Morphai阵列切片[聚合管道]

Question

{ $project: { _id: 1, facets: { $slice: [ "$facets", 0,1] } } }

AggregationPipeline pipeline = ds.createAggregation
pipeline.project()

需要在morphia中编写这个mongo db查询[AggregationPipeline.project]

请你帮我在morphia

中写这个查询

ArraySlice slice=new ArraySlice(searchRequisitionRequestBean.getOffset(),
    searchRequisitionRequestBean‌​.getLimit());
Query<Requisition> sliceQuery = ds.createQuery(Requisition.class);
sliceQuery.project("_id", true);
sliceQuery.project("facets", slice);
pipeline.project(sliceQuery.getQueryObject());