Spring Data MongoDB outputType用于聚合不映射/不日志记录

Question

我试图将聚合操作的结果映射到DTO。它没有正确地映射，并且没有错误或日志消息来指示什么/哪里出错。

db.barProperty.aggregate([
{
$match: { domainObjectId : "044f4c4c-d481-4461-ae2f-301c78ff5c91"}
},
{
$sort: {
priority: 1,
issuedAt: -1
}
},
{
$group: {
"_id": "$field",
"value": {"$last": "$value"},
"issuedAt": {"$last": "$issuedAt"}
}
}
], { allowDiskUse: true });

/* 1 */
{
    "_id" : "field1",
    "value" : "2021-04-05T12:15:00Z",
    "issuedAt" : ISODate("2021-06-14T00:10:00.000Z")
}

/* 2 */
{
    "_id" : "field2",
    "value" : "value2",
    "issuedAt" : ISODate("2021-06-14T00:10:00.000Z")
}

    return reactiveMongoTemplate.aggregate(Aggregation.newAggregation(BarProperty.class,
                    Aggregation.match(Criteria.where("domainObjectId").is(domainObjectId)),
                    Aggregation.sort(Direction.DESC, PRIORITY)
                            .and(Direction.ASC, ISSUED_AT),
                    Aggregation.group("field")
                            .last(VALUE).as(VALUE)
                            .last(ISSUED_AT).as(ISSUED_AT)
            ).withOptions(AggregationOptions.builder().allowDiskUse(true).build()), ProjectionProperty.class)
            // TODO why is no ProjectionProperty being returned
            .doOnNext(c -> {
                System.out.println("found projection property");
            })
            .collectList();


@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class ProjectionProperty {

    private String id;

    private String value;

    private OffsetDateTime issuedAt;
}

我已经试过_ID了；和字段作为id字段的替代品。

Answer 1

请您首先确定您的聚合是否有效，并返回一个文档，而不是试图映射到DTO。

现在不要使用doNext（）。一步一步地接近它，找出它到底失败在哪里

Flux<Document> result = reactiveMongoTemplate.aggregate(agg, BarProperty.class, Document.class);