch on Default preset.

To run a flow with a preset, see Run a flow.