I have a pre-existing database, and this code:
class User private() extends MongoRecord[User] with StringPk[User] {
def meta = User
object createdAt extends DateTimeField(this)
object lastLogin extends DateTimeField(this)
object password extends StringField(this, 128)
object salt extends StringField(this, 128)
}
object User extends User with MongoMetaRecord[User]
The problem is, in my database, the field createdAt is called created-at, and similar with lastLogin. Looking into the docs, there are several object fields that could be doing the job (label, name, title, uniqueFieldId), so which one would it be?
The member name seems to be the one looking for. As in
object createdAt extends DateTimeField(this) {
def name = "created-at"
}
Related
I'm trying out phantom from outworkers following the laidout tut on the wiki.
I'm using a test model:
case class User (id: String, name: String, friends: List[String])
with:
import com.websudos.phantom.dsl._
class Users extends CassandraTable[Users, User] {
object id extends StringColumn(this) with PartitionKey[String]
object name extends StringCoumn(this)
object friends extends ListColumn[String](this)
}
The ListColumn[String]() argument this is marked as an error which I presume I shouldnt even bother to build. Expected CassandraTable[String, User] instead of this.
I'm using version 1.29.6
Am I using a different version from the wiki example? Or missing something else?
This is an InteliJ highlightining problem. ListColumn is defined as a type alias inside Cassandra table, and for all type aliases that take constructor arguments, InteliJ is not capable of seeing through them.
That aside, I would really upgrade to phantom 2.0.0+, just because of all the new improvements made in 2.0.0. There is quite a bit of work that's gone into fixing errors and reducing how much code you need to type:
import com.outworkers.phantom.dsl._
class Users extends CassandraTable[Users, User] {
object id extends StringColumn(this) with PartitionKey
object name extends StringCoumn(this)
object friends extends ListColumn[String](this)
}
In more recent versions of phantom, 2.9.x+, the this argument is no longer required using the new compact DSL.
import com.outworkers.phantom.dsl._
abtract class Users extends Table[Users, User] {
object id extends StringColumn with PartitionKey
object name extends StringColumn
object friends extends ListColumn[String]
}
I'm using phantom to connect cassandra in play framework. Created the first class following the tutorial. Everything works fine.
case class User(id: String, page: Map[String,String])
sealed class Users extends CassandraTable[Users, User] {
object id extends StringColumn(this) with PartitionKey[String]
object page extends MapColumn[String,String](this)
def fromRow(row: Row): User = {
User(
id(row),
page(row)
)
}
}
abstract class ConcreteUsers extends Users with RootConnector {
def getById(page: String): Future[Option[User]] = {
select.where(_.id eqs id).one()
}
def create(id:String, kv:(String,String)): Future[ResultSet] = {
insert.value(_.id, id).value(_.page, Map(kv)).consistencyLevel_=(ConsistencyLevel.QUORUM).future()
}
}
class UserDB(val keyspace: KeySpaceDef) extends Database(keyspace) {
object users extends ConcreteUsers with keyspace.Connector
}
object UserDB extends ResourceAuthDB(conn) {
def createTable() {
Await.ready(users.create.ifNotExists().future(), 3.seconds)
}
}
However, when I try to create another table following the exact same way, play throws the exception when compile:
overriding method session in trait RootConnector of type => com.datastax.driver.core.Session;
How could I build create another table? Also can someone explain what causes the exception? Thanks.
EDIT
I moved the connection part together in one class:
class UserDB(val keyspace: KeySpaceDef) extends Database(keyspace) {
object users extends ConcreteUsers with keyspace.Connector
object auth extends ConcreteAuthInfo with keyspace.Connector
}
This time the error message is:
overriding object session in class AuthInfo; lazy value session in trait Connector of
type com.datastax.driver.core.Session cannot override final member
Hope the message helps identify the problem.
The only problem I see here is not to do with connectors, it's here:
def getById(page: String): Future[Option[User]] = {
select.where(_.id eqs id).one()
}
This should be:
def getById(page: String): Future[Option[User]] = {
select.where(_.id eqs page).one()
}
Try this, I was able to compile. Is RootConnector the default one or do you define another yourself?
It took me 6 hours to figure out the problem. It is because there is a column named "session" in the other table. It turns out that you need to be careful when selecting column names. "session" obviously gives the above exception. Cassandra also has a long list of reserved keywords. If you accidentally use one of them as your column name, phantom will not throw any exceptions (maybe it should?). I don't know if any other keywords are reserved in phantom. A list of them will be really helpful.
I need to make a web service that can will contain lists of objects. One list can contain objects of many types. Here, for example, I have a library of media items. Each item can be either a link or a video, each with their own metadata.
I want to do this with the Lift web framework, because I need something that compiles to WAR and I've used Lift before.
I thought that using MongoDB for this sort of storage would work as, by definition, it's supposed to be able to handle collections of heterogeneous items.
I can define types of BSON objects to be stored in Lift records, but I can't seem to stick away from creating only one type of object in one record/collection. Ideally, I'd like each "thing" (for lack of a better word) in my Library to be either a video or a link. For example:
[
{
"type" : "Video",
"title" : "Story",
"videoID" : "123ab4",
"description": "Feature-length epic",
"time" : 12.6
},
{
"type" : "link",
"url" : "http://www.google.com",
"title": "Search for stuff"
}
]
I should be able to do it with the right type of inheritance, but the way all of the record objects's parents inherit from the object throws me off. Can I get this to work? Having a collection of different things that Lift can use as such?
Here's what I have so far. I haven't tested it, but even if it works what it does is NOT what I want.
import net.liftweb.record._
import net.liftweb.record.field._
import net.liftweb.mongodb._
import net.liftweb.mongodb.record._
import net.liftweb.mongodb.record.field._
class VideoShelf private () extends BsonRecord[VideoShelf] {
def meta = VideoShelf
object title extends StringField (this, 256)
object videoID extends StringField (this, 32 )
object description extends StringField (this, 256)
object time extends DecimalField(this, 0 )
}
object VideoShelf extends VideoShelf with BsonMetaRecord[VideoShelf]
class LinkShelf private () extends BsonRecord[LinkShelf] {
def meta = LinkShelf
object url extends StringField(this, 128)
object title extends StringField(this, 256)
}
object LinkShelf extends LinkShelf with BsonMetaRecord[LinkShelf]
class MediaLibrary private () extends MongoRecord[MediaLibrary] with ObjectIdPk[MediaLibrary] {
def meta = MediaLibrary
///////////////////////////////////////
///////////////////////////////////////
// What I want is this record type to
// contain either of these:
///////////////////////////////////////
object videoshelf extends BsonRecordField(this, VideoShelf)
object linkshelf extends BsonRecordField(this, LinkShelf )
}
object MediaLibrary extends MediaLibrary with MongoMetaRecord[MediaLibrary]
How can I get this?
After seeking more, I found this post: https://groups.google.com/forum/#!topic/liftweb/LmkhvDgrgrI
That led me to this conclusion, which I think is correct, though it has not been tested yet. I may be missing some pieces for it to fully work.
import net.liftweb.record._
import net.liftweb.record.field._
import net.liftweb.mongodb._
import net.liftweb.mongodb.record._
import net.liftweb.mongodb.record.field._
/**
* The base record type for library objects.
*/
trait MediaLibrary[T <: MediaLibrary[T]] extends MongoRecord[T] with ObjectIdPk[T] {
self: T =>
}
/**
* Items in the library that are videos.
*/
class VideoItem extends MediaLibrary[VideoItem] {
def meta = VideoItem
object title extends StringField (this, 256)
object videoID extends StringField (this, 32 )
object description extends StringField (this, 256)
object time extends DecimalField(this, 0 )
}
object VideoItem extends VideoItem with MongoMetaRecord[VideoItem]
/**
* Items in the library that are links.
*/
class LinkItem extends MediaLibrary[LinkItem] {
def meta = LinkItem
object url extends StringField (this, 256)
object title extends StringField (this, 256)
}
object LinkItem extends LinkItem with MongoMetaRecord[LinkItem]
UPDATE
I've also just found out that there is a MongoDB-specific record that's a list of case classes. That seems to be exactly what I need! It's the power of Scala and Mongo being used hand in hand! That's what I wanted from the start. I'll have to try that tomorrow.
Let say I have 3 tables: Book, Author and BookAuthor.
Book has id, title
Author has id, name
BookAuthor has id, book_id, author_id
I want to find all authors of a book. Can anyone guide me how to do this with Lifts mapper syntax?
class Book extends LongKeyedMapper[Book]
with IdPK
with ManyToMany {
def getSingleton = Book
object title extends MappedString(this, 255)
object authors extends MappedManyToMany(
BookAuthors, BookAuthors.book, BookAuthors.author, Author)
}
object Book extends Book with LongKeyedMetaMapper[Book]
class Author extends LongKeyedMapper[Author]
with CreatedUpdated with IdPK
with ManyToMany {
def getSingleton = Author
object firstName extends MappedString(this, 255)
object lastName extends MappedText(this)
object email extends MappedEmail(this, 150)
object books extends MappedManyToMany( BookAuthors,
BookAuthors.author, BookAuthors.book, Book)
}
object Author extends Author with LongKeyedMetaMapper[Author]
val warandpeace = Book.create.title("War and Peace").saveMe
val fred = Author.create.firstName("Fred").saveMe
fred.books += warandpeace
fred.saveMe
val bob = Author.create.firstName("Bob").saveMe
bob.books += warandpeace
bob.saveMe
// then to find all the authors of the book:
val authors = warandpeace.authors
Here is the mapper for the book:
class Book extends LongKeyedMapper[Book] with IdPk with OneToMany[Long, Book] {
def getSingleton = Book
object title extends MappedString(this, 200)
object BookAuthor extends MappedOneToMany(BookAuthor, BookAuthor.id)
}
object Book extends Book with LongKeyedMetaMapper[Book]
The trait IdPk will take care of the id of Book. Then for BookAuthor:
class BookAuthor extends LongKeyedMapper[BookAuthor] with IdPk with OneToOne[Long, BookAuthor] {
def getSingleton = BookAuthor
object Author extends MappedOneToOne(Author, Author.id)
}
object BookAuthor extends BookAuthor with LongKeyedMetaMapper[BookAuthor]
Then for Author, a simple mapper:
class Author extends LongKeyedMapper[Author] with IdPk {
def getSingleton = Author
object name extends MappedString(this, 200)
}
object Author extends Author with LongKeyedMetaMapper[Author]
Then the call to find all authors of a book (here myBook ):
myBook.BookAuthor.map(x => x.Author.name)
If you want to make more complicated join requests without having to filter everything in Scala, you can always use DB and you can always find more info about mapper here.
I'm trying to implement a a relation for the user class modelling the "friends" concept with the Lift Mapper framework. My attempt goes something like this
object User extends User with MetaMegaProtoUser[User] {
override def dbTableName = "users" // define the DB table name
override def screenWrap = Full(<lift:surround with="default" at="content">
<lift:bind /></lift:surround>)
// define the order fields will appear in forms and output
override def fieldOrder = List(id, firstName, lastName, email,
locale, timezone, password)
// comment this line out to require email validations
override def skipEmailValidation = true
}
class User extends MegaProtoUser[User] with OneToMany[Long,User]
{
def getSingleton = User // what's the "meta" server
object friends extends MappedOneToMany(User, User.id)
}
but it fails to compile because of a type mismatch
[error] src/main/scala/code/model/User.scala:30: type mismatch;
[error] found : net.liftweb.mapper.MappedLongIndex[code.model.User]
[error] required: net.liftweb.mapper.MappedForeignKey[Long,?,code.model.User]
[error] object friends extends MappedOneToMany(User, User.id)
[error] ^
What would be the way to go about this?
Regards
If you look at the error message you see that the OneToMany helper needs a foreign key in the "many" end of the relation pointing back to this "one". User.id is the primary key and therefore doesn't fit.
If you think about it what you want is really a ManyToMany-relationship.
That you can create like this:
object User extends User with MetaMegaProtoUser[User] with MappedManyToMany {
...
object friends extends MappedManyToMany(Friends, Friends.friend, Friends.friendee, User)
where you have a join table:
class Friends extends Mapper[Friends] {
object friend extends MappedLongForeignKey(this, User) {
override def dbIndexed_? = true
}
object friendee extends MappedLongForeignKey(this, User) {
override def dbIndexed_? = true
}
def getSingleton = Friends
}
object Friends extends Friends with MetaMapper[Friends]
If you want the friend relation to be reflexive, you'll have to do some further work.
This is an extremely late answer I guess. I would suggest posting to the lift mailing list for extremely fast replies: https://groups.google.com/forum/?fromgroups#!forum/liftweb