SharePoint Lookup column

Pointer to another list. Stored as an integer id; the write shape uses {Field}Id.

The Lookup column stores a foreign-key pointer to an item in another SharePoint list. The displayed value is the linked item's display column (configurable); the stored value is the linked item's integer id.

Binds to Lookup and

LookupControl.

Write shape

The SP REST API uses the {Field}Id suffix:

{ "CustomerId": 42 }

For multi-value lookups:

{ "TagsId": { "results": [1, 7, 12] } }

Edge cases

  • Cross-site lookups, Standard SP lookups only target lists in the same site collection. The runtime warns when configured against an out-of-scope list.
  • Indexed lookups, Performance-sensitive forms (large target lists, frequent re-renders) should ensure the Lookup column's target list has the display column indexed.

Related articles

  • Lookup field

    Search and pick from another SharePoint list, typeahead autocomplete with a configurable display column.

  • SharePoint User column (Person)

    People-picker column. Stored as a user id; same write shape as Lookup.