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Tracecat will always support unlimited workflows. We recommend breaking up your workflows into smaller, reusable workflows whenever possible.

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What you’ll learn

By the end of this tutorial, you’ll learn how to:
  • Call a workflow from another workflow
  • Give a workflow a human-readable alias
  • Use trigger_input to pass data into a child workflow
  • Use Output Schema to define the data returned from a child workflow

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Execute child workflow

Use the core.workflow.execute action to call a workflow from another workflow. You can call a workflow by workflow_alias (recommended) or by workflow_id. Execute child workflow

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Alias

Give your workflows an alias to call them by a human-readable name, in core.workflow.execute, as opposed to the workflow ID. Configure workflow alias

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Trigger Inputs

In the workflow triggers tutorial, we learned how to pass data into workflows via webhook payloads. Passing data into child workflows works the same way.
To pass data into a child workflow, specify trigger_inputs in the core.workflow.execute action’s inputs. trigger_inputs takes a JSON-serializable object exactly like webhook payloads. For example, the core.workflow.execute action inputs might be configured as: 
workflow_alias: get_weather
trigger_inputs:
  latitude: 37.773972
  longitude: -122.431297

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Wait Strategy

The wait_strategy parameter controls how the core.workflow.execute action behaves after creating a child workflow:
  • detach (default): The action returns immediately after creating the child workflow, without waiting for it to complete. The parent workflow continues execution.
  • wait: The action waits for the child workflow to complete before marking itself as complete. Use this when you need the child workflow’s result.
For example, to explicitly wait for a child workflow to complete: 
workflow_alias: get_weather
trigger_inputs:
  latitude: 37.773972
  longitude: -122.431297
wait_strategy: wait
Use detach (default) when:
  • Running fire-and-forget tasks
  • Processing items in parallel without dependencies
  • You don’t need the child workflow’s result
Use wait when:
  • You need the child workflow’s output for subsequent actions
  • The child workflow must complete successfully before proceeding
  • You’re implementing sequential processing logic
In detach mode:
  • You cannot access the child workflow’s output in subsequent actions
  • A failing child workflow will not affect the parent workflow
  • The parent workflow may complete before the child workflow finishes

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Output Schema

We recommend users define an Output Schema for every workflow.
You can use all core expression contexts: e.g. ACTIONS, TRIGGER, FN within the Output Schema field.
By default, workflows return a JSON object that contains the entire workflow context. The workflow context includes the inputs and outputs of every action from the workflow run. You almost never want to return the entire workflow context as the output of a workflow. The Output Schema field under the Schemas tab in workflow settings allows you to define the data returned from a workflow. Output Schema The data returned from a workflow can be any JSON-serializable value. For example, the Output Schema field can be configured as a nested JSON object: 
temperature: ${{ ACTIONS.http_request.result.data.current.temperature_2m }}
coordinates:
  lat: ${{ TRIGGER.latitude }}
  long: ${{ TRIGGER.longitude }}
timestamp: ${{ ACTIONS.http_request.result.data.time }}
or even a single value: 
${{ ACTIONS.http_request.result.data.current.temperature_2m }}

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Tutorial

This tutorial assumes you’ve already completed the Quickstart tutorial.
In the quickstart tutorial, we built a workflow called Get weather that calls a weather API for the temperature. Let’s build another workflow that calls the Get weather workflow for three different locations (New York, London, and Tokyo).
1

Parameterize child workflow

We currently hardcode the coordinates in the Get weather workflow. Let’s change this so that we can pass in coordinates from the webhook trigger into the HTTP Request action.
url: https://api.open-meteo.com/v1/forecast
method: GET
params:
  latitude: ${{ TRIGGER.latitude }}  # Was 37.773972
  longitude: ${{ TRIGGER.longitude }}  # Was -122.431297
  current: temperature_2m
Latitude and longitude trigger inputs
2

Create parent workflow

Create a new workflow. Add three core.workflow.execute actions to the workflow, one for each location. Configure each core.workflow.execute action to call the Get weather workflow (with alias get_weather) with the appropriate coordinates.
We’re using wait_strategy: wait here because we want to see the temperature results in the parent workflow. If you don’t need the results and just want to trigger the child workflows, you can omit this parameter to use the default detach mode.
workflow_alias: get_weather
trigger_inputs:
  latitude: 40.7128
  longitude: 74.0060
wait_strategy: wait  # Wait for result
Parent workflow
3

Run parent workflow

Run the parent workflow. Notice in Action result that the child workflow returns the entire workflow context as the output of the parent workflow. In this next step, we’ll add an Output Schema to the Get weather child workflow to return only the temperature.
  • Events
  • Action input
  • Action result
View events
4

Add output schema

Add an Output Schema to the Get weather workflow. Configure the Output Schema to return only the temperature. Save the workflow.
${{ ACTIONS.http_request.result.data.current.temperature_2m }}
Return value
5

Rerun parent workflow

Run the parent workflow again. Notice in Action result that the child workflow now returns only the temperature.Rerun parent workflow