如何在MongoDB的Java驅動程序

Question

ID字段寫入多個組在下面的查詢

{ $group : { 
     _id : { success:'$success', responseCode:'$responseCode', label:'$label'}, 
     max_timeStamp : { $timeStamp : 1 }, 
     count_responseCode : { $sum : 1 }, 
     avg_value : { $sum : "$value" }, 
     count_success : { $sum : 1 } 
    }} 

如何_id : { success:'$success', responseCode:'$responseCode', label:'$label'},可以翻譯在java中的MongoDB驅動程序才能使用。

我試圖

BasicDBList list = new BasicDBList(); 
list.add(new BasicDBObject("success", "$success")); 
list.add(new BasicDBObject("responseCode", "$responseCode")); 
list.add(new BasicDBObject("label", "$label")); 
AggregationOutput output = collection.aggregate(match, project, group); 

和

多維數組

String [][] muitiGroupBy = {{"success", "$success"},{"responseCode", "$responseCode"},{"label", "$label"}}; 

等。

但我總是得到這樣的結果

"_id" : [ { "success" : "$success"} , { "responseCode" : "$responseCode"}] 

如果我只使用一個領域它的作品。 DBObject groupFields = new BasicDBObject（「_id」，new BasicDBObject（「success」，「$ success」））;}};}};}};

Answer 1

我們弄清楚了方法。我們可以通過使用this來實現。

Map<String, Object> dbObjIdMap = new HashMap<String, Object>(); 
dbObjIdMap.put("success", "$success"); 
dbObjIdMap.put("responseCode", "$responseCode"); 
dbObjIdMap.put("label", "$label"); 
DBObject groupFields = new BasicDBObject("_id", new BasicDBObject(dbObjIdMap)); 

Answer 2

我可以通過這個代碼（代碼的Grails和蒙戈-Java的應用程序-3.2）實現這一點：

DBObject groupFields = new BasicDBObject() 
groupFields.put('success', "\$success") 
groupFields.put('responseCode', "\$responseCode") 
groupFields.put('label', "\$label") 
def result = collection.aggregate(Arrays.asList(Aggregates.group(groupFields, []))).iterator()