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Builds a lookup table from a list: one entry per item, keyed by a value you pick out of it. Pair it with Flow Map Get to replace a Flow Lookup that runs inside a loop. Lookup rescans the whole list for every item; this indexes the list once and each read is direct.

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Configuration

  • Source — the list to index (usually an Assign).
  • Key source — how to compute each item’s key. Resolved against a single binding named item holding the current element, so use Extract with key item and a path, or Dated property with key item for fields like employee_no.
  • Value source — optional; what to store under the key. Leave blank to store the whole item. Set it to store just the piece you need, e.g. index employee mappings by external_id but store only employee_id.
  • Output assign — where the map is written.
  • On duplicate key — Last wins (default), Keep first, Collect all (the value becomes a list), or Halt flow. Reach for Halt flow when the key is supposed to be unique: it turns a silent wrong answer into an error naming the key.
  • On nil key — Drop (default), Store under nil, or Halt flow.

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Tips

  • Indexing a list that mixes two system integrations’ rows will collide on almost every key. Filter to one integration first, or use Collect all.
  • Items lost to a duplicate or a nil key are counted on a warning line. Drop this node’s log level to Warning to see what the index left out.
  • Keys are stored as text, so an integer key and its string form are the same entry — which is usually what you want when one side came from JSON.
  • The map is often large. Keep it off the Settings pane’s persist-assigns list, or every run row carries a copy of it.

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Ports