Enabling loop on a step

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Enabling Loop

To enable looping for a step:
  1. Click the step’s options menu (⋮)
  2. Click Add Loop
  3. Enter a loop expression that determines how the step iterates

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Loop Expression

  • A JavaScript expression that returns the next item to process
  • Returns null, undefined, or false to terminate the loop
  • Has access to special variables:
    • index: Current iteration number (starts at 0)
    • item: Current value being processed

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Loop Output

  • When loop is enabled, the step’s output becomes an array
  • Each array element contains the output from one iteration
  • Output array maintains the order of processing

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Loop Expression Rules

  • Return one item at a time from the array: return items[index];
  • Never return the full array (causes infinite loop)

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Accessing Output

When a step has looping enabled, its output becomes an array containing results from each iteration: 
const results = modelStep.output.map((item) => item.message);
When accessing the output of a looped step in code steps, you must use array methods like map() to access individual iteration results.

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Loop Termination

Loop stops when the expression returns null, undefined, or false. Array bounds automatically handle termination: 
return items[index]; // Returns undefined when index >= length

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Examples

Here are some practical examples demonstrating how to use loops in your workflows:

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Parallel API Requests

Process multiple API endpoints simultaneously: Parallel API Requests

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File Batch Processing

Process multiple files with consistent logic: Files Batch Processing This eliminates the need for separate model steps for each file.

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Remove Loop

To remove a loop from a step:
  1. Click the step’s options menu (⋮)
  2. Click Remove Loop