@@ -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 +85,18 @@ module Database.PostgreSQL.Simple
11085-- , Base.insertID
11186 -- * Transaction handling
11287 , withTransaction
113− , withSavepoint
88+ , TransactionMode(..)
89+ , IsolationLevel(..)
90+ , ReadWriteMode(..)
91+ , defaultTransactionMode
92+ , defaultIsolationLevel
93+ , defaultReadWriteMode
94+ , withTransactionLevel
95+ , withTransactionMode
11496-- , Base.autocommit
11597 , begin
98+ , beginLevel
99+ , beginMode
116100 , commit
117101 , rollback
118102 -- * Helper functions
@@ -120,27 +104,50 @@ module Database.PostgreSQL.Simple
120104 , formatQuery
121105 ) where
122106
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
107+import Blaze.ByteString.Builder (Builder, fromByteString, toByteString)
108+import Blaze.ByteString.Builder.Char8 (fromChar)
109+import Control.Applicative ((<$>), pure)
110+import Control.Concurrent.MVar
111+import Control.Exception (Exception, onException, throw, throwIO, finally)
112+import Control.Monad (foldM)
113+import Data.ByteString (ByteString)
114+import Data.Char(ord)
115+import Data.Int (Int64)
116+import qualified Data.IntMap as IntMap
117+import Data.List (intersperse)
118+import Data.Monoid (mappend, mconcat)
119+import Data.Typeable (Typeable)
120+import Database.PostgreSQL.Simple.BuiltinTypes (oid2builtin, builtin2typname)
121+import Database.PostgreSQL.Simple.Compat (mask)
122+import Database.PostgreSQL.Simple.Param (Action(..), inQuotes)
123+import Database.PostgreSQL.Simple.QueryParams (QueryParams(..))
124+import Database.PostgreSQL.Simple.Result (ResultError(..))
125+import Database.PostgreSQL.Simple.QueryResults (QueryResults(..))
126+import Database.PostgreSQL.Simple.Types (Binary(..), In(..), Only(..), Query(..))
127+import Database.PostgreSQL.Simple.Internal as Base
141128import qualified Database.PostgreSQL.LibPQ as PQ
129+import Text.Regex.PCRE.Light (compile, caseless, match)
142130import qualified Data.ByteString.Char8 as B
143131
132+-- | Exception thrown if a 'Query' could not be formatted correctly.
133+-- This may occur if the number of \'@?@\' characters in the query
134+-- string does not match the number of parameters provided.
135+data FormatError = FormatError {
136+ fmtMessage :: String
137+ , fmtQuery :: Query
138+ , fmtParams :: [ByteString]
139+ } deriving (Eq, Show, Typeable)
140+
141+instance Exception FormatError
142+
143+-- | Exception thrown if 'query' is used to perform an @INSERT@-like
144+-- operation, or 'execute' is used to perform a @SELECT@-like operation.
145+data QueryError = QueryError {
146+ qeMessage :: String
147+ , qeQuery :: Query
148+ } deriving (Eq, Show, Typeable)
149+
150+instance Exception QueryError
144151
145152-- | Format a query string.
146153--
@@ -152,11 +159,11 @@ import qualified Data.ByteString.Char8 as B
152159--
153160-- Throws 'FormatError' if the query string could not be formatted
154161-- correctly.
155−formatQuery :: ToRow q => Connection -> Query -> q -> IO ByteString
162+formatQuery :: QueryParams q => Connection -> Query -> q -> IO ByteString
156163formatQuery conn q@(Query template) qs
157164 | null xs && '?' `B.notElem` template = return template
158165 | otherwise = toByteString <$> buildQuery conn q template xs
159− where xs = toRow qs
166+ where xs = renderParams qs
160167
161168-- | Format a query string with a variable number of rows.
162169--
@@ -171,208 +178,106 @@ formatQuery conn q@(Query template) qs
171178--
172179-- Throws 'FormatError' if the query string could not be formatted
173180-- correctly.
174−formatMany :: (ToRow q) => Connection -> Query -> [q] -> IO ByteString
181+formatMany :: (QueryParams q) => Connection -> Query -> [q] -> IO ByteString
175182formatMany _ q [] = fmtError "no rows supplied" q []
176183formatMany 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
184+ case match re template [] of
185+ Just [_,before,qbits,after] -> do
186+ bs <- mapM (buildQuery conn q qbits . renderParams) qs
187+ return . toByteString . mconcat $ fromByteString before :
188+ intersperse (fromChar ',') bs ++
189+ [fromByteString after]
190+ _ -> error "foo"
203191 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
192+ re = compile "^([^?]+\\bvalues\\s*)\
193+ \(\\(\\s*[?](?:\\s*,\\s*[?])*\\s*\\))\
194+ \([^?]*)$"
195+ [caseless]
279196
197+escapeStringConn :: Connection -> ByteString -> IO (Maybe ByteString)
198+escapeStringConn conn s = withConnection conn $ \c -> do
199+ PQ.escapeStringConn c s
280200
281201buildQuery :: Connection -> Query -> ByteString -> [Action] -> IO Builder
282−buildQuery conn q template xs =
283− zipParams (split template) <$> mapM (buildAction conn q xs) xs
284− where split s =
285− -- This part escapes double '??'s to make literal '?'s possible
286− -- in PostgreSQL queries using the JSON operators: @?@, @?|@ and @?&@
287− let (h,t) = breakOnSingleQuestionMark s
288− in byteString h
289− : if B.null t
290− then []
291− else split (B.tail t)
292− zipParams (t:ts) (p:ps) = t <> p <> zipParams ts ps
202+buildQuery conn q template xs = zipParams (split template) <$> mapM sub xs
203+ where quote = inQuotes . fromByteString . maybe undefined id
204+ sub (Plain b) = pure b
205+ sub (Escape s) = quote <$> escapeStringConn conn s
206+ sub (Many ys) = mconcat <$> mapM sub ys
207+ split s = fromByteString h : if B.null t then [] else split (B.tail t)
208+ where (h,t) = B.break (=='?') s
209+ zipParams (t:ts) (p:ps) = t `mappend` p `mappend` zipParams ts ps
293210 zipParams [t] [] = t
294− zipParams _ _ = fmtError (show countSingleQs ++
295− " single '?' characters, but " ++
211+ zipParams _ _ = fmtError (show (B.count '?' template) ++
212+ " '?' characters, but " ++
296213 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
306214
307215-- | Execute an @INSERT@, @UPDATE@, or other SQL query that is not
308216-- expected to return results.
309217--
310218-- Returns the number of rows affected.
311219--
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
220+-- Throws 'FormatError' if the query could not be formatted correctly.
221+execute :: (QueryParams q) => Connection -> Query -> q -> IO Int64
315222execute conn template qs = do
316223 result <- exec conn =<< formatQuery conn template qs
317224 finishExecute conn template result
318225
226+-- | A version of 'execute' that does not perform query substitution.
227+execute_ :: Connection -> Query -> IO Int64
228+execute_ conn q@(Query stmt) = do
229+ result <- exec conn stmt
230+ finishExecute conn q result
231+
319232-- | Execute a multi-row @INSERT@, @UPDATE@, or other SQL query that is not
320233-- expected to return results.
321234--
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:
235+-- Returns the number of rows affected.
339236--
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
237+-- Throws 'FormatError' if the query could not be formatted correctly.
238+executeMany :: (QueryParams q) => Connection -> Query -> [q] -> IO Int64
350239executeMany _ _ [] = return 0
351240executeMany conn q qs = do
352241 result <- exec conn =<< formatMany conn q qs
353242 finishExecute conn q result
354243
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
244+finishExecute :: Connection -> Query -> PQ.Result -> IO Int64
245+finishExecute _conn q result = do
246+ status <- PQ.resultStatus result
247+ case status of
248+ PQ.CommandOk -> do
249+ ncols <- PQ.nfields result
250+ if ncols /= 0
251+ then throwIO $ QueryError ("execute resulted in " ++ show ncols ++
252+ "-column result") q
253+ else do
254+ nstr <- PQ.cmdTuples result
255+ return $ case nstr of
256+ Nothing -> 0 -- is this appropriate?
257+ Just str -> toInteger str
258+ PQ.TuplesOk -> do
259+ ncols <- PQ.nfields result
260+ throwIO $ QueryError ("execute resulted in " ++ show ncols ++
261+ "-column result") q
262+ PQ.CopyIn -> fail "FIXME: postgresql-simple does not currently support COPY IN"
263+ PQ.CopyOut -> fail "FIXME: postgresql-simple does not currently support COPY OUT"
264+ _ -> do
265+ errormsg <- maybe "" id <$> PQ.resultErrorMessage result
266+ statusmsg <- PQ.resStatus status
267+ state <- maybe "" id <$> PQ.resultErrorField result PQ.DiagSqlstate
268+ throwIO $ SqlError { sqlState = state
269+ , sqlNativeError = fromEnum status
270+ , sqlErrorMsg = B.concat [ "execute: ", statusmsg
271+ , ": ", errormsg ]}
272+ where
273+ toInteger str = B.foldl' delta 0 str
274+ where
275+ delta acc c =
276+ if '0' <= c && c <= '9'
277+ then 10 * acc + fromIntegral (ord c - ord '0')
278+ else error ("finishExecute: not an int: " ++ B.unpack str)
279+
369280
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
376281
377282-- | Perform a @SELECT@ or other SQL query that is expected to return
378283-- results. All results are retrieved and converted before this
@@ -389,27 +294,17 @@ returningWith parser conn q qs = do
389294-- using 'execute' instead of 'query').
390295--
391296-- * '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
297+query :: (QueryParams q, QueryResults r)
298+ => Connection -> Query -> q -> IO [r]
299+query conn template qs = do
405300 result <- exec conn =<< formatQuery conn template qs
406− finishQueryWith parser conn template result
301+ finishQuery conn template result
407302
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
303+-- | A version of 'query' that does not perform query substitution.
304+query_ :: (QueryResults r) => Connection -> Query -> IO [r]
305+query_ conn q@(Query que) = do
411306 result <- exec conn que
412− finishQueryWith parser conn q result
307+ finishQuery conn q result
413308
414309-- | Perform a @SELECT@ or other SQL query that is expected to return
415310-- results. Results are streamed incrementally from the server, and
@@ -421,12 +316,6 @@ queryWith_ parser conn q@(Query que) = do
421316-- This fold is /not/ strict. The stream consumer is responsible for
422317-- forcing the evaluation of its result to avoid space leaks.
423318--
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−--
430319-- Exceptions that may be thrown:
431320--
432321-- * 'FormatError': the query string could not be formatted correctly.
@@ -435,10 +324,8 @@ queryWith_ parser conn q@(Query que) = do
435324-- using 'execute' instead of 'query').
436325--
437326-- * '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 )
327+
328+fold :: ( QueryResults row, QueryParams params )
442329 => Connection
443330 -> Query
444331 -> params
@@ -447,20 +334,6 @@ fold :: ( FromRow row, ToRow params )
447334 -> IO a
448335fold = foldWithOptions defaultFoldOptions
449336
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.
464337data FetchQuantity
465338 = Automatic
466339 | Fixed !Int
@@ -471,20 +344,13 @@ data FoldOptions
471344 transactionMode :: !TransactionMode
472345 }
473346
474−-- | defaults to 'Automatic', and 'TransactionMode' 'ReadCommitted' 'ReadOnly'
475347defaultFoldOptions :: FoldOptions
476348defaultFoldOptions = FoldOptions {
477349 fetchQuantity = Automatic,
478350 transactionMode = TransactionMode ReadCommitted ReadOnly
479351 }
480352
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 )
353+foldWithOptions :: ( QueryResults row, QueryParams params )
488354 => FoldOptions
489355 -> Connection
490356 -> Query
@@ -492,24 +358,12 @@ foldWithOptions :: ( FromRow row, ToRow params )
492358 -> a
493359 -> (a -> row -> IO a)
494360 -> 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
361+foldWithOptions opts conn template qs a f = do
508362 q <- formatQuery conn template qs
509− doFold opts parser conn template (Query q) a f
363+ doFold opts conn template (Query q) a f
510364
511365-- | A version of 'fold' that does not perform query substitution.
512−fold_ :: (FromRow r) =>
366+fold_ :: (QueryResults r) =>
513367 Connection
514368 -> Query -- ^ Query.
515369 -> a -- ^ Initial state for result consumer.
@@ -517,43 +371,26 @@ fold_ :: (FromRow r) =>
517371 -> IO a
518372fold_ = foldWithOptions_ defaultFoldOptions
519373
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
528374
529−foldWithOptions_ :: (FromRow r) =>
375+foldWithOptions_ :: (QueryResults r) =>
530376 FoldOptions
531377 -> Connection
532378 -> Query -- ^ Query.
533379 -> a -- ^ Initial state for result consumer.
534380 -> (a -> r -> IO a) -- ^ Result consumer.
535381 -> 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
382+foldWithOptions_ opts conn query a f = doFold opts conn query query a f
383+
384+
385+doFold :: ( QueryResults row )
386+ => FoldOptions
550387 -> Connection
551388 -> Query
552389 -> Query
553390 -> a
554391 -> (a -> row -> IO a)
555392 -> IO a
556−doFold FoldOptions{..} parser conn _template q a0 f = do
393+doFold FoldOptions{..} conn _template q a f = do
557394 stat <- withConnection conn PQ.transactionStatus
558395 case stat of
559396 PQ.TransIdle -> withTransactionMode transactionMode conn go
@@ -571,17 +408,11 @@ doFold FoldOptions{..} parser conn _template q a0 f = do
571408 PQ.TransUnknown -> fail "foldWithOpts FIXME: PQ.TransUnknown"
572409 -- Not sure what this means.
573410 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
411+ go = do
412+ -- FIXME: what about name clashes with already-declared cursors?
413+ _ <- execute_ conn ("DECLARE fold NO SCROLL CURSOR FOR "
414+ `mappend` q)
415+ loop a `finally` execute_ conn "CLOSE fold"
585416
586417-- FIXME: choose the Automatic chunkSize more intelligently
587418-- One possibility is to use the type of the results, although this
@@ -592,45 +423,168 @@ doFold FoldOptions{..} parser conn _template q a0 f = do
592423 chunkSize = case fetchQuantity of
593424 Automatic -> 256
594425 Fixed n -> n
426+ loop a = do
427+ rs <- query conn "FETCH FORWARD ? FROM fold" (Only chunkSize)
428+ if null rs then return a else foldM f a rs >>= loop
595429
596430-- | A version of 'fold' that does not transform a state value.
597−forEach :: (ToRow q, FromRow r) =>
431+forEach :: (QueryParams q, QueryResults r) =>
598432 Connection
599433 -> Query -- ^ Query template.
600434 -> q -- ^ Query parameters.
601435 -> (r -> IO ()) -- ^ Result consumer.
602436 -> IO ()
603−forEach = forEachWith fromRow
437+forEach conn template qs = fold conn template qs () . const
604438{-# INLINE forEach #-}
605439
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−
617440-- | A version of 'forEach' that does not perform query substitution.
618−forEach_ :: (FromRow r) =>
441+forEach_ :: (QueryResults r) =>
619442 Connection
620443 -> Query -- ^ Query template.
621444 -> (r -> IO ()) -- ^ Result consumer.
622445 -> IO ()
623−forEach_ = forEachWith_ fromRow
446+forEach_ conn template = fold_ conn template () . const
624447{-# INLINE forEach_ #-}
625448
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−
449+forM' :: (Ord n, Num n) => n -> n -> (n -> IO a) -> IO [a]
450+forM' lo hi m = loop hi []
451+ where
452+ loop !n !as
453+ | n < lo = return as
454+ | otherwise = do
455+ a <- m n
456+ loop (n-1) (a:as)
457+
458+finishQuery :: (QueryResults r) => Connection -> Query -> PQ.Result -> IO [r]
459+finishQuery conn q result = do
460+ status <- PQ.resultStatus result
461+ case status of
462+ PQ.CommandOk -> do
463+ throwIO $ QueryError "query resulted in a command response" q
464+ PQ.TuplesOk -> do
465+ ncols <- PQ.nfields result
466+ fields <- forM' 0 (ncols-1) $ \column -> do
467+ type_oid <- PQ.ftype result column
468+ typename <- getTypename conn type_oid
469+ return Field{..}
470+ nrows <- PQ.ntuples result
471+ forM' 0 (nrows-1) $ \row -> do
472+ values <- forM' 0 (ncols-1) (\col -> PQ.getvalue result row col)
473+ case convertResults fields values of
474+ Left err -> throwIO err
475+ Right a -> return a
476+ PQ.CopyIn -> fail "FIXME: postgresql-simple does not currently support COPY IN"
477+ PQ.CopyOut -> fail "FIXME: postgresql-simple does not currently support COPY OUT"
478+ _ -> do
479+ errormsg <- maybe "" id <$> PQ.resultErrorMessage result
480+ statusmsg <- PQ.resStatus status
481+ state <- maybe "" id <$> PQ.resultErrorField result PQ.DiagSqlstate
482+ throwIO $ SqlError { sqlState = state
483+ , sqlNativeError = fromEnum status
484+ , sqlErrorMsg = B.concat [ "query: ", statusmsg
485+ , ": ", errormsg ]}
486+
487+-- | Of the four isolation levels defined by the SQL standard,
488+-- these are the three levels distinguished by PostgreSQL as of version 9.0.
489+-- See <http://www.postgresql.org/docs/9.1/static/transaction-iso.html>
490+-- for more information.
491+
492+data IsolationLevel
493+ = ReadCommitted
494+ | RepeatableRead
495+ | Serializable
496+ deriving (Show, Eq, Ord, Enum, Bounded)
497+
498+data ReadWriteMode
499+ = ReadWrite
500+ | ReadOnly
501+ deriving (Show, Eq, Ord, Enum, Bounded)
502+
503+data TransactionMode = TransactionMode {
504+ isolationLevel :: !IsolationLevel,
505+ readWriteMode :: !ReadWriteMode
506+ } deriving (Show, Eq)
507+
508+defaultTransactionMode :: TransactionMode
509+defaultTransactionMode = TransactionMode ReadCommitted ReadWrite
510+
511+defaultIsolationLevel :: IsolationLevel
512+defaultIsolationLevel = ReadCommitted
513+
514+defaultReadWriteMode :: ReadWriteMode
515+defaultReadWriteMode = ReadWrite
516+
517+-- | Execute an action inside a SQL transaction.
518+--
519+-- This function initiates a transaction with a \"@begin
520+-- transaction@\" statement, then executes the supplied action. If
521+-- the action succeeds, the transaction will be completed with
522+-- 'Base.commit' before this function returns.
523+--
524+-- If the action throws /any/ kind of exception (not just a
525+-- PostgreSQL-related exception), the transaction will be rolled back using
526+-- 'rollback', then the exception will be rethrown.
527+withTransaction :: Connection -> IO a -> IO a
528+withTransaction = withTransactionMode defaultTransactionMode
529+
530+-- | Execute an action inside a SQL transaction with a given isolation level.
531+withTransactionLevel :: IsolationLevel -> Connection -> IO a -> IO a
532+withTransactionLevel lvl
533+ = withTransactionMode defaultTransactionMode { isolationLevel = lvl }
534+
535+-- | Execute an action inside a SQL transaction with a given transaction mode.
536+withTransactionMode :: TransactionMode -> Connection -> IO a -> IO a
537+withTransactionMode mode conn act =
538+ mask $ \restore -> do
539+ beginMode mode conn
540+ r <- restore act `onException` rollback conn
541+ commit conn
542+ return r
543+
544+-- | Rollback a transaction.
545+rollback :: Connection -> IO ()
546+rollback conn = execute_ conn "ABORT" >> return ()
547+
548+-- | Commit a transaction.
549+commit :: Connection -> IO ()
550+commit conn = execute_ conn "COMMIT" >> return ()
551+
552+-- | Begin a transaction.
553+begin :: Connection -> IO ()
554+begin = beginMode defaultTransactionMode
555+
556+-- | Begin a transaction with a given isolation level
557+beginLevel :: IsolationLevel -> Connection -> IO ()
558+beginLevel lvl = beginMode defaultTransactionMode { isolationLevel = lvl }
559+
560+-- | Begin a transaction with a given transaction mode
561+beginMode :: TransactionMode -> Connection -> IO ()
562+beginMode mode conn = do
563+ _ <- execute_ conn $!
564+ case mode of
565+ TransactionMode ReadCommitted ReadWrite ->
566+ "BEGIN"
567+ TransactionMode ReadCommitted ReadOnly ->
568+ "BEGIN READ ONLY"
569+ TransactionMode RepeatableRead ReadWrite ->
570+ "BEGIN ISOLATION LEVEL REPEATABLE READ"
571+ TransactionMode RepeatableRead ReadOnly ->
572+ "BEGIN ISOLATION LEVEL REPEATABLE READ READ ONLY"
573+ TransactionMode Serializable ReadWrite ->
574+ "BEGIN ISOLATION LEVEL SERIALIZABLE"
575+ TransactionMode Serializable ReadOnly ->
576+ "BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY"
577+ return ()
578+
579+fmtError :: String -> Query -> [Action] -> a
580+fmtError msg q xs = throw FormatError {
581+ fmtMessage = msg
582+ , fmtQuery = q
583+ , fmtParams = map twiddle xs
584+ }
585+ where twiddle (Plain b) = toByteString b
586+ twiddle (Escape s) = s
587+ twiddle (Many ys) = B.concat (map twiddle ys)
634588
635589-- $use
636590--
@@ -658,11 +612,9 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
658612-- >
659613-- > import Database.PostgreSQL.Simple
660614-- >
661−-- > hello :: IO Int
662615-- > hello = do
663−-- > conn <- connectPostgreSQL ""
664−-- > [Only i] <- query_ conn "select 2 + 2"
665−-- > return i
616+-- > conn <- connect defaultConnectInfo
617+-- > query conn "select 2 + 2"
666618--
667619-- A 'Query' value does not represent the actual query that will be
668620-- executed, but is a template for constructing the final query.
@@ -709,7 +661,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
709661-- Automated type inference means that you will often be able to avoid
710662-- supplying explicit type signatures for the elements of a tuple.
711663-- However, sometimes the compiler will not be able to infer your
712−-- types. Consider a case where you write a numeric literal in a
664+-- types. Consider a care where you write a numeric literal in a
713665-- parameter tuple:
714666--
715667-- > query conn "select ? + ?" (40,2)
@@ -723,30 +675,15 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
723675-- The same kind of problem can arise with string literals if you have
724676-- the @OverloadedStrings@ language extension enabled. Again, just
725677-- 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])
740678
741679-- $only_param
742680--
743681-- 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?
682+-- value you want substituted into a query, what should you do?
746683--
747684-- The obvious approach would appear to be something like this:
748685--
749−-- > instance (ToField a) => ToRow a where
686+-- > instance (Param a) => QueryParam a where
750687-- > ...
751688--
752689-- Unfortunately, this wreaks havoc with type inference, so we take a
@@ -757,9 +694,6 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
757694--
758695-- > execute conn "insert into users (first_name) values (?)"
759696-- > ["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.
763697
764698-- $in
765699--
@@ -777,7 +711,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
777711-- Here's an example:
778712--
779713-- > query conn "select * from users where first_name in ?" $
780−-- > Only $ In ["Anna", "Boris", "Carla"]
714+-- > In ["Anna", "Boris", "Carla"]
781715--
782716-- If your 'In'-wrapped list is empty, the string @\"(null)\"@ will be
783717-- substituted instead, to ensure that your clause remains
@@ -805,7 +739,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
805739-- * There must be no other \"@?@\" characters anywhere in your
806740-- template.
807741--
808−-- * There must be one or more \"@?@\" in the parentheses.
742+-- * There must one or more \"@?@\" in the parentheses.
809743--
810744-- * Extra white space is fine.
811745--
@@ -826,26 +760,10 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
826760-- > insert into users (first_name,last_name) values
827761-- > ('Boris','Karloff'),('Ed','Wood')
828762
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−
845763-- $result
846764--
847765-- The 'query' and 'query_' functions return a list of values in the
848−-- 'FromRow' typeclass. This class performs automatic extraction
766+-- 'QueryResults' typeclass. This class performs automatic extraction
849767-- and type conversion of rows from a query result.
850768--
851769-- Here is a simple example of how to extract results:
@@ -876,7 +794,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
876794--
877795-- Although SQL can accommodate @NULL@ as a value for any of these
878796-- types, Haskell cannot. If your result contains columns that may be
879−-- @NULL@, be sure that you use 'Maybe' in those positions of your
797+-- @NULL@, be sure that you use 'Maybe' in those positions of of your
880798-- tuple.
881799--
882800-- > (Text, Maybe Int, Int)
@@ -902,7 +820,7 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
902820-- all values of the given PostgreSQL type is considered \"compatible\".
903821-- For instance, you can always extract a PostgreSQL 16-bit @SMALLINT@
904822-- column to a Haskell 'Int'. The Haskell 'Float' type can accurately
905−-- represent a @SMALLINT@, so it is considered compatible with those types.
823+-- represent a @SMALLINT@, so it is considered compatble with those types.
906824--
907825-- * A numeric compatibility check is based only on the type of a
908826-- column, /not/ on its values. For instance, a PostgreSQL 64-bit
@@ -916,3 +834,25 @@ forEachWith_ parser conn template = foldWith_ parser conn template () . const
916834-- UTF-8. If you use some other encoding, decoding may fail or give
917835-- wrong results. In such cases, write a @newtype@ wrapper and a
918836-- custom 'Result' instance to handle your encoding.
837+
838+getTypename :: Connection -> PQ.Oid -> IO ByteString
839+getTypename conn@Connection{..} oid =
840+ case oid2builtin oid of
841+ Just builtin -> return $! builtin2typname builtin
842+ Nothing -> modifyMVar connectionObjects $ \oidmap -> do
843+ case IntMap.lookup (oid2int oid) oidmap of
844+ Just name -> return (oidmap, name)
845+ Nothing -> do
846+ names <- query conn "SELECT typname FROM pg_type WHERE oid=?"
847+ (Only oid)
848+ name <- case names of
849+ [] -> return $ throw SqlError {
850+ sqlNativeError = -1,
851+ sqlErrorMsg = "invalid type oid",
852+ sqlState = ""
853+ }
854+ [Only x] -> return x
855+ _ -> fail "typename query returned more than one result"
856+ -- oid is a primary key, so the query should
857+ -- never return more than one result
858+ return (IntMap.insert (oid2int oid) name oidmap, name)