java - 如何在mongoquery中展开两个数组

Question

我在 mongodb 中有一个这样的集合:

{
"_id" : ObjectId("5490a00879dc6a138dcefb0f"),
"Date" : 20141012,
"Type" : "Twitter",
"Entities" : [ 
    {
        "ID" : 2,
        "Name" : "test1",
        "Sentiment" : {
            "Value" : 0.1,
            "Neutral" : 12
        }
     }
],
"Topics" : [ 
    {
        "ID" : 1,
        "Name" : "Test2",
        "Sentiment" : {
            "Value" : 0.5,
            "Neutral" : 1
        }
    }
]
}

现在我需要展开主题和实体数组，然后我想按日期分组并对情绪的所有值求和，所以我按如下方式进行:

    DBObject unwind = new BasicDBObject("$unwind", "$Entities"); 
    unwind.put("$unwind", "$Topics");
    collectionG = db.getCollection("GraphDataCollection");
    DBObject groupFields = new BasicDBObject( "_id", "$Date");
    groupFields.put("value", new BasicDBObject( "$sum", "$Entities.Sentiment.Value"));
    DBObject groupBy = new BasicDBObject("$group", groupFields );
    AggregationOutput output = collectionG.aggregate(where,unwind, groupBy);

现在的问题是，对于情绪值的总和，只返回 0，但如果我删除以下行:

    unwind.put("$unwind", "$Topics");

它工作正常，所以我的问题是如何通过一个聚合展开两个数组？

更新:

我改变了我的代码如下:

DBObject unwind = new BasicDBObject("$unwind", "$Entities"); // "$unwind" converts object with array into many duplicate objects, each with one from array
    DBObject unwindT = new BasicDBObject("$unwind", "$Topics"); // "$unwind" converts object with array into many duplicate objects, each with one from array
    collectionG = db.getCollection("GraphDataCollection");
    DBObject groupFields = new BasicDBObject( "_id", "$Date");
   groupFields.put("value", new BasicDBObject( "$sum", "$Entities.Sentiment.Value"));
    groupFields.put("value1", new BasicDBObject( "$sum", "$Topics.Sentiment.Value"));
    DBObject groupBy = new BasicDBObject("$group", groupFields );
    List<DBObject> pipeline = Arrays.asList(unwind, unwindT);
    DBObject sort = new BasicDBObject("$sort", new BasicDBObject("_id", 1));
    AggregationOutput output = collectionG.aggregate(where,unwind,unwindT, groupBy,sort);

但问题是一旦我添加以下行:

groupFields.put("value1", new BasicDBObject( "$sum", "$Topics.Sentiment.Value"));

返回的 value1 和 value 的数字不正确，我认为我没有正确展开。谁能帮忙？

Answer 1

另一种方法，

• Unwind Entities 数组。
• Group 按_id，得到Entities 的sum。
• Unwind Topics 数组。
• Group 按 _id，得到 Topics 的总和。
• Project 一个字段来显示topics 和entities 情绪的总和值(value)观。
• Group 按 Date 得到 Netty 。

这样，每个管道中的文档数量最少，并且不会涉及太多的自连接。

聚合代码:

db.collection.aggregate([
{$unwind:"$Entities"},
{$group:{"_id":"$_id",
         "Date":{$first:"$Date"},
         "Topics":{$first:"$Topics"},
         "EntitiesSum":{$sum:"$Entities.Sentiment.Value"}}},
{$unwind:"$Topics"},
{$group:{"_id":"$_id",
         "Date":{$first:"$Date"},
         "EntitiesSum":{$first:"$EntitiesSum"},
         "TopicsSum":{$sum:"$Topics.Sentiment.Value"}}},
{$project:{"_id":0,"Date":1,"EntitiesSum":1,"TopicsSum":1,
           "indSum":{$add:["$EntitiesSum","$TopicsSum"]}}},
{$group:{"_id":"$Date",
         "EntitiesSentimentSum":{$sum:"$EntitiesSum"},
         "TopicsSentimentSum":{$sum:"$TopicsSum"},
         "netSentimentSum":{$sum:"$indSum"}}}
])

Java 等价物:

     DBObject unwindEntities = new BasicDBObject("$unwind","$Entities");

     DBObject groupSameIdEntities = new BasicDBObject("_id","$_id");
     groupSameIdEntities.put("Date", new BasicDBObject("$first","$Date"));
     groupSameIdEntities.put("Topics", new BasicDBObject("$first","$Topics"));
     groupSameIdEntities.put("EntitiesSum", 
                    new BasicDBObject("$sum","$Entities.Sentiment.Value"));


     DBObject unwindTopics = new BasicDBObject("$unwind","$Topics");

     DBObject groupSameIdTopics = new BasicDBObject("_id","$_id");
     groupSameIdTopics.put("Date", new BasicDBObject("$first","$Date"));
     groupSameIdTopics.put("EntitiesSum", 
                         new BasicDBObject("$first","$EntitiesSum"));
     groupSameIdTopics.put("TopicsSum",
                        new BasicDBObject("$sum","$Topics.Sentiment.Value"));

     DBObject project = new BasicDBObject("_id",0);
     project.put("Date",1);
     project.put("EntitiesSum",1);
     project.put("TopicsSum",1);
     project.put("netSumPerId",
             new BasicDBObject("$add",
                   new String[]{"$EntitiesSum","$TopicsSum"}));

     DBObject groupByDate = new BasicDBObject("_id","$Date");
     groupByDate.put("EntitiesSentimentSum", 
                     new BasicDBObject("$sum","$EntitiesSum"));
     groupByDate.put("TopicsSentimentSum", 
                     new BasicDBObject("$sum","$TopicsSum"));
     groupByDate.put("netSentimentSum", 
                      new BasicDBObject("$sum","$netSumPerId"));

     AggregationOutput output = col.aggregate(unwindEntities,
                                new BasicDBObject("$group",
                                             groupSameIdEntities),
                                unwindTopics,
                                new BasicDBObject("$group",groupSameIdTopics),
                                new BasicDBObject("$project",project),
                                new BasicDBObject("$group",groupByDate));

示例 o/p(有两个文档):

{ "_id" : 2.0141012E7, 
"EntitiesSentimentSum" : 0.30000000000000004 ,
"TopicsSentimentSum" : 1.2 , 
"netSentimentSum" : 1.5}

请将日期字段保存为 ISODate()。