Lookup

Left-join enrich: match a primary field to a lookup table column, then copy selected columns onto the row.

Parameters

lookupKey (Lookup table, string, required) — Key into lookups (edge lookupKey). Default: "".
matchField (Match data field, string, required) — Primary row field to match. Default: "".
matchColumn (To lookup field, string, required) — Lookup table field to match against. Default: "".
take (Take, array of objects (column, as), required) — Lookup fields to copy onto the primary row (optional destination rename). Default: [].

Field selection

Lookup does not use Operation source or target. Configure lookupKey, matchField, matchColumn, and take in the Lookup badge (or params).

JSON Configuration

{
  "id": "op-lookup",
  "type": "transformation",
  "action": "lookup",
  "params": {
    "lookupKey": "venues",
    "matchField": "venue",
    "matchColumn": "code",
    "take": [
      {
        "column": "name",
        "as": "venue"
      },
      {
        "column": "region",
        "as": "venue_region"
      }
    ]
  },
  "testInputs": [
    "Hello World",
    "MixedCase",
    "sample text",
    "already",
    "123",
    ""
  ]
}

Lookup table and match

The lookup table is not a field on the Operation. You wire a Static Data node (or another tabular source) into the Operation input with mergeStrategy: "lookup" and a lookupKey on the edge. That key becomes lookups[lookupKey] at run time.

params.lookupKey must match the edge lookupKey (or the title-slug default from a Static Data node). matchField is the primary-row field. matchColumn is the column on the lookup table. Match is strict === (no trim or coerce).

Take columns

take is an array of { column, as? } objects, not nested operations:

column: Field on the matched lookup row to copy.
as: Optional rename on the primary row. Omit it to keep the lookup column name.

A miss leaves the primary row unchanged and writes an info audit. Several matching lookup rows use the first row in table order (also info). Empty take, missing lookupKey / matchField / matchColumn, or a missing lookups[lookupKey] table fails the run.

Stack one Lookup op per match field or table. Prefer Lookup over a custom Function that reads lookups.

Explore Static Data Replacements and Multi-table Lookup Enrichment show stacked Lookup ops against one or more Static Data tables.