我目前正在使用Casbah和MongoDB来实现Web服务。到目前为止我没有遇到任何问题。我也在使用Scala。
然而，我很想知道是否有比Casbah更好的东西来做很多find / findOne类型的查询。
我遇到了Rogue，这是一种基于类型安全的基于Scala的DSL，它可以使查询更容易，更易读。
所以，我想知道转移到Rogue是否有用，这样随着Web服务项目变得更大，更复杂，Rogue支持查询会有所帮助吗？
只是想知道我是应该继续还是转向更好的事情。
答案 0 :(得分：12)
目前，Rogue只对Lift's MongoDB-Record系统起作用。
它提供完全类型安全性的部分原因是它为Lift-Record使用强大，定义良好的对象结构。由于您拥有完整的结构，因此您执行“自由格式”查询的能力要低得多。这就是我最近为Scala网络研讨会做的Lift-Record + Rogue演示的意思。 Lift＆amp; amp;和Rogue自从我这样做以后代码可能会稍微过时但仍然具有代表性。这是MongoDB的Lift-Record模型：
object LiftRecordDemo extends Application {
// We'll use enums for Type and Subtype
object EventType extends Enumeration {
type EventType = Value
val Conference, Webinar = Value
}
object EventSubType extends Enumeration {
type EventSubType = Value
val FullDay = Value("Full Day")
val HalfDay = Value("Half Day")
}
class MongoEvent extends MongoRecord[MongoEvent] with MongoId[MongoEvent] {
def meta = MongoEvent
object name extends StringField(this, 255)
object eventType extends EnumField(this, EventType)
object eventSubType extends OptionalEnumField(this, EventSubType)
object location extends JsonObjectField[MongoEvent, EventLocation](this, EventLocation) {
def defaultValue = EventLocation(None, None, None, None, None, None, None)
}
object hashtag extends OptionalStringField(this, 32)
object language extends OptionalStringField(this, 32)
object date extends JsonObjectField[MongoEvent, EventDate](this, EventDate) {
def defaultValue = EventDate(new DateTime, None)
}
object url extends OptionalStringField(this, 255)
object presenter extends OptionalStringField(this, 255)
}
object MongoEvent extends MongoEvent with MongoMetaRecord[MongoEvent] {
override def collectionName = "mongoEvents"
override def formats = super.formats + new EnumSerializer(EventType) + new EnumSerializer(EventSubType)
}
case class EventLocation(val venueName: Option[String], val url: Option[String], val address: Option[String], val city: Option[String], val state: Option[String], val zip: Option[String], val country: Option[String]) extends JsonObject[EventLocation] {
def meta = EventLocation
}
object EventLocation extends JsonObjectMeta[EventLocation]
case class EventDate(start: DateTime, end: Option[DateTime]) extends JsonObject[EventDate] {
def meta = EventDate
}
object EventDate extends JsonObjectMeta[EventDate]
}
正如您所看到的，您需要提前定义MongoDB数据模型，以获得强类型，安全查询的好处...... Rogue在编译时强制执行大部分操作。以下是针对此模型的一些Rogue示例：
// Tell Lift about our DB
val mongoAddr = MongoAddress(MongoHost("127.0.0.1", 27017), "scalaWebinar")
MongoDB.defineDb(DefaultMongoIdentifier, mongoAddr)
// Rogue gives us a saner approach, although still hobbled by some
// of Lift-MongoDB-Record's limits on embedded docs
val q = MongoEvent where (_.eventType eqs EventType.Webinar)
println("Rogue created a Query '%s'\n\n".format(q))
for (x <- MongoEvent where (_.eventType eqs EventType.Webinar)) {
println("Name: %s Presenter: %s\n".format(x.name, x.presenter))
}
// Rogue can also do sorting for you, which is useful
println("\n\n\n")
for (x <- MongoEvent where (_.eventType eqs EventType.Conference)
orderAsc(_.language) andDesc(_.name)) {
println("Name: %s Language: %s\n".format(x.name, x.language))
}
val start = new DateTime(2011, 2, 1, 0, 0, 0, 0)
val end = new DateTime(2011, 3, 1, 0, 0, 0, 0)
/** The following would be nice but unfortunately,
doesn't work because of lift's current embedded doc
implementation
*/
//val dateQ = MongoEvent where (_.date.start after start)
//and (_.date.end before end)
请注意，我并不是说Rogue和Lift-Record不是很棒，只是说它们使用强大的编译时数据模型。
如果您想使用与Casbah类似的上下文，我们确实有一个内置DSL，旨在尽可能地模仿MongoDB的内置Query模型。它适用于任何任意底层模型，但是尽可能强制执行类型安全级别。这是Casbah的查询的一个例子（稍微过时，来自同一个演示文稿）：
// What about querying? Lets find all the non-US events
for (x <- mongo.find(MongoDBObject("location.country" ->
MongoDBObject("$ne" -> "USA")))) println(x)
/* There's a problem here: We got back the Webinars too because
They don't have a country at all, so they aren't "USA"
*/
println("\n\nTesting for existence of Location.Country:")
for (x <- mongo.find(MongoDBObject("location.country" -> MongoDBObject(
"$ne" -> "USA",
"$exists" -> true
)))) println(x)
// This is getting a bit unwieldy. Thankfully, Casbah offers a DSL
val q = $or ("location.country" -> "USA", "location.country" -> "Japan")
println("\n Created a DBObject: %s".format(q))
println("\n Querying using DSL Object...")
for (x <- mongo.find(q)) println(x)
// It's possible to construct more complex queries too.
// Lets find everything in February
println("\n February Events...")
val start = new DateTime(2011, 2, 1, 0, 0, 0, 0)
val end = new DateTime(2011, 3, 1, 0, 0, 0, 0)
val dateQ = "date.start" $gte start $lt end
println("\n Date Query: %s".format(dateQ))
for (x <- mongo.find(dateQ, MongoDBObject("name" -> true, "date" -> true))) println(x)
值得注意的是，我们正在查询自由格式模型，但使用DSL运算符而不是嵌套的MongoDB定义。运算符有很多奇妙的映射，直到$ type运算符，使用类清单测试类型以确保编译时安全：
"Casbah's $type operator" should {
"Accept raw Byte indicators (e.g. from org.bson.BSON)" in {
// Don't need to test every value here since it's just a byte
val typeOper = "foo" $type org.bson.BSON.NUMBER_LONG
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.NUMBER_LONG))
}
"Accept manifested Type arguments" in {
"Doubles" in {
val typeOper = "foo".$type[Double]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.NUMBER))
}
"Strings" in {
val typeOper = "foo".$type[String]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.STRING))
}
"Object" in {
"via BSONObject" in {
val typeOper = "foo".$type[org.bson.BSONObject]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.OBJECT))
}
"via DBObject" in {
val typeOper = "foo".$type[DBObject]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.OBJECT))
}
}
"Array" in {
"via BasicDBList" in {
val typeOper = "foo".$type[BasicDBList]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.ARRAY))
}
"via BasicBSONList" in {
val typeOper = "foo".$type[org.bson.types.BasicBSONList]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.ARRAY))
}
}
"OID" in {
val typeOper = "foo".$type[ObjectId]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.OID))
}
"Boolean" in {
val typeOper = "foo".$type[Boolean]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.BOOLEAN))
}
"Date" in {
"via JDKDate" in {
val typeOper = "foo".$type[java.util.Date]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.DATE))
}
"via Joda DateTime" in {
val typeOper = "foo".$type[org.joda.time.DateTime]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.DATE))
}
}
"None (null)" in {
// For some reason you can't use NONE
val typeOper = "foo".$type[Option[Nothing]]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.NULL))
}
"Regex" in {
"Scala Regex" in {
val typeOper = "foo".$type[scala.util.matching.Regex]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.REGEX))
}
}
"Symbol" in {
val typeOper = "foo".$type[Symbol]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.SYMBOL))
}
"Number (integer)" in {
val typeOper = "foo".$type[Int]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.NUMBER_INT))
}
"Number (Long)" in {
val typeOper = "foo".$type[Long]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.NUMBER_LONG))
}
"Timestamp" in {
val typeOper = "foo".$type[java.sql.Timestamp]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.TIMESTAMP))
}
"Binary" in {
val typeOper = "foo".$type[Array[Byte]]
typeOper must notBeNull
typeOper.toString must notBeNull
typeOper must haveSuperClass[DBObject]
typeOper must beEqualTo(nonDSL("foo", "$type", org.bson.BSON.BINARY))
}
}
（注意：您需要将casbah-query软件包及其相关的导入导入到您的代码中，或者使用预模块化的默认“casbah”导入）。目前Casbah的规格已经覆盖了每个DSL运营商;目前这些文档落后了，但规范是对其使用的一个很好的介绍。注意Casbah中有两种种类的运算符，就像在MongoDB中一样。
Bareword Operators ，其中语句的最左边部分是 $ Operator 。例如
$set，$rename等。有关详情，请参阅the Specs for Bareword Operators。“核心”操作符是语句右侧存在的运算符，例如
$type。有关详情，请参阅the Specs for Core Operators。
我知道这是一个相当详细的答案，但我想确保您了解您的选择，以及两种解决方案的局限性。 Casbah将为您提供一个与MongoDB紧密相关的DSL，并删除一些语法残骸（请记住，Casbah还在getAs[T]上提供DBObject方法，要求DBObject中的值作为特定的类型，人们经常忽略它们;许多用户在寻求内容之前不知道DSL存在。然而，Casbah的查询DSL在一些人的意见中看起来有点“狡猾”......作为它的作者我更喜欢它的简单和优雅，因为我只需要记住用于查询的** MONGODB *语法，而不是MongoDB和另一个DSL。它也基于自由格式查询，并且不提供相同的结构化编译时类型安全＆amp;意识到Rogue所做的设施。
相比之下，Rogue还需要一个完全定义的Record模型，它不适合每个应用程序。
我很乐意听到，如果有任何产品无法满足您的需求的“中间立场”，那么任何产品都可以改进。