将新字段添加到mongoDB嵌入文档

Question

我有一个类似这样的mongoDocument结构，注释字段作为嵌入文档。

我想添加 “newField” ： “something” 到 嵌入的注释字段中 “cid” ： “17426944” ：

在java驱动程序中，我尝试了:

BasicDBObject query = new BasicDBObject();  // MongoDB query
BasicDBObject record = new BasicDBObject(); // MongoDB record
BasicDBObject dbObject = new BasicDBObject(); // fieldsToUpdate

query.put("comments.cid","17426944");
dbObject.put("comments.newField","something");
record.put("$set",dbObject );
mongoCtrl.updateCollection(query, record, false, true);  // mongoCtrl is my connection contrl

这里的问题是：

com.mongodb.MongoException: cannot use the part (comments of comments.newField) to traverse the element ({comments:[ ..........  ]})
    at com.mongodb.CommandResult.getException(CommandResult.java:100)
    at com.mongodb.CommandResult.throwOnError(CommandResult.java:134)
    at com.mongodb.DBTCPConnector._checkWriteError(DBTCPConnector.java:142)

示例文档：

{       
        "_id" : ObjectId("53abb8d17bfd6b92e2398d34"),
        "name" : "satish",
        "number": "1122112",
         "comments" : [
                {
                        "cid" : "17426944"                          
                },
                {
                        "cid" : "607395840"
                },
                {
                        "cid" : "393084416"
                }
        ]
}

我需要什么 ：

{       
        "_id" : ObjectId("53abb8d17bfd6b92e2398d34"),
        "name" : "satish",
        "number": "1122112",
         "comments" : [
                {
                        "cid" : "17426944",
                         "newField" : "something"       
                },
                {
                        "cid" : "607395840"
                },
                {
                        "cid" : "393084416"
                }
        ]
}

请帮帮我，谢谢vijay

Answer 1

非常接近，您只是错过了位置 $ 运算符来匹配在查询部分中找到的数组的位置：

BasicDBObject query = new BasicDBObject();  // MongoDB query
BasicDBObject record = new BasicDBObject(); // MongoDB record
BasicDBObject dbObject = new BasicDBObject(); // fieldsToUpdate

query.put("comments.cid","17426944");
dbObject.put("comments.$.newField","something");
record.put("$set",dbObject );
mongoCtrl.updateCollection(query, record, false, true);