您可以将
$exists运算符与
.符号结合使用。mongo-shell中的裸查询应如下所示：
db.yourcollection.find({ 'otherInfo.text' : { '$exists' : true }})Java中的测试用例可能如下所示：
BasicDBObject dbo = new BasicDBObject(); dbo.put("name", "first"); collection.insert(dbo); dbo.put("_id", null); dbo.put("name", "second"); dbo.put("otherInfo", new BasicDBObject("text", "sometext")); collection.insert(dbo); DBObject query = new BasicDBObject("otherInfo.text", new BasicDBObject("$exists", true)); DBCursor result = collection.find(query); System.out.println(result.size()); System.out.println(result.iterator().next());输出：
1{ "_id" : { "$oid" : "4f809e72764d280cf6ee6099"} , "name" : "second" , "otherInfo" : { "text" : "sometext"}}
