Question

我收到以下错误： com.mongodb.MongoCommandException：命令失败，错误139：＆＃39; SyntaxError：missing;在陈述@：1：60之前＆＃39;在服务器localhost：27017。完整的回答是{＆＃34; ok＆＃34; ：0.0，＆＃34; errmsg＆＃34; ：＆＃34; SyntaxError：missing;在陈述@：1：60 \ n＆＃34;，＆＃34;代码＆＃34; ：139

似乎我错过了一个;但似乎无法看到哪里。该方法不言自明，我倾向于通过mongo创建map / reduce。任何帮助表示赞赏。

public void mapFunction()
           {
               Mongo mongo = null;
               try{
               mongo = new Mongo("localhost", 27017);
               DB db = mongo.getDB("amarokforumdb");

               DBCollection comments = db.getCollection("comments");  
               String map = "function() { "+
                     "var category; " + 
                         "var numOfDocuments = "+db+".comments.count();" +

                         "for(i = 0; i < numOfDocuments; i++){ " +
                     "if (numOfDocuments <= 100) {"+ 
                     "category = 'New Comments'; }" +
                     "else if(numOfDocuments > 100){" +
                     "category = 'Old Comments'; }}"+ 
                     "emit(category,1);};";

               String reduce = "function(key, values) { " +
                                    "var sum = 0; " +
                                    "values.forEach(function(doc) { " +
                                    "sum += 1; "+
                                    "}); " +
                                    "return {comments: sum};} ";


                MapReduceCommand cmd = new MapReduceCommand(comments, map, reduce,
            null, MapReduceCommand.OutputType.INLINE, null);

            MapReduceOutput out = comments.mapReduce(cmd);



               for (DBObject o : out.results()) {
            System.out.println(o.toString());
               }}catch (Exception e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
          }

           }

Answer 1

将"+db+".comments.count();替换为整数以进行测试，我认为您+db+部分出了问题

Mongo / Java Map-Reduce函数 - MongoCommandException

1 个答案: