scala - elemMatch 使用 $gt 和 $lt 查询

Question

我正在尝试使用Casbah$gt和$lt在 Casbah 中实现 elemMatch 查询。

"Testing $gt and $lt in $elemMatch" should "return results" in { 

val TEST = "test"

val db = MongoClient()(TEST)
val collection = db(TEST)

val obj: JsValue = Json.parse("""{ "records" : [{"n" : "Name", "age": 5}]}""")
val doc: DBObject = JSON.parse(obj.toString).asInstanceOf[DBObject]

collection.insert(doc)

val elemMatch = "records" $elemMatch (MongoDBObject("n" -> "Name", "age" $gt 0))
val results = collection.find(elemMatch, MongoDBObject("_id" -> 1))

在线上val elemMatch，我看到了这个编译时错误：

[error] ...\TestElemMatch.scala:51: ')' expected but integer
 literal found.
[error]         val elemMatch = "records" $elemMatch (MongoDBObject("n" -> "Name", "age" -> $gt 0))
                                                                                   ^

http://docs.mongodb.org/manual/reference/operator/query/elemMatch/

Answer 1

运算符 $gt 的使用方式不正确，这应该可以

val elemMatch = MongoDBObject("records" -> MongoDBObject("$elemMatch" -> MongoDBObject("n" -> "Name", "age"->MongoDBObject("$gt"-> 0))))