@@ -1,18 +1,14 @@
1−{-# LANGUAGE DeriveDataTypeable #-}
2−{-# LANGUAGE NamedFieldPuns #-}
3−{-# LANGUAGE OverloadedStrings #-}
4−{-# LANGUAGE PatternGuards #-}
5−{-# LANGUAGE RecordWildCards #-}
6−{-# LANGUAGE ViewPatterns #-}
7−
1+{-# LANGUAGE BangPatterns, DeriveDataTypeable, OverloadedStrings #-}
2+{-# LANGUAGE DoAndIfThenElse, RecordWildCards, NamedFieldPuns #-}
83------------------------------------------------------------------------------
94-- |
105-- Module: Database.PostgreSQL.Simple
116-- Copyright: (c) 2011 MailRank, Inc.
12−-- (c) 2011-2012 Leon P Smith
7+-- (c) 2011 Leon P Smith
138-- License: BSD3
149-- Maintainer: Leon P Smith <leon@melding-monads.com>
1510-- Stability: experimental
11+-- Portability: portable
1612--
1713-- A mid-level client library for the PostgreSQL database, aimed at ease of
1814-- use and high performance.
@@ -42,9 +38,6 @@ module Database.PostgreSQL.Simple
4238 -- ** Modifying multiple rows at once
4339 -- $many
4440
45− -- ** @RETURNING@: modifications that return results
46− -- $returning
47−
4841 -- * Extracting results
4942 -- $result
5043
@@ -55,35 +48,26 @@ module Database.PostgreSQL.Simple
5548 -- $types
5649
5750 -- * Types
58− Connection
51+ Base.ConnectInfo(..)
52+ , Connection
5953 , Query
60− , ToRow
61− , FromRow
6254 , In(..)
6355 , Binary(..)
6456 , Only(..)
65− , (:.)(..)
6657 -- ** Exceptions
67− , SomePostgreSqlException(..)
6858 , SqlError(..)
69− , PQ.ExecStatus(..)
70− , FormatError(..)
71− , QueryError(..)
72− , ResultError(..)
59+ , FormatError(fmtMessage, fmtQuery, fmtParams)
60+ , QueryError(qeMessage, qeQuery)
61+ , ResultError(errSQLType, errHaskellType, errMessage)
7362 -- * Connection management
74− , Base.connectPostgreSQL
75− , Base.close
7663 , Base.connect
77− , Base.withConnect
78− , Base.ConnectInfo(..)
79− , Base.defaultConnectInfo
64+ , Base.connectPostgreSQL
8065 , Base.postgreSQLConnectionString
66+ , Base.defaultConnectInfo
67+ , Base.close
8168 -- * Queries that return results
8269 , query
8370 , query_
84− -- ** Queries taking parser as argument
85− , queryWith
86− , queryWith_
8771 -- * Queries that stream results
8872 , FoldOptions(..)
8973 , FetchQuantity(..)
@@ -94,15 +78,6 @@ module Database.PostgreSQL.Simple
9478 , foldWithOptions_
9579 , forEach
9680 , forEach_
97− , returning
98− -- ** Queries that stream results taking a parser as an argument
99− , foldWith
100− , foldWithOptionsAndParser
101− , foldWith_
102− , foldWithOptionsAndParser_
103− , forEachWith
104− , forEachWith_
105− , returningWith
10681 -- * Statements that do not return results
10782 , execute
10883 , execute_
@@ -110,9 +85,13 @@ module Database.PostgreSQL.Simple
11085-- , Base.insertID
11186 -- * Transaction handling
11287 , withTransaction
113− , withSavepoint
88+ , TransactionMode(..)
89+ , IsolationLevel(..)
90+ , ReadWriteMode(..)
91+ , withTransactionMode
11492-- , Base.autocommit
11593 , begin
94+ , beginMode
11695 , commit
11796 , rollback
11897 -- * Helper functions
@@ -120,27 +99,50 @@ module Database.PostgreSQL.Simple
12099 , formatQuery
121100 ) where
122101
123−import Data.ByteString.Builder (Builder, byteString, char8)
124−import Control.Applicative ((<$>))
125−import Control.Exception as E
126−import Data.ByteString (ByteString)
127−import Data.Int (Int64)
128−import Data.List (intersperse)
129−import Data.Monoid (mconcat)
130−import Database.PostgreSQL.Simple.Compat ((<>), toByteString)
131−import Database.PostgreSQL.Simple.Cursor
132−import Database.PostgreSQL.Simple.FromField (ResultError(..))
133−import Database.PostgreSQL.Simple.FromRow (FromRow(..))
134−import Database.PostgreSQL.Simple.ToField (Action(..))
135−import Database.PostgreSQL.Simple.ToRow (ToRow(..))
136−import Database.PostgreSQL.Simple.Types
137− ( Binary(..), In(..), Only(..), Query(..), (:.)(..) )
138−import Database.PostgreSQL.Simple.Internal as Base
139−import Database.PostgreSQL.Simple.Internal.PQResultUtils
140−import Database.PostgreSQL.Simple.Transaction
102+import Blaze.ByteString.Builder (Builder, fromByteString, toByteString)
103+import Blaze.ByteString.Builder.Char8 (fromChar)
104+import Control.Applicative ((<$>), pure)
105+import Control.Concurrent.MVar
106+import Control.Exception (Exception, bracket, onException, throw, throwIO, finally)
107+import Control.Monad (foldM)
108+import Control.Monad.Fix (fix)
109+import Data.ByteString (ByteString)
110+import Data.Char(ord)
111+import Data.Int (Int64)
112+import qualified Data.IntMap as IntMap
113+import Data.List (intersperse)
114+import Data.Monoid (mappend, mconcat)
115+import Data.Typeable (Typeable)
116+import Database.PostgreSQL.Simple.BuiltinTypes (oid2builtin, builtin2typname)
117+import Database.PostgreSQL.Simple.Param (Action(..), inQuotes)
118+import Database.PostgreSQL.Simple.QueryParams (QueryParams(..))
119+import Database.PostgreSQL.Simple.Result (ResultError(..))
120+import Database.PostgreSQL.Simple.QueryResults (QueryResults(..))
121+import Database.PostgreSQL.Simple.Types (Binary(..), In(..), Only(..), Query(..))
122+import Database.PostgreSQL.Simple.Internal as Base
141123import qualified Database.PostgreSQL.LibPQ as PQ
124+import Text.Regex.PCRE.Light (compile, caseless, match)
142125import qualified Data.ByteString.Char8 as B
143126
127+-- | Exception thrown if a 'Query' could not be formatted correctly.
128+-- This may occur if the number of \'@?@\' characters in the query
129+-- string does not match the number of parameters provided.
130+data FormatError = FormatError {
131+ fmtMessage :: String
132+ , fmtQuery :: Query
133+ , fmtParams :: [ByteString]
134+ } deriving (Eq, Show, Typeable)
135+
136+instance Exception FormatError
137+
138+-- | Exception thrown if 'query' is used to perform an @INSERT@-like
139+-- operation, or 'execute' is used to perform a @SELECT@-like operation.
140+data QueryError = QueryError {
141+ qeMessage :: String
142+ , qeQuery :: Query
143+ } deriving (Eq, Show, Typeable)
144+
145+instance Exception QueryError
144146
145147-- | Format a query string.
146148--
@@ -152,11 +154,11 @@ import qualified Data.ByteString.Char8 as B
152154--
153155-- Throws 'FormatError' if the query string could not be formatted
154156-- correctly.
155−formatQuery :: ToRow q => Connection -> Query -> q -> IO ByteString
157+formatQuery :: QueryParams q => Connection -> Query -> q -> IO ByteString
156158formatQuery conn q@(Query template) qs
157159 | null xs && '?' `B.notElem` template = return template
158160 | otherwise = toByteString <$> buildQuery conn q template xs
159− where xs = toRow qs
161+ where xs = renderParams qs
160162
161163-- | Format a query string with a variable number of rows.
162164--
@@ -171,208 +173,105 @@ formatQuery conn q@(Query template) qs
171173--
172174-- Throws 'FormatError' if the query string could not be formatted
173175-- correctly.
174−formatMany :: (ToRow q) => Connection -> Query -> [q] -> IO ByteString
176+formatMany :: (QueryParams q) => Connection -> Query -> [q] -> IO ByteString
175177formatMany _ q [] = fmtError "no rows supplied" q []
176178formatMany conn q@(Query template) qs = do
177− case parseTemplate template of
178− Just (before, qbits, after) -> do
179− bs <- mapM (buildQuery conn q qbits . toRow) qs
180− return . toByteString . mconcat $ byteString before :
181− intersperse (char8 ',') bs ++
182− [byteString after]
183− Nothing -> fmtError "syntax error in multi-row template" q []
184−
185−-- Split the input string into three pieces, @before@, @qbits@, and @after@,
186−-- following this grammar:
187−--
188−-- start: ^ before qbits after $
189−-- before: ([^?]* [^?\w])? 'VALUES' \s*
190−-- qbits: '(' \s* '?' \s* (',' \s* '?' \s*)* ')'
191−-- after: [^?]*
192−--
193−-- \s: [ \t\n\r\f]
194−-- \w: [A-Z] | [a-z] | [\x80-\xFF] | '_' | '$' | [0-9]
195−--
196−-- This would be much more concise with some sort of regex engine.
197−-- 'formatMany' used to use pcre-light instead of this hand-written parser,
198−-- but pcre is a hassle to install on Windows.
199−parseTemplate :: ByteString -> Maybe (ByteString, ByteString, ByteString)
200−parseTemplate template =
201− -- Convert input string to uppercase, to facilitate searching.
202− search $ B.map toUpper_ascii template
179+ case match re template [] of
180+ Just [_,before,qbits,after] -> do
181+ bs <- mapM (buildQuery conn q qbits . renderParams) qs
182+ return . toByteString . mconcat $ fromByteString before :
183+ intersperse (fromChar ',') bs ++
184+ [fromByteString after]
185+ _ -> error "foo"
203186 where
204− -- Search for the next occurrence of "VALUES"
205− search bs =
206− case B.breakSubstring "VALUES" bs of
207− (x, y)
208− -- If "VALUES" is not present in the string, or any '?' characters
209− -- were encountered prior to it, fail.
210− | B.null y || ('?' `B.elem` x)
211− -> Nothing
212−
213− -- If "VALUES" is preceded by an identifier character (a.k.a. \w),
214− -- try the next occurrence.
215− | not (B.null x) && isIdent (B.last x)
216− -> search $ B.drop 6 y
217−
218− -- Otherwise, we have a legitimate "VALUES" token.
219− | otherwise
220− -> parseQueryBits $ skipSpace $ B.drop 6 y
221−
222− -- Parse '(' \s* '?' \s* . If this doesn't match
223− -- (and we don't consume a '?'), look for another "VALUES".
224− --
225− -- qb points to the open paren (if present), meaning it points to the
226− -- beginning of the "qbits" production described above. This is why we
227− -- pass it down to finishQueryBits.
228− parseQueryBits qb
229− | Just ('(', skipSpace -> bs1) <- B.uncons qb
230− , Just ('?', skipSpace -> bs2) <- B.uncons bs1
231− = finishQueryBits qb bs2
232− | otherwise
233− = search qb
234−
235− -- Parse (',' \s* '?' \s*)* ')' [^?]* .
236− --
237− -- Since we've already consumed at least one '?', there's no turning back.
238− -- The parse has to succeed here, or the whole thing fails
239− -- (because we don't allow '?' to appear outside of the VALUES list).
240− finishQueryBits qb bs0
241− | Just (')', bs1) <- B.uncons bs0
242− = if '?' `B.elem` bs1
243− then Nothing
244− else Just $ slice3 template qb bs1
245− | Just (',', skipSpace -> bs1) <- B.uncons bs0
246− , Just ('?', skipSpace -> bs2) <- B.uncons bs1
247− = finishQueryBits qb bs2
248− | otherwise
249− = Nothing
250−
251− -- Slice a string into three pieces, given the start offset of the second
252− -- and third pieces. Each "offset" is actually a tail of the uppercase
253− -- version of the template string. Its length is used to infer the offset.
254− --
255− -- It is important to note that we only slice the original template.
256− -- We don't want our all-caps trick messing up the actual query string.
257− slice3 source p1 p2 =
258− (s1, s2, source'')
259− where
260− (s1, source') = B.splitAt (B.length source - B.length p1) source
261− (s2, source'') = B.splitAt (B.length p1 - B.length p2) source'
262−
263− toUpper_ascii c | c >= 'a' && c <= 'z' = toEnum (fromEnum c - 32)
264− | otherwise = c
265−
266− -- Based on the definition of {ident_cont} in src/backend/parser/scan.l
267− -- in the PostgreSQL source. No need to check [a-z], since we converted
268− -- the whole string to uppercase.
269− isIdent c = (c >= '0' && c <= '9')
270− || (c >= 'A' && c <= 'Z')
271− || (c >= '\x80' && c <= '\xFF')
272− || c == '_'
273− || c == '$'
274−
275− -- Based on {space} in scan.l
276− isSpace_ascii c = (c == ' ') || (c >= '\t' && c <= '\r')
277−
278− skipSpace = B.dropWhile isSpace_ascii
187+ re = compile "^([^?]+\\bvalues\\s*)\
188+ \(\\(\\s*[?](?:\\s*,\\s*[?])*\\s*\\))\
189+ \([^?]*)$"
190+ [caseless]
279191
192+escapeStringConn conn s = withConnection conn $ \c -> do
193+ PQ.escapeStringConn c s
280194
281195buildQuery :: Connection -> Query -> ByteString -> [Action] -> IO Builder
282−buildQuery conn q template xs =
283− zipParams (split template) <$> mapM (buildAction conn q xs) xs
284− where split s =
285− -- This part escapes double '??'s to make literal '?'s possible
286− -- in PostgreSQL queries using the JSON operators: @?@, @?|@ and @?&@
287− let (h,t) = breakOnSingleQuestionMark s
288− in byteString h
289− : if B.null t
290− then []
291− else split (B.tail t)
292− zipParams (t:ts) (p:ps) = t <> p <> zipParams ts ps
196+buildQuery conn q template xs = zipParams (split template) <$> mapM sub xs
197+ where quote = inQuotes . fromByteString . maybe undefined id
198+ sub (Plain b) = pure b
199+ sub (Escape s) = quote <$> escapeStringConn conn s
200+ sub (Many ys) = mconcat <$> mapM sub ys
201+ split s = fromByteString h : if B.null t then [] else split (B.tail t)
202+ where (h,t) = B.break (=='?') s
203+ zipParams (t:ts) (p:ps) = t `mappend` p `mappend` zipParams ts ps
293204 zipParams [t] [] = t
294− zipParams _ _ = fmtError (show countSingleQs ++
295− " single '?' characters, but " ++
205+ zipParams _ _ = fmtError (show (B.count '?' template) ++
206+ " '?' characters, but " ++
296207 show (length xs) ++ " parameters") q xs
297− countSingleQs = go 0 template
298− where go i "" = (i :: Int)
299− go i bs = case qms of
300− ("?","?") -> go i nextQMBS
301− ("?",_) -> go (i+1) nextQMBS
302− _ -> i
303− where qms = B.splitAt 1 qmBS
304− (qmBS,nextQMBS) = B.splitAt 2 qmBS'
305− qmBS' = B.dropWhile (/= '?') bs
306208
307209-- | Execute an @INSERT@, @UPDATE@, or other SQL query that is not
308210-- expected to return results.
309211--
310212-- Returns the number of rows affected.
311213--
312−-- Throws 'FormatError' if the query could not be formatted correctly, or
313−-- a 'SqlError' exception if the backend returns an error.
314−execute :: (ToRow q) => Connection -> Query -> q -> IO Int64
214+-- Throws 'FormatError' if the query could not be formatted correctly.
215+execute :: (QueryParams q) => Connection -> Query -> q -> IO Int64
315216execute conn template qs = do
316217 result <- exec conn =<< formatQuery conn template qs
317218 finishExecute conn template result
318219
220+-- | A version of 'execute' that does not perform query substitution.
221+execute_ :: Connection -> Query -> IO Int64
222+execute_ conn q@(Query stmt) = do
223+ result <- exec conn stmt
224+ finishExecute conn q result
225+
319226-- | Execute a multi-row @INSERT@, @UPDATE@, or other SQL query that is not
320227-- expected to return results.
321228--
322−-- Returns the number of rows affected. If the list of parameters is empty,
323−-- this function will simply return 0 without issuing the query to the backend.
324−-- If this is not desired, consider using the 'Values' constructor instead.
325−--
326−-- Throws 'FormatError' if the query could not be formatted correctly, or
327−-- a 'SqlError' exception if the backend returns an error.
328−--
329−-- For example, here's a command that inserts two rows into a table
330−-- with two columns:
331−--
332−-- @
333−-- executeMany c [sql|
334−-- INSERT INTO sometable VALUES (?,?)
335−-- |] [(1, \"hello\"),(2, \"world\")]
336−-- @
337−--
338−-- Here's an canonical example of a multi-row update command:
229+-- Returns the number of rows affected.
339230--
340−-- @
341−-- executeMany c [sql|
342−-- UPDATE sometable
343−-- SET y = upd.y
344−-- FROM (VALUES (?,?)) as upd(x,y)
345−-- WHERE sometable.x = upd.x
346−-- |] [(1, \"hello\"),(2, \"world\")]
347−-- @
348−
349−executeMany :: (ToRow q) => Connection -> Query -> [q] -> IO Int64
231+-- Throws 'FormatError' if the query could not be formatted correctly.
232+executeMany :: (QueryParams q) => Connection -> Query -> [q] -> IO Int64
350233executeMany _ _ [] = return 0
351234executeMany conn q qs = do
352235 result <- exec conn =<< formatMany conn q qs
353236 finishExecute conn q result
354237
355−-- | Execute @INSERT ... RETURNING@, @UPDATE ... RETURNING@, or other SQL
356−-- query that accepts multi-row input and is expected to return results.
357−-- Note that it is possible to write
358−-- @'query' conn "INSERT ... RETURNING ..." ...@
359−-- in cases where you are only inserting a single row, and do not need
360−-- functionality analogous to 'executeMany'.
361−--
362−-- If the list of parameters is empty, this function will simply return @[]@
363−-- without issuing the query to the backend. If this is not desired,
364−-- consider using the 'Values' constructor instead.
365−--
366−-- Throws 'FormatError' if the query could not be formatted correctly.
367−returning :: (ToRow q, FromRow r) => Connection -> Query -> [q] -> IO [r]
368−returning = returningWith fromRow
238+finishExecute :: Connection -> Query -> PQ.Result -> IO Int64
239+finishExecute conn q result = do
240+ status <- PQ.resultStatus result
241+ case status of
242+ PQ.CommandOk -> do
243+ ncols <- PQ.nfields result
244+ if ncols /= 0
245+ then throwIO $ QueryError ("execute resulted in " ++ show ncols ++
246+ "-column result") q
247+ else do
248+ nstr <- PQ.cmdTuples result
249+ return $ case nstr of
250+ Nothing -> 0 -- is this appropriate?
251+ Just str -> toInteger str
252+ PQ.TuplesOk -> do
253+ ncols <- PQ.nfields result
254+ throwIO $ QueryError ("execute resulted in " ++ show ncols ++
255+ "-column result") q
256+ PQ.CopyIn -> fail "FIXME: postgresql-simple does not currently support COPY IN"
257+ PQ.CopyOut -> fail "FIXME: postgresql-simple does not currently support COPY OUT"
258+ _ -> do
259+ errormsg <- maybe "" id <$> PQ.resultErrorMessage result
260+ statusmsg <- PQ.resStatus status
261+ state <- maybe "" id <$> PQ.resultErrorField result PQ.DiagSqlstate
262+ throwIO $ SqlError { sqlState = state
263+ , sqlNativeError = fromEnum status
264+ , sqlErrorMsg = B.concat [ "execute: ", statusmsg
265+ , ": ", errormsg ]}
266+ where
267+ toInteger str = B.foldl' delta 0 str
268+ where
269+ delta acc c =
270+ if '0' <= c && c <= '9'
271+ then 10 * acc + fromIntegral (ord c - ord '0')
272+ else error ("finishExecute: not an int: " ++ B.unpack str)
273+
369274
370−-- | A version of 'returning' taking parser as argument
371−returningWith :: (ToRow q) => RowParser r -> Connection -> Query -> [q] -> IO [r]
372−returningWith _ _ _ [] = return []
373−returningWith parser conn q qs = do
374− result <- exec conn =<< formatMany conn q qs
375− finishQueryWith parser conn q result
376275
377276-- | Perform a @SELECT@ or other SQL query that is expected to return
378277-- results. All results are retrieved and converted before this
@@ -389,27 +288,17 @@ returningWith parser conn q qs = do
389288-- using 'execute' instead of 'query').
390289--
391290-- * 'ResultError': result conversion failed.
392−--
393−-- * 'SqlError': the postgresql backend returned an error, e.g.
394−-- a syntax or type error, or an incorrect table or column name.
395−query :: (ToRow q, FromRow r) => Connection -> Query -> q -> IO [r]
396−query = queryWith fromRow
397−
398−-- | A version of 'query' that does not perform query substitution.
399−query_ :: (FromRow r) => Connection -> Query -> IO [r]
400−query_ = queryWith_ fromRow
401−
402−-- | A version of 'query' taking parser as argument
403−queryWith :: ToRow q => RowParser r -> Connection -> Query -> q -> IO [r]
404−queryWith parser conn template qs = do
291+query :: (QueryParams q, QueryResults r)
292+ => Connection -> Query -> q -> IO [r]
293+query conn template qs = do
405294 result <- exec conn =<< formatQuery conn template qs
406− finishQueryWith parser conn template result
295+ finishQuery conn template result
407296
408−-- | A version of 'query_' taking parser as argument
409−queryWith_ :: RowParser r -> Connection -> Query -> IO [r]
410−queryWith_ parser conn q@(Query que) = do
297+-- | A version of 'query' that does not perform query substitution.
298+query_ :: (QueryResults r) => Connection -> Query -> IO [r]
299+query_ conn q@(Query que) = do
411300 result <- exec conn que
412− finishQueryWith parser conn q result
301+ finishQuery conn q result
413302
414303-- | Perform a @SELECT@ or other SQL query that is expected to return
415304-- results. Results are streamed incrementally from the server, and
@@ -421,12 +310,6 @@ queryWith_ parser conn q@(Query que) = do
421310-- This fold is /not/ strict. The stream consumer is responsible for
422311-- forcing the evaluation of its result to avoid space leaks.
423312--
424−-- This is implemented using a database cursor. As such, this requires
425−-- a transaction. This function will detect whether or not there is a
426−-- transaction in progress, and will create a 'ReadCommitted' 'ReadOnly'
427−-- transaction if needed. The cursor is given a unique temporary name,
428−-- so the consumer may itself call fold.
429−--
430313-- Exceptions that may be thrown:
431314--
432315-- * 'FormatError': the query string could not be formatted correctly.
@@ -435,10 +318,8 @@ queryWith_ parser conn q@(Query que) = do
435318-- using 'execute' instead of 'query').
436319--
437320-- * 'ResultError': result conversion failed.
438−--
439−-- * 'SqlError': the postgresql backend returned an error, e.g.
440−-- a syntax or type error, or an incorrect table or column name.
441−fold :: ( FromRow row, ToRow params )
321+
322+fold :: ( QueryResults row, QueryParams params )
442323 => Connection
443324 -> Query
444325 -> params
@@ -447,20 +328,6 @@ fold :: ( FromRow row, ToRow params )
447328 -> IO a
448329fold = foldWithOptions defaultFoldOptions
449330
450−-- | A version of 'fold' taking a parser as an argument
451−foldWith :: ( ToRow params )
452− => RowParser row
453− -> Connection
454− -> Query
455− -> params
456− -> a
457− -> (a -> row -> IO a)
458− -> IO a
459−foldWith = foldWithOptionsAndParser defaultFoldOptions
460−
461−-- | Number of rows to fetch at a time. 'Automatic' currently defaults
462−-- to 256 rows, although it might be nice to make this more intelligent
463−-- based on e.g. the average size of the rows.
464331data FetchQuantity
465332 = Automatic
466333 | Fixed !Int
@@ -471,20 +338,12 @@ data FoldOptions
471338 transactionMode :: !TransactionMode
472339 }
473340
474−-- | defaults to 'Automatic', and 'TransactionMode' 'ReadCommitted' 'ReadOnly'
475−defaultFoldOptions :: FoldOptions
476−defaultFoldOptions = FoldOptions {
341+defaultFoldOptions = FoldOptions {
477342 fetchQuantity = Automatic,
478343 transactionMode = TransactionMode ReadCommitted ReadOnly
479344 }
480345
481−-- | The same as 'fold', but this provides a bit more control over
482−-- lower-level details. Currently, the number of rows fetched per
483−-- round-trip to the server and the transaction mode may be adjusted
484−-- accordingly. If the connection is already in a transaction,
485−-- then the existing transaction is used and thus the 'transactionMode'
486−-- option is ignored.
487−foldWithOptions :: ( FromRow row, ToRow params )
346+foldWithOptions :: ( QueryResults row, QueryParams params )
488347 => FoldOptions
489348 -> Connection
490349 -> Query
@@ -492,24 +351,12 @@ foldWithOptions :: ( FromRow row, ToRow params )
492351 -> a
493352 -> (a -> row -> IO a)
494353 -> IO a
495−foldWithOptions opts = foldWithOptionsAndParser opts fromRow
496−
497−-- | A version of 'foldWithOptions' taking a parser as an argument
498−foldWithOptionsAndParser :: (ToRow params)
499− => FoldOptions
500− -> RowParser row
501− -> Connection
502− -> Query
503− -> params
504− -> a
505− -> (a -> row -> IO a)
506− -> IO a
507−foldWithOptionsAndParser opts parser conn template qs a f = do
354+foldWithOptions opts conn template qs a f = do
508355 q <- formatQuery conn template qs
509− doFold opts parser conn template (Query q) a f
356+ doFold opts conn template (Query q) a f
510357
511358-- | A version of 'fold' that does not perform query substitution.
512−fold_ :: (FromRow r) =>
359+fold_ :: (QueryResults r) =>
513360 Connection
514361 -> Query -- ^ Query.
515362 -> a -- ^ Initial state for result consumer.
@@ -517,43 +364,26 @@ fold_ :: (FromRow r) =>
517364 -> IO a
518365fold_ = foldWithOptions_ defaultFoldOptions
519366
520−-- | A version of 'fold_' taking a parser as an argument
521−foldWith_ :: RowParser r
522− -> Connection
523− -> Query
524− -> a
525− -> (a -> r -> IO a)
526− -> IO a
527−foldWith_ = foldWithOptionsAndParser_ defaultFoldOptions
528367
529−foldWithOptions_ :: (FromRow r) =>
368+foldWithOptions_ :: (QueryResults r) =>
530369 FoldOptions
531370 -> Connection
532371 -> Query -- ^ Query.
533372 -> a -- ^ Initial state for result consumer.
534373 -> (a -> r -> IO a) -- ^ Result consumer.
535374 -> IO a
536−foldWithOptions_ opts conn query' a f = doFold opts fromRow conn query' query' a f
537−
538−-- | A version of 'foldWithOptions_' taking a parser as an argument
539−foldWithOptionsAndParser_ :: FoldOptions
540− -> RowParser r
541− -> Connection
542− -> Query -- ^ Query.
543− -> a -- ^ Initial state for result consumer.
544− -> (a -> r -> IO a) -- ^ Result consumer.
545− -> IO a
546−foldWithOptionsAndParser_ opts parser conn query' a f = doFold opts parser conn query' query' a f
547−
548−doFold :: FoldOptions
549− -> RowParser row
375+foldWithOptions_ opts conn query a f = doFold opts conn query query a f
376+
377+
378+doFold :: ( QueryResults row )
379+ => FoldOptions
550380 -> Connection
551381 -> Query
552382 -> Query
553383 -> a
554384 -> (a -> row -> IO a)
555385 -> IO a
556−doFold FoldOptions{..} parser conn _template q a0 f = do
386+doFold FoldOptions{..} conn _template q a f = do
557387 stat <- withConnection conn PQ.transactionStatus
558388 case stat of
559389 PQ.TransIdle -> withTransactionMode transactionMode conn go
@@ -571,17 +401,11 @@ doFold FoldOptions{..} parser conn _template q a0 f = do
571401 PQ.TransUnknown -> fail "foldWithOpts FIXME: PQ.TransUnknown"
572402 -- Not sure what this means.
573403 where
574− declare =
575− declareCursor conn q
576− fetch cursor a =
577− foldForwardWithParser cursor parser chunkSize f a
578−
579− go = bracket declare closeCursor $ \cursor ->
580− let loop a = fetch cursor a >>=
581− \r -> case r of
582− Left x -> return x
583− Right x -> loop x
584− in loop a0
404+ go = do
405+ -- FIXME: what about name clashes with already-declared cursors?
406+ _ <- execute_ conn ("DECLARE fold NO SCROLL CURSOR FOR "
407+ `mappend` q)
408+ loop a `finally` execute_ conn "CLOSE fold"
585409
586410-- FIXME: choose the Automatic chunkSize more intelligently
587411-- One possibility is to use the type of the results, although this
@@ -592,45 +416,151 @@ doFold FoldOptions{..} parser conn _template q a0 f = do
592416 chunkSize = case fetchQuantity of
593417 Automatic -> 256
594418 Fixed n -> n
419+ loop a = do
420+ rs <- query conn "FETCH FORWARD ? FROM fold" (Only chunkSize)
421+ if null rs then return a else foldM f a rs >>= loop
595422
596423-- | A version of 'fold' that does not transform a state value.
597−forEach :: (ToRow q, FromRow r) =>
424+forEach :: (QueryParams q, QueryResults r) =>
598425 Connection
599426 -> Query -- ^ Query template.
600427 -> q -- ^ Query parameters.
601428 -> (r -> IO ()) -- ^ Result consumer.
602429 -> IO ()
603−forEach = forEachWith fromRow
430+forEach conn template qs = fold conn template qs () . const
604431{-# INLINE forEach #-}
605432
606−-- | A version of 'forEach' taking a parser as an argument
607−forEachWith :: ( ToRow q )
608− => RowParser r
609− -> Connection
610− -> Query
611− -> q
612− -> (r -> IO ())
613− -> IO ()
614−forEachWith parser conn template qs = foldWith parser conn template qs () . const
615−{-# INLINE forEachWith #-}
616−
617433-- | A version of 'forEach' that does not perform query substitution.
618−forEach_ :: (FromRow r) =>
434+forEach_ :: (QueryResults r) =>
619435 Connection
620436 -> Query -- ^ Query template.
621437 -> (r -> IO ()) -- ^ Result consumer.
622438 -> IO ()
623−forEach_ = forEachWith_ fromRow
439+forEach_ conn template = fold_ conn template () . const
624440{-# INLINE forEach_ #-}
625441
626−forEachWith_ :: RowParser r
627− -> Connection
628− -> Query
629− -> (r -> IO ())
630− -> IO ()
631−forEachWith_ parser conn template = foldWith_ parser conn template () . const
632−{-# INLINE forEachWith_ #-}
633−
442+forM' :: (Ord n, Num n) => n -> n -> (n -> IO a) -> IO [a]
443+forM' lo hi m = loop hi []
444+ where
445+ loop !n !as
446+ | n < lo = return as
447+ | otherwise = do
448+ a <- m n
449+ loop (n-1) (a:as)
450+
451+finishQuery :: (QueryResults r) => Connection -> Query -> PQ.Result -> IO [r]
452+finishQuery conn q result = do
453+ status <- PQ.resultStatus result
454+ case status of
455+ PQ.CommandOk -> do
456+ throwIO $ QueryError "query resulted in a command response" q
457+ PQ.TuplesOk -> do
458+ ncols <- PQ.nfields result
459+ fields <- forM' 0 (ncols-1) $ \column -> do
460+ type_oid <- PQ.ftype result column
461+ typename <- getTypename conn type_oid
462+ return Field{..}
463+ nrows <- PQ.ntuples result
464+ forM' 0 (nrows-1) $ \row -> do
465+ values <- forM' 0 (ncols-1) (\col -> PQ.getvalue result row col)
466+ case convertResults fields values of
467+ Left err -> throwIO err
468+ Right a -> return a
469+ PQ.CopyIn -> fail "FIXME: postgresql-simple does not currently support COPY IN"
470+ PQ.CopyOut -> fail "FIXME: postgresql-simple does not currently support COPY OUT"
471+ _ -> do
472+ errormsg <- maybe "" id <$> PQ.resultErrorMessage result
473+ statusmsg <- PQ.resStatus status
474+ state <- maybe "" id <$> PQ.resultErrorField result PQ.DiagSqlstate
475+ throwIO $ SqlError { sqlState = state
476+ , sqlNativeError = fromEnum status
477+ , sqlErrorMsg = B.concat [ "query: ", statusmsg
478+ , ": ", errormsg ]}
479+
480+-- | Of the four isolation levels defined by the SQL standard,
481+-- these are the three levels distinguished by PostgreSQL as of version 9.0.
482+-- See <http://www.postgresql.org/docs/9.1/static/transaction-iso.html>
483+-- for more information.
484+
485+data IsolationLevel
486+ = ReadCommitted
487+ | RepeatableRead
488+ | Serializable
489+ deriving (Show, Eq, Ord, Enum, Bounded)
490+
491+data ReadWriteMode
492+ = ReadWrite
493+ | ReadOnly
494+ deriving (Show, Eq, Ord, Enum, Bounded)
495+
496+data TransactionMode = TransactionMode {
497+ isolationLevel :: !IsolationLevel,
498+ readWriteMode :: !ReadWriteMode
499+ } deriving (Show, Eq, Ord)
500+
501+defaultTransactionMode :: TransactionMode
502+defaultTransactionMode = TransactionMode ReadCommitted ReadWrite
503+
504+-- | Execute an action inside a SQL transaction.
505+--
506+-- This function initiates a transaction with a \"@begin
507+-- transaction@\" statement, then executes the supplied action. If
508+-- the action succeeds, the transaction will be completed with
509+-- 'Base.commit' before this function returns.
510+--
511+-- If the action throws /any/ kind of exception (not just a
512+-- PostgreSQL-related exception), the transaction will be rolled back using
513+-- 'rollback', then the exception will be rethrown.
514+withTransaction :: Connection -> IO a -> IO a
515+withTransaction = withTransactionMode defaultTransactionMode
516+
517+-- | Execute an action inside a SQL transaction with a given isolation level.
518+withTransactionMode :: TransactionMode -> Connection -> IO a -> IO a
519+withTransactionMode mode conn act = do
520+ beginMode mode conn
521+ r <- act `onException` rollback conn
522+ commit conn
523+ return r
524+
525+-- | Rollback a transaction.
526+rollback :: Connection -> IO ()
527+rollback conn = execute_ conn "ABORT" >> return ()
528+
529+-- | Commit a transaction.
530+commit :: Connection -> IO ()
531+commit conn = execute_ conn "COMMIT" >> return ()
532+
533+-- | Begin a transaction.
534+begin :: Connection -> IO ()
535+begin = beginMode defaultTransactionMode
536+
537+-- | Begin a transaction with a given isolation level
538+beginMode :: TransactionMode -> Connection -> IO ()
539+beginMode mode conn = do
540+ execute_ conn $! case mode of
541+ TransactionMode ReadCommitted ReadWrite ->
542+ "BEGIN"
543+ TransactionMode ReadCommitted ReadOnly ->
544+ "BEGIN READ ONLY"
545+ TransactionMode RepeatableRead ReadWrite ->
546+ "BEGIN ISOLATION LEVEL REPEATABLE READ"
547+ TransactionMode RepeatableRead ReadOnly ->
548+ "BEGIN ISOLATION LEVEL REPEATABLE READ READ ONLY"
549+ TransactionMode Serializable ReadWrite ->
550+ "BEGIN ISOLATION LEVEL SERIALIZABLE"
551+ TransactionMode Serializable ReadOnly ->
552+ "BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY"
553+ return ()
554+
555+fmtError :: String -> Query -> [Action] -> a
556+fmtError msg q xs = throw FormatError {
557+ fmtMessage = msg
558+ , fmtQuery = q
559+ , fmtParams = map twiddle xs
560+ }
561+ where twiddle (Plain b) = toByteString b
562+ twiddle (Escape s) = s
563+ twiddle (Many ys) = B.concat (map twiddle ys)
634564
635565-- $use
636566--
@@ -658,11 +588,9 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
658588-- >
659589-- > import Database.PostgreSQL.Simple
660590-- >
661−-- > hello :: IO Int
662591-- > hello = do
663−-- > conn <- connectPostgreSQL ""
664−-- > [Only i] <- query_ conn "select 2 + 2"
665−-- > return i
592+-- > conn <- connect defaultConnectInfo
593+-- > query conn "select 2 + 2"
666594--
667595-- A 'Query' value does not represent the actual query that will be
668596-- executed, but is a template for constructing the final query.
@@ -709,7 +637,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
709637-- Automated type inference means that you will often be able to avoid
710638-- supplying explicit type signatures for the elements of a tuple.
711639-- However, sometimes the compiler will not be able to infer your
712−-- types. Consider a case where you write a numeric literal in a
640+-- types. Consider a care where you write a numeric literal in a
713641-- parameter tuple:
714642--
715643-- > query conn "select ? + ?" (40,2)
@@ -723,30 +651,15 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
723651-- The same kind of problem can arise with string literals if you have
724652-- the @OverloadedStrings@ language extension enabled. Again, just
725653-- use an explicit type signature if this happens.
726−--
727−-- Finally, remember that the compiler must be able to infer the type
728−-- of a query's /results/ as well as its parameters. We might like
729−-- the following example to work:
730−--
731−-- > print =<< query_ conn "select 2 + 2"
732−--
733−-- Unfortunately, while a quick glance tells us that the result type
734−-- should be a single row containing a single numeric column, the
735−-- compiler has no way to infer what the types are. We can easily fix
736−-- this by providing an explicit type annotation:
737−--
738−-- > xs <- query_ conn "select 2 + 2"
739−-- > print (xs :: [Only Int])
740654
741655-- $only_param
742656--
743657-- Haskell lacks a single-element tuple type, so if you have just one
744−-- value you want substituted into a query or a single-column result,
745−-- what should you do?
658+-- value you want substituted into a query, what should you do?
746659--
747660-- The obvious approach would appear to be something like this:
748661--
749−-- > instance (ToField a) => ToRow a where
662+-- > instance (Param a) => QueryParam a where
750663-- > ...
751664--
752665-- Unfortunately, this wreaks havoc with type inference, so we take a
@@ -757,9 +670,6 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
757670--
758671-- > execute conn "insert into users (first_name) values (?)"
759672-- > ["Nuala"]
760−--
761−-- A row of /n/ query results is represented using an /n/-tuple, so
762−-- you should use 'Only' to represent a single-column result.
763673
764674-- $in
765675--
@@ -777,7 +687,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
777687-- Here's an example:
778688--
779689-- > query conn "select * from users where first_name in ?" $
780−-- > Only $ In ["Anna", "Boris", "Carla"]
690+-- > In ["Anna", "Boris", "Carla"]
781691--
782692-- If your 'In'-wrapped list is empty, the string @\"(null)\"@ will be
783693-- substituted instead, to ensure that your clause remains
@@ -805,7 +715,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
805715-- * There must be no other \"@?@\" characters anywhere in your
806716-- template.
807717--
808−-- * There must be one or more \"@?@\" in the parentheses.
718+-- * There must one or more \"@?@\" in the parentheses.
809719--
810720-- * Extra white space is fine.
811721--
@@ -826,26 +736,10 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
826736-- > insert into users (first_name,last_name) values
827737-- > ('Boris','Karloff'),('Ed','Wood')
828738
829−-- $returning
830−--
831−-- PostgreSQL supports returning values from data manipulation statements
832−-- such as @INSERT@ and @UPDATE@. You can use these statements by
833−-- using 'query' instead of 'execute'. For multi-tuple inserts,
834−-- use 'returning' instead of 'executeMany'.
835−--
836−-- For example, were there an auto-incrementing @id@ column and
837−-- timestamp column @t@ that defaulted to the present time for the
838−-- @sales@ table, then the following query would insert two new
839−-- sales records and also return their new @id@s and timestamps.
840−--
841−-- > let q = "insert into sales (amount, label) values (?,?) returning id, t"
842−-- > xs :: [(Int, UTCTime)] <- query conn q (15,"Sawdust")
843−-- > ys :: [(Int, UTCTime)] <- returning conn q [(20,"Chips"),(300,"Wood")]
844−
845739-- $result
846740--
847741-- The 'query' and 'query_' functions return a list of values in the
848−-- 'FromRow' typeclass. This class performs automatic extraction
742+-- 'QueryResults' typeclass. This class performs automatic extraction
849743-- and type conversion of rows from a query result.
850744--
851745-- Here is a simple example of how to extract results:
@@ -876,7 +770,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
876770--
877771-- Although SQL can accommodate @NULL@ as a value for any of these
878772-- types, Haskell cannot. If your result contains columns that may be
879−-- @NULL@, be sure that you use 'Maybe' in those positions of your
773+-- @NULL@, be sure that you use 'Maybe' in those positions of of your
880774-- tuple.
881775--
882776-- > (Text, Maybe Int, Int)
@@ -902,7 +796,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
902796-- all values of the given PostgreSQL type is considered \"compatible\".
903797-- For instance, you can always extract a PostgreSQL 16-bit @SMALLINT@
904798-- column to a Haskell 'Int'. The Haskell 'Float' type can accurately
905−-- represent a @SMALLINT@, so it is considered compatible with those types.
799+-- represent a @SMALLINT@, so it is considered compatble with those types.
906800--
907801-- * A numeric compatibility check is based only on the type of a
908802-- column, /not/ on its values. For instance, a PostgreSQL 64-bit
@@ -916,3 +810,25 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
916810-- UTF-8. If you use some other encoding, decoding may fail or give
917811-- wrong results. In such cases, write a @newtype@ wrapper and a
918812-- custom 'Result' instance to handle your encoding.
813+
814+getTypename :: Connection -> PQ.Oid -> IO ByteString
815+getTypename conn@Connection{..} oid =
816+ case oid2builtin oid of
817+ Just builtin -> return $! builtin2typname builtin
818+ Nothing -> modifyMVar connectionObjects $ \oidmap -> do
819+ case IntMap.lookup (oid2int oid) oidmap of
820+ Just name -> return (oidmap, name)
821+ Nothing -> do
822+ names <- query conn "SELECT typname FROM pg_type WHERE oid=?"
823+ (Only oid)
824+ name <- case names of
825+ [] -> return $ throw SqlError {
826+ sqlNativeError = -1,
827+ sqlErrorMsg = "invalid type oid",
828+ sqlState = ""
829+ }
830+ [Only x] -> return x
831+ _ -> fail "typename query returned more than one result"
832+ -- oid is a primary key, so the query should
833+ -- never return more than one result
834+ return (IntMap.insert (oid2int oid) name oidmap, name)