Spring/spring-data-mongodb
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Refine @DocumentReference documentation about self._id references.

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Closes #4925
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Mark Paluch
2025-03-19 09:42:24 +01:00
parent b226c8e00e
commit 921d035f8d
1 changed files with 3 additions and 1 deletions
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src/main/antora/modules/ROOT/pages/mongodb/mapping/document-references.adoc
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@@ -487,7 +487,9 @@ We know it is tempting to use all kinds of MongoDB query operators in the lookup
But there a few aspects to consider:
* Make sure to have indexes in place that support your lookup.
* Mind that resolution requires a server rountrip inducing latency, consider a lazy strategy.
* Make sure to use the same data types: `@DocumentReference(lookup="{'someRef':?#{#self._id} }")` can easily fail when using `@Id String id` and `String someRef` as ``String @Id``'s are subject to automatic ObjectId conversion (but not other `String` properties containing `ObjectId.toString()`).
Reference lookup uses values from the resulting `Document` and in that case, it would query a String field using an `ObjectId` yielding no results.
* Mind that resolution requires a server roundtrip inducing latency, consider a lazy strategy.
* A collection of document references is bulk loaded using the `$or` operator. +
The original element order is restored in memory on a best-effort basis.
Restoring the order is only possible when using equality expressions and cannot be done when using MongoDB query operators.