Question

MongoDb + Spring boot + intersectsArrays

我想随机取15个用户并知道共同的兴趣。文档结构是这样的

{
    "_id": {
      "$oid": "593f773202338a47584b351e"
    },
    "interests": [
      {
        "_id": {
          "$oid": "5957933cf3c5f5253ec9476c"
        },
        "name": "abc1",
        "facebookId": "123"
      }]
    ]
  }

需要获取mongo返回的每个用户的共同兴趣。

以下是我的Spring启动代码

Criteria criteria = new Criteria().andOperator(Criteria.where("lastLoginDate").gte(Utility.getDateBeforeDays(lastLoginNewerThan)));
        Aggregation agg = Aggregation.newAggregation(new CustomAggregationOperation(maxRecords),
                Aggregation.match(criteria),Aggregation.project("id","name")
                );
        AggregationResults<Users> userResults = operations.aggregate(agg, Users.class, Users.class);
        List<Users> users = userResults.getMappedResults();

Answer 1

看起来Spring Mongo Data api没有提供将值列表作为输入传递给集合交集运算符的方法。

您可以使用AggressionExpression来提供自定义实现。请在项目阶段的下方投影。

.and(new AggregationExpression() {
       @Override
        public DBObject toDbObject(AggregationOperationContext context) {
            return new BasicDBObject("$setIntersection",
                Arrays.<Object> asList(
                     Arrays.<Object> asList("reading","movies"),
                         "$interests"));
            }
}).as("commonInterests"));

您可以将表达式包装为Java 8的lambda

and(context -> new BasicDBObject("$setIntersection",
            Arrays.<Object> asList(
                 Arrays.<Object> asList("reading","movies"),
                   "$interests")))
.as("commonInterests");

从两个记录中交叉mongodb

1 个答案: