大家好,我正在用Java开发mongodb,我有一个场景,如果外部文档匹配,那么我必须在嵌套数组中更新/添加计数,例如,我想做这样的事情:
`"_id" : ObjectId("55d71603aed7562284e5df95"),"id" : "1","type" : "a","score" : { "mark1" : "1", "mark2" : "2", "count" : { "one","two" }}`
如果我再次发送具有相同字段的文档,例如id:1,请输入:a,mark1:1,mark2:2,那么我必须将我的文档作为
`"_id" : ObjectId("55d71603aed7562284e5df95"),"id" : "1","type" : "a","score" : { "mark1" : "1", "mark2" : "2", "count" : { "one","two","three" }}`
但是我得到这样的东西:
`"_id" : ObjectId("55d71e42aed7560e8c9d02e4"),"id" : "1","type" : "a","score" : { "mark1" : "1", "mark2" : "2", "count" : { "count" : "one", }}`
我的java代码是
`mongoDatabase=mongoClient.getDatabase("TestNestedInsert"); Document sourceDocument=mongoDatabase.getCollection("entity").find(new Document("id",1).append("score.mark1", "1").append("score.mark2", "2")).first(); if(sourceDocument==null){ Document entity=new Document(); entity.append("id", "1"); entity.append("type", "a"); entity.append("score", new Document("mark1","1").append("mark2", "2").append("count", new Document("count","one"))); mongoDatabase.getCollection("entity").insertOne(entity); } else{ mongoDatabase.getCollection("entity").findOneAndUpdate(new Document("id",1).append("score.mark1", "1").append("score.mark2", "2"), new Document("$set",new Document("score.count","three"))); } `
我知道我们不能有重复的键,我也尝试过$set和$push,但是我被卡住了.有什么帮助吗?
解决方法:
根据代码,主要问题在于“ count”键是一个对象而不是数组.因此正确的JSON表示为:
{ "_id": ObjectId("55d71603aed7562284e5df95"), "id": "1", "type": "a", "score": { "mark1": "1", "mark2": "2", "count": [ "one", "two", "three" ] }}
请注意“计数”键后面的方括号“ []”.
关于新的mongo java驱动程序(3.0),我有相同的问题.
这是我解决的方法:
MongoDatabase mongoDatabase = mongoClient.getDatabase("TestNestedInsert");MongoCollection<Document> entityCollection = mongoDatabase.getCollection("entity");Document queryDocument = new Document("id", 1).append("score.mark1", "1").append("score.mark2", "2");Document sourceDocument = entityCollection.find(queryDocument).first();if (sourceDocument == null) { Document entity = new Document(); entity.append("id", "1"); entity.append("type", "a"); // Create the score nested object String[] countArray = { "one", "two" }; // create the count array Document scoreObject = new Document() .append("mark1", "1") .append("mark2", "2") .append("count", countArray); // append the count array entity.append("score", scoreObject); // append the score object. entityCollection.insertOne(entity);}else{ // push the new element to the count array. // see: https://docs.mongodb.org/v3.0/reference/operator/update/push/#append-a-value-to-an-array Document elementToArray = new Document("score.count", "three"); Document pushElement = new Document("$push", elementToArray); entityCollection.updateOne(queryDocument, pushElement);}
希望能帮助到你!
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