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Foreign keys let you link documents across indexes so that search results are automatically enriched with related data. Instead of duplicating information, you store it once in a dedicated index and reference it by ID. For example, a movies index can reference actors by ID. When you search for movies, Meilisearch automatically replaces the actor IDs with full actor documents from the actors index. This approach also works with multi-search when querying across related indexes.
Foreign keys is an experimental feature. Its API and behavior may change in future releases. It is not supported in remote sharding environments.

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Step 1: Enable the experimental feature

Foreign keys must be activated through the experimental features endpoint before you can use them: 
curl \
  -X PATCH 'MEILISEARCH_URL/experimental-features' \
  -H 'Content-Type: application/json' \
  --data-binary '{
    "foreignKeys": true
  }'
Add documents to the index you want to reference. In this example, create an actors index with actor data: 
curl \
  -X POST 'MEILISEARCH_URL/indexes/actors/documents' \
  -H 'Content-Type: application/json' \
  --data-binary '[
    { "id": 1, "name": "Tom Hanks", "born": 1956 },
    { "id": 2, "name": "Robin Wright", "born": 1966 },
    { "id": 3, "name": "Gary Sinise", "born": 1955 }
  ]'

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Step 3: Configure foreign keys in the main index

Use the settings endpoint to define which fields contain foreign references and which index they point to: 
curl \
  -X PATCH 'MEILISEARCH_URL/indexes/movies/settings' \
  -H 'Content-Type: application/json' \
  --data-binary '{
    "foreignKeys": [
      {
        "fieldName": "actors",
        "foreignIndexUid": "actors"
      }
    ]
  }'
This tells Meilisearch that the actors field in the movies index contains IDs that reference documents in the actors index.

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Step 4: Add documents with foreign IDs

Add documents to your main index. Use arrays of IDs for the foreign key field: 
curl \
  -X POST 'MEILISEARCH_URL/indexes/movies/documents' \
  -H 'Content-Type: application/json' \
  --data-binary '[
    { "id": 1, "title": "Forrest Gump", "actors": [1, 2, 3] },
    { "id": 2, "title": "Cast Away", "actors": [1] }
  ]'

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Step 5: Search and see hydrated results

When you search the movies index, Meilisearch automatically replaces foreign IDs with full documents from the referenced index: 
curl \
  -X POST 'MEILISEARCH_URL/indexes/movies/search' \
  -H 'Content-Type: application/json' \
  --data-binary '{ "q": "forrest" }'
Without foreign keys, a result would look like this: 
{
  "id": 1,
  "title": "Forrest Gump",
  "actors": [1, 2, 3]
}
With foreign keys configured, the same result is automatically hydrated: 
{
  "id": 1,
  "title": "Forrest Gump",
  "actors": [
    { "id": 1, "name": "Tom Hanks", "born": 1956 },
    { "id": 2, "name": "Robin Wright", "born": 1966 },
    { "id": 3, "name": "Gary Sinise", "born": 1955 }
  ]
}

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Limitations

  • Experimental: This feature may change or be removed in future versions.
  • No remote sharding: Foreign keys are not supported in environments using remote sharding.
  • One direction: Hydration works from the main index to the referenced index. The referenced index does not automatically link back.

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Next steps

Foreign keys settings API

Full API reference for foreign key settings

Experimental features API

Enable and manage experimental features

Indexing overview

Learn more about how indexing works in Meilisearch