$lookup

Menyusun alur simple join dan LookupSpec berbasis let/pipeline, tahap mentah native Driver, unwind dan hitung lookup.

localField / foreignField

java

let + pipeline + $expr

java

• bindConditionFields(leftField, condition, rightField)

• bindConditionFieldsLeftToObjectId(...)

• bindConditionExists, bindConditionIsNull, bindConditionIsNotNull

• bindConditionConst, bindConditionBetween, bindConditionLike

• rawStage(Bson) untuk tahap pipeline lookup native Driver

• unwind(preserveNullAndEmptyArrays)

• outerStage(Bson) / outerStages(...) untuk tahap setelah $lookup

Menjalankan Lookup

java

unwind(...)를 사용하지 않은 기본 findAll lookup은 right 결과를 List<R>로 반환합니다. 단건 left/right가 필요하면 find().executeLookup(...) 경로를 사용합니다.

Lookup + hitung / ada

java

executeLookupAndCount(...) mengembalikan data dan totalCount dalam bentuk $facet(data, count). builder count/exists juga dapat menerima hasil lookup sebagai tuple kiri/kanan.