mongoTemplate关联查询

//主表c_stu_homework关联两张表c_course和c_category，localField（）从表关联条件，foreignField（）主表的关联条件，as()别名
LookupOperation courseLookupOperation = LookupOperation.newLookup().
        from("c_course").
        localField("courseId").
        foreignField("id").
        as("course");

LookupOperation categoryLookupOperation = LookupOperation.newLookup().
        from("c_category").
        localField("homewkId").
        foreignField("homewkId").
        as("category");

String startDate = DateUtils.dateToString1(new Date()) + " 00:00:00";
String endDate = DateUtils.dateToString1(new Date()) + " 23:59:59";

//条件和查询的字段
Criteria cri = Criteria.where("createTime").gte(startDate).lte(endDate);
AggregationOperation match = Aggregation.match(cri);
ProjectionOperation project = Aggregation.project("id", "stuId", "homewkId", "homewkName", "category.categoryName", "completeStatus", "score", "createTime", "endTime", "courseId", "course.courseName", "orgId", "tchId", "tchName", "courseUnitId", "course.textbookId", "course.textbookVersionId", "course.textLevelId");

//将以上的条件封装
List<AggregationOperation> operations = new ArrayList<>();
operations.add(courseLookupOperation);
operations.add(categoryLookupOperation);
operations.add(match);
operations.add(project);

Aggregation aggregation = Aggregation.newAggregation(operations);
AggregationResults<StudentHomeEntity> results = mongoTemplate.aggregate(aggregation, "c_stu_homework", StudentHomeEntity.class);

List<StudentHomeEntity> mappedResults = results.getMappedResults();