Handle response flags correctly, plus some comment changes
This commit is contained in:
Tony Hannan
parent
b03763b1d6
commit
6435bc3cd9
5 changed files with 107 additions and 41 deletions
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@ -1,4 +1,42 @@
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-- | Client interface to MongoDB server(s)
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{- |
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Client interface to MongoDB server(s).
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Simple example:
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>
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> {-# LANGUAGE OverloadedStrings #-}
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>
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> import Database.MongoDB
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>
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> main = do
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> e <- connect (server "127.0.0.1")
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> conn <- either (fail . show) return e
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> e <- runConn run conn
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> either (fail . show) return e
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>
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> run = useDb "baseball" $ do
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> clearTeams
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> insertTeams
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> print' "All Teams" =<< allTeams
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> print' "National League Teams" =<< nationalLeagueTeams
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> print' "New York Teams" =<< newYorkTeams
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>
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> clearTeams = delete (select [] "team")
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>
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> insertTeams = insertMany "team" [
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> ["name" =: "Yankees", "home" =: ["city" =: "New York", "state" =: "NY"], "league" =: "American"],
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> ["name" =: "Mets", "home" =: ["city" =: "New York", "state" =: "NY"], "league" =: "National"],
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> ["name" =: "Phillies", "home" =: ["city" =: "Philadelphia", "state" =: "PA"], "league" =: "National"],
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> ["name" =: "Red Sox", "home" =: ["city" =: "Boston", "state" =: "MA"], "league" =: "American"] ]
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>
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> allTeams = rest =<< find (select [] "team") {sort = ["city" =: 1]}
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>
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> nationalLeagueTeams = rest =<< find (select ["league" =: "National"] "team")
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>
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> newYorkTeams = rest =<< find (select ["home.state" =: "NY"] "team") {project = ["name" =: 1, "league" =: 1]}
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>
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> print' title docs = liftIO $ putStrLn title >> mapM_ print docs
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-}
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module Database.MongoDB (
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module Data.Bson,
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@ -15,7 +15,7 @@ module Database.MongoDB.Internal.Protocol (
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-- ** Request
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Request(..), QueryOption(..),
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-- ** Reply
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Reply(..),
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Reply(..), ResponseFlag(..),
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-- * Authentication
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Username, Password, Nonce, pwHash, pwKey
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) where
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@ -238,12 +238,18 @@ qBits = bitOr . map qBit
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-- | A reply is a message received in response to a 'Request'
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data Reply = Reply {
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rResponseFlag :: Int32, -- ^ 0 = success, non-zero = failure
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rResponseFlags :: [ResponseFlag],
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rCursorId :: CursorId, -- ^ 0 = cursor finished
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rStartingFrom :: Int32,
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rDocuments :: [Document]
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} deriving (Show, Eq)
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data ResponseFlag =
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CursorNotFound -- ^ Set when getMore is called but the cursor id is not valid at the server. Returned with zero results.
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| QueryError -- ^ Server error. Results contains one document containing an "$err" field holding the error message.
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| AwaitCapable -- ^ For backward compatability: Set when the server supports the AwaitData query option. if it doesn't, a replica slave client should sleep a little between getMore's
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deriving (Show, Eq, Enum)
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-- * Binary format
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replyOpcode :: Opcode
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@ -253,13 +259,21 @@ getReply :: Get (ResponseTo, Reply)
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getReply = do
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(opcode, responseTo) <- getHeader
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unless (opcode == replyOpcode) $ fail $ "expected reply opcode (1) but got " ++ show opcode
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rResponseFlag <- getInt32
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rResponseFlags <- rFlags <$> getInt32
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rCursorId <- getInt64
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rStartingFrom <- getInt32
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numDocs <- fromIntegral <$> getInt32
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rDocuments <- replicateM numDocs getDocument
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return (responseTo, Reply{..})
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rFlags :: Int32 -> [ResponseFlag]
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rFlags bits = filter (testBit bits . rBit) [CursorNotFound ..]
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rBit :: ResponseFlag -> Int
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rBit CursorNotFound = 0
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rBit QueryError = 1
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rBit AwaitCapable = 3
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-- * Authentication
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type Username = UString
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@ -1,10 +1,10 @@
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-- | Query and update documents residing on a MongoDB server(s)
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{-# LANGUAGE OverloadedStrings, RecordWildCards, NamedFieldPuns, TupleSections, FlexibleContexts, FlexibleInstances, UndecidableInstances, MultiParamTypeClasses #-}
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{-# LANGUAGE OverloadedStrings, RecordWildCards, NamedFieldPuns, TupleSections, FlexibleContexts, FlexibleInstances, UndecidableInstances, MultiParamTypeClasses, GeneralizedNewtypeDeriving #-}
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module Database.MongoDB.Query (
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-- * Connection
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Failure(..), Conn, Connected, runConn,
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Connected, runConn, Conn, Failure(..),
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-- * Database
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Database, allDatabases, DbConn, useDb, thisDatabase,
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-- ** Authentication
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@ -52,11 +52,22 @@ import Database.MongoDB.Internal.Protocol hiding (Query, send, call)
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import Data.Bson
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import Data.Word
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import Data.Int
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import Data.Maybe (listToMaybe, catMaybes)
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import Data.Maybe (listToMaybe, catMaybes, mapMaybe)
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import Data.UString as U (dropWhile, any, tail)
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import Database.MongoDB.Internal.Util (loop, (<.>), true1) -- plus Applicative instances of ErrorT & ReaderT
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-- * Connection
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-- * Connected
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newtype Connected m a = Connected (ErrorT Failure (ReaderT WriteMode (ReaderT Connection m)) a)
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deriving (Context Connection, Context WriteMode, MonadError Failure, MonadIO, Monad, Applicative, Functor)
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-- ^ Monad with access to a 'Connection' and 'WriteMode' and throws a 'Failure' on connection or server failure
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instance MonadTrans Connected where
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lift = Connected . lift . lift . lift
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runConn :: Connected m a -> Connection -> m (Either Failure a)
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-- ^ Run action with access to connection. Return Left Failure if connection or server fails during execution.
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runConn (Connected action) = runReaderT (runReaderT (runErrorT action) Unsafe)
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-- | A monad with access to a 'Connection' and 'WriteMode' and throws a 'Failure' on connection or server failure
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class (Context Connection m, Context WriteMode m, MonadError Failure m, MonadIO m, Applicative m, Functor m) => Conn m
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@ -72,12 +83,6 @@ data Failure =
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instance Error Failure where strMsg = ServerFailure
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type Connected m = ErrorT Failure (ReaderT WriteMode (ReaderT Connection m))
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runConn :: Connected m a -> Connection -> m (Either Failure a)
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-- ^ Run action with access to connection. Return Left Failure if connection or server fails during execution.
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runConn action = runReaderT (runReaderT (runErrorT action) Unsafe)
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send :: (Conn m) => [Notice] -> m ()
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-- ^ Send notices as a contiguous batch to server with no reply. Raise Failure if connection fails.
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send ns = do
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@ -298,7 +303,7 @@ type Limit = Word32
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-- ^ Maximum number of documents to return, i.e. cursor will close after iterating over this number of documents. 0 means no limit.
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type Order = Document
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-- ^ Fields to sort by. Each one is associated with 1 or -1. Eg. @[x =: 1, y =: (-1)]@ means sort by @x@ ascending then @y@ descending
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-- ^ Fields to sort by. Each one is associated with 1 or -1. Eg. @[x =: 1, y =: -1]@ means sort by @x@ ascending then @y@ descending
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type BatchSize = Word32
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-- ^ The number of document to return in each batch response from the server. 0 means use Mongo default.
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@ -310,10 +315,12 @@ query sel col = Query [] (Select sel col) [] 0 0 [] False 0 []
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batchSizeRemainingLimit :: BatchSize -> Limit -> (Int32, Limit)
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-- ^ Given batchSize and limit return P.qBatchSize and remaining limit
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batchSizeRemainingLimit batchSize limit = if limit == 0
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then (fromIntegral batchSize, 0) -- no limit
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else if 0 < batchSize && batchSize < limit
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then (fromIntegral batchSize, limit - batchSize)
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then (fromIntegral batchSize', 0) -- no limit
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else if 0 < batchSize' && batchSize' < limit
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then (fromIntegral batchSize', limit - batchSize')
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else (- fromIntegral limit, 1)
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where batchSize' = if batchSize == 1 then 2 else batchSize
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-- batchSize 1 is broken because server converts 1 to -1 meaning limit 1
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queryRequest :: Bool -> Query -> Database -> (Request, Limit)
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-- ^ Translate Query to Protocol.Query. If first arg is true then add special $explain attribute.
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@ -334,6 +341,12 @@ runQuery :: (DbConn m) => Bool -> [Notice] -> Query -> m CursorState'
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-- ^ Send query request and return cursor state
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runQuery isExplain ns q = call' ns . queryRequest isExplain q =<< thisDatabase
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call' :: (Conn m) => [Notice] -> (Request, Limit) -> m CursorState'
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-- ^ Send notices and request and return promised cursor state
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call' ns (req, remainingLimit) = do
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promise <- call ns req
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return $ Delayed (fmap (fromReply remainingLimit =<<) promise)
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find :: (DbConn m) => Query -> m Cursor
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-- ^ Fetch documents satisfying query
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find q@Query{selection, batchSize} = do
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@ -397,15 +410,16 @@ data CursorState = CS Limit CursorId [Document]
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fromReply :: Limit -> Reply -> Either Failure CursorState
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-- ^ Convert Reply to CursorState or Failure
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fromReply limit Reply{..} = if rResponseFlag == 0
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then Right (CS limit rCursorId rDocuments)
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else Left . ServerFailure $ "Query failure " ++ show rResponseFlag ++ " " ++ show rDocuments
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call' :: (Conn m) => [Notice] -> (Request, Limit) -> m CursorState'
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-- ^ Send notices and request and return promised cursor state
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call' ns (req, remainingLimit) = do
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promise <- call ns req
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return $ Delayed (fmap (fromReply remainingLimit =<<) promise)
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fromReply limit Reply{..} = case mapMaybe fromResponseFlag rResponseFlags of
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[] -> Right (CS limit rCursorId rDocuments)
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err : _ -> Left err
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where
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fromResponseFlag :: ResponseFlag -> Maybe Failure
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-- ^ If response flag indicate failure then Just Failure, otherwise Nothing
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fromResponseFlag x = case x of
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AwaitCapable -> Nothing
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CursorNotFound -> Just . ServerFailure $ "Cursor " ++ show rCursorId ++ " not found"
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QueryError -> Just . ServerFailure $ "Query failure " ++ show rDocuments
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newCursor :: (Conn m) => Database -> Collection -> BatchSize -> CursorState' -> m Cursor
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-- ^ Create new cursor. If you don't read all results then close it. Cursor will be closed automatically when all results are read from it or when eventually garbage collected.
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@ -432,9 +446,8 @@ next cursor = modifyCursorState' cursor nextState where
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[] -> if cid == 0
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then return (CursorState $ CS 0 0 [], Nothing) -- finished
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else error $ "server returned empty batch but says more results on server"
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nextBatch fcol batch limit cid = let
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(batchSize, remLimit) = batchSizeRemainingLimit batch limit
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in call' [] (GetMore fcol batchSize cid, remLimit)
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nextBatch fcol batch limit cid = call' [] (GetMore fcol batchSize cid, remLimit)
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where (batchSize, remLimit) = batchSizeRemainingLimit batch limit
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nextN :: (Conn m) => Int -> Cursor -> m [Document]
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-- ^ Return next N documents or less if end is reached
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@ -454,17 +467,18 @@ instance (Conn m) => Resource m Cursor where
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-- ** Group
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-- | Groups documents in collection by key then reduces (aggregates) each group
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data Group = Group {
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gColl :: Collection,
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gKey :: GroupKey, -- ^ Fields to group by
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gReduce :: Javascript, -- ^ The reduce function aggregates (reduces) the objects iterated. Typical operations of a reduce function include summing and counting. reduce takes two arguments: the current document being iterated over and the aggregation value.
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gInitial :: Document, -- ^ Initial aggregation value supplied to reduce
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gReduce :: Javascript, -- ^ @(doc, agg) -> ()@. The reduce function reduces (aggregates) the objects iterated. Typical operations of a reduce function include summing and counting. It takes two arguments, the current document being iterated over and the aggregation value, and updates the aggregate value.
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gInitial :: Document, -- ^ @agg@. Initial aggregation value supplied to reduce
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gCond :: Selector, -- ^ Condition that must be true for a row to be considered. [] means always true.
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gFinalize :: Maybe Javascript -- ^ An optional function to be run on each item in the result set just before the item is returned. Can either modify the item (e.g., add an average field given a count and a total) or return a replacement object (returning a new object with just _id and average fields).
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gFinalize :: Maybe Javascript -- ^ @agg -> () | result@. An optional function to be run on each item in the result set just before the item is returned. Can either modify the item (e.g., add an average field given a count and a total) or return a replacement object (returning a new object with just _id and average fields).
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} deriving (Show, Eq)
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data GroupKey = Key [Label] | KeyF Javascript deriving (Show, Eq)
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-- ^ Fields to group by, or function returning a "key object" to be used as the grouping key. Use this instead of key to specify a key that is not an existing member of the object (or, to access embedded members).
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-- ^ Fields to group by, or function (@doc -> key@) returning a "key object" to be used as the grouping key. Use KeyF instead of Key to specify a key that is not an existing member of the object (or, to access embedded members).
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groupDocument :: Group -> Document
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-- ^ Translate Group data into expected document form
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@ -482,12 +496,12 @@ group g = at "retval" <$> runCommand ["group" =: groupDocument g]
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-- ** MapReduce
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-- | Maps every document in collection to a (key, value) pair, then for each unique key reduces all its associated values to a result. Therefore, the final output is a list of (key, result) pairs, where every key is unique. This is the basic description. There are additional nuances that may be used. See <http://www.mongodb.org/display/DOCS/MapReduce> for details.
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-- | Maps every document in collection to a list of (key, value) pairs, then for each unique key reduces all its associated values from all lists to a single result. There are additional parameters that may be set to tweak this basic operation.
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data MapReduce = MapReduce {
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rColl :: Collection,
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rMap :: MapFun,
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rReduce :: ReduceFun,
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rSelect :: Selector, -- ^ Default is []
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rSelect :: Selector, -- ^ Operate on only those documents selected. Default is [] meaning all documents.
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rSort :: Order, -- ^ Default is [] meaning no sort
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rLimit :: Limit, -- ^ Default is 0 meaning no limit
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rOut :: Maybe Collection, -- ^ Output to given permanent collection, otherwise output to a new temporary collection whose name is returned.
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@ -498,10 +512,10 @@ data MapReduce = MapReduce {
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} deriving (Show, Eq)
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type MapFun = Javascript
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-- ^ @() -> void@. The map function references the variable this to inspect the current object under consideration. A map function must call @emit(key,value)@ at least once, but may be invoked any number of times, as may be appropriate.
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-- ^ @() -> void@. The map function references the variable @this@ to inspect the current object under consideration. The function must call @emit(key,value)@ at least once, but may be invoked any number of times, as may be appropriate.
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type ReduceFun = Javascript
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-- ^ @(key, value_array) -> value@. The reduce function receives a key and an array of values. To use, reduce the received values, and return a result. The MapReduce engine may invoke reduce functions iteratively; thus, these functions must be idempotent. That is, the following must hold for your reduce function: @for all k, vals : reduce(k, [reduce(k,vals)]) == reduce(k,vals)@. If you need to perform an operation only once, use a finalize function. The output of emit (the 2nd param) and reduce should be the same format to make iterative reduce possible.
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-- ^ @(key, value_array) -> value@. The reduce function receives a key and an array of values and returns an aggregate result value. The MapReduce engine may invoke reduce functions iteratively; thus, these functions must be idempotent. That is, the following must hold for your reduce function: @for all k, vals : reduce(k, [reduce(k,vals)]) == reduce(k,vals)@. If you need to perform an operation only once, use a finalize function. The output of emit (the 2nd param) and reduce should be the same format to make iterative reduce possible.
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type FinalizeFun = Javascript
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-- ^ @(key, value) -> final_value@. A finalize function may be run after reduction. Such a function is optional and is not necessary for many map/reduce cases. The finalize function takes a key and a value, and returns a finalized value.
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@ -1,5 +1,5 @@
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Name: mongoDB
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Version: 0.6
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Version: 0.6.1
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License: OtherLicense
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License-file: LICENSE
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Maintainer: Tony Hannan <tony@10gen.com>
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@ -55,12 +55,12 @@ Open up a connection to your DB instance, using the standard port:
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or for a non-standard port
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> Right con <- connect $ server "127.0.0.1" (PortNumber 666)
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> Right con <- connect $ Server "127.0.0.1" (PortNumber 666)
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*connect* returns Left IOError if connection fails. We are assuming above
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it won't fail. If it does you will get a pattern match error.
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Task and Db monad
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Connected monad
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-------------------
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The current connection is held in a Connected monad, and the current database
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