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如何从mongodb的内部文档获取字段?例如,如果我给一个名为“idMovie”的字段,我会得到与此idMovie相对应的字段的其余部分。从mongodb的内部文档中的数组获取值
我使用这个代码:
MongoClient mongo = null;
DBCursor cursor = null;
String average = "";
String sum = "";
String numCal = "";
try {
mongo = new MongoClient ("localhost", 27017);
DB db = mongo.getDB("DBHC2");
DBCollection movieDocument = db.getCollection("movies");
BasicDBObject searchQuery = new BasicDBObject();
searchQuery.put("rateMovies.idMovie", idMovie);
cursor = movieDocument.find(searchQuery);
if(cursor.hasNext()){
average = searchQuery.getString("average");
sum = searchQuery.getString("sum");
numCal = searchQuery.getString("total");
System.out.println("***** Debug: average: "+average+" sum: "+sum+" total: "+numCal);
}
}
catch(Exception e){
System.out.println("error : " + e.getMessage());
System.out.println("error : " + e.getCause());
}
finally{
cursor.close();
}
}
当我运行它,在控制台打印:
***** Debug: average: null sum: null total: null
这是我使用MongoDB的文档:
{ "_id" : { "$oid" : "5320aa3c3e468eaeb52dccdc"},
"document" : "movies" ,
"rateMovies" : [
{
"idMovie" : 2 ,
"average" : "0" ,
"sum" : "0" ,
"total" : "0"
} ,
{
"idMovie" : 3 ,
"average" : "0" ,
"sum" : "0" ,
"total" : "0"
}]
}
预先感谢您! :) 对不起我的英语不好。
我试图做到这一点,没有成功:'如果(cursor.hasNext()){ \t \t \t \t \t \t \t \t DBOBJECT resultElement = cursor.next(); \t \t \t \t average =(String)resultElement.get(“average”); \t \t \t \t id =(String)resultElement.get(“idMovie”); \t \t \t \t sum =(String)resultElement.get(“sum”); \t \t \t \t numCal =(字符串)resultElement.get( “总”);' – HCarrasko
你会需要这样的东西: DBOBJECT resultElement = cursor.next(); 列表 list =(列表)resultElement.get(“rateMovies”); //遍历这个列表来拉你的平均值 –
evanchooly
我会试试,谢谢! – HCarrasko