在我的 MongoDB 图书收藏中,我的文档结构如下:
/* 0 */
{
"_id" : ObjectId("50485b89b30f1ea69110ff4c"),
"publisher" : {
"$ref" : "boohya",
"$id" : "foo"
},
"displayName" : "Paris Nightlife",
"catalogDescription" : "Some desc goes here",
"languageCode" : "en",
"rating" : 0,
"status" : "LIVE",
"thumbnailId" : ObjectId("50485b89b30f1ea69110ff4b"),
"indexTokens" : ["Nightlife", "Paris"]
}
我执行以下正则表达式查询,以查找所有具有以“Par”开头的一个索引标记的文档:
{ "indexTokens" : { "$regex" : "^Par" , "$options" : "i"}}
如果我像这样仅选择返回indexTokens字段:{ "indexTokens" : 1}
The resulting DBObject is{ "_id" : { "$oid" : "50485b89b30f1ea69110ff4c"} , "indexTokens" : [ "Nightlife" , "Paris"]}
我想要的仅是与正则表达式匹配的标记/标签(此时我不关心检索文档,也不需要匹配文档的所有标记)
这是否适用于MongoDB v2.2发布的新聚合框架?
如果是,我应该如何修改查询,以便实际结果看起来像:
{"indexTokens":["Paris","Paradise River","Parma"等]}
奖励问题(你有代码吗):如何使用Java驱动程序进行操作?
目前我的Java代码类似于:
DBObject query = new BasicDBObject("indexTokens", java.util.regex.Pattern.compile("^"+filter+"", Pattern.CASE_INSENSITIVE));
BasicDBObject fields = new BasicDBObject("indexTokens",1);
DBCursor curs = getCollection()
.find(query, fields)
.sort( new BasicDBObject( "indexTokens" , 1 ))
.limit(maxSuggestionCount);
谢谢:)
编辑:
根据您的答复,我已修改了我的JAVA代码如下:
BasicDBObject cmdBody = new BasicDBObject("aggregate", "Book");
ArrayList<BasicDBObject> pipeline = new ArrayList<BasicDBObject>();
BasicDBObject match = new BasicDBObject("$match", new BasicDBObject("indexTokens", java.util.regex.Pattern.compile("^"+titleFilter+"", Pattern.CASE_INSENSITIVE)));
BasicDBObject unwind = new BasicDBObject("$unwind", "$indexTokens");
BasicDBObject match2 = new BasicDBObject("$match", new BasicDBObject("indexTokens", java.util.regex.Pattern.compile("^"+titleFilter+"", Pattern.CASE_INSENSITIVE)));
BasicDBObject groupFilters = new BasicDBObject("_id",null);
groupFilters.append("indexTokens", new BasicDBObject( "$push", "$indexTokens"));
BasicDBObject group = new BasicDBObject("$group", groupFilters);
pipeline.add(match);
pipeline.add(unwind);
pipeline.add(match2);
pipeline.add(group);
cmdBody.put("pipeline", pipeline);
CommandResult res = getCollection().getDB().command(cmdBody);
System.out.println(res);
输出结果为
{ "result" : [ { "_id" : null , "indexTokens" : [ "Paris"]}] , "ok" : 1.0}
这太聪明了!
非常感谢!