@@ -1,16 +1,23 @@
1−{-# LANGUAGE BangPatterns, DeriveDataTypeable, OverloadedStrings, DoAndIfThenElse, RecordWildCards, NamedFieldPuns #-}
1+{-# LANGUAGE DeriveDataTypeable #-}
2−
2+{-# LANGUAGE NamedFieldPuns #-}
3+{-# LANGUAGE OverloadedStrings #-}
4+{-# LANGUAGE PatternGuards #-}
5+{-# LANGUAGE RecordWildCards #-}
6+{-# LANGUAGE ViewPatterns #-}
8+------------------------------------------------------------------------------
4-- Module: Database.PostgreSQL.Simple
10-- Module: Database.PostgreSQL.Simple
5-- Copyright: (c) 2011 MailRank, Inc.
11-- Copyright: (c) 2011 MailRank, Inc.
6−-- (c) 2011 Leon P Smith
12+-- (c) 2011-2012 Leon P Smith
7-- License: BSD3
13-- License: BSD3
8-- Maintainer: Leon P Smith <leon@melding-monads.com>
14-- Maintainer: Leon P Smith <leon@melding-monads.com>
9-- Stability: experimental
15-- Stability: experimental
10−-- Portability: portable
12−-- A mid-level client library for the MySQL database, aimed at ease of
17+-- A mid-level client library for the PostgreSQL database, aimed at ease of
13-- use and high performance.
18-- use and high performance.
20+------------------------------------------------------------------------------
15module Database.PostgreSQL.Simple
22module Database.PostgreSQL.Simple
@@ -35,6 +42,9 @@ module Database.PostgreSQL.Simple
35 -- ** Modifying multiple rows at once
42 -- ** Modifying multiple rows at once
45+ -- ** @RETURNING@: modifications that return results
38 -- * Extracting results
48 -- * Extracting results
39 -- $result
49 -- $result
@@ -45,32 +55,54 @@ module Database.PostgreSQL.Simple
47 -- * Types
57 -- * Types
49− , Connection
58+ Connection
52 , Binary(..)
63 , Binary(..)
53 , Only(..)
64 , Only(..)
54 -- ** Exceptions
66 -- ** Exceptions
67+ , SomePostgreSqlException(..)
55− , FormatError(fmtMessage, fmtQuery, fmtParams)
70+ , FormatError(..)
56− , QueryError(qeMessage, qeQuery)
71+ , QueryError(..)
57− , ResultError(errSQLType, errHaskellType, errMessage)
72+ , ResultError(..)
58 -- * Connection management
73 -- * Connection management
60 , Base.connectPostgreSQL
74 , Base.connectPostgreSQL
61− , Base.postgreSQLConnectionString
62− , Base.defaultConnectInfo
63 , Base.close
75 , Base.close
78+ , Base.ConnectInfo(..)
79+ , Base.defaultConnectInfo
80+ , Base.postgreSQLConnectionString
64 -- * Queries that return results
81 -- * Queries that return results
67−{--
84+ -- ** Queries taking parser as argument
68 -- * Queries that stream results
87 -- * Queries that stream results
72 , forEach_
96 , forEach_
98+ -- ** Queries that stream results taking a parser as an argument
100+ , foldWithOptionsAndParser
102+ , foldWithOptionsAndParser_
74 -- * Statements that do not return results
106 -- * Statements that do not return results
75 , execute
107 , execute
76 , execute_
108 , execute_
@@ -78,6 +110,7 @@ module Database.PostgreSQL.Simple
78-- , Base.insertID
110-- , Base.insertID
79 -- * Transaction handling
111 -- * Transaction handling
80 , withTransaction
112 , withTransaction
81-- , Base.autocommit
114-- , Base.autocommit
@@ -87,55 +120,27 @@ module Database.PostgreSQL.Simple
87 , formatQuery
120 , formatQuery
90−import Blaze.ByteString.Builder (Builder, fromByteString, toByteString)
123+import Data.ByteString.Builder (Builder, byteString, char8)
91−import Blaze.ByteString.Builder.Char8 (fromChar)
92−import Control.Applicative ((<$>), pure)
124+import Control.Applicative ((<$>))
93−import Control.Concurrent.MVar
94−import Control.Exception (Exception, bracket, onException, throw, throwIO)
125+import Control.Exception as E
95−import Control.Monad (forM)
96−import Control.Monad.Fix (fix)
97−import Data.ByteString (ByteString)
126+import Data.ByteString (ByteString)
98−-- import qualified Data.ByteString as B (unpack)
100−import Data.Int (Int64)
127+import Data.Int (Int64)
101−import qualified Data.IntMap as IntMap
102−import Data.List (intersperse)
128+import Data.List (intersperse)
103−import Data.Monoid (mappend, mconcat)
129+import Data.Monoid (mconcat)
104−import Data.Typeable (Typeable)
130+import Database.PostgreSQL.Simple.Compat ((<>), toByteString)
105−--import Database.MySQL.Base (Connection, Result)
131+import Database.PostgreSQL.Simple.Cursor
106−--import Database.MySQL.Base.Types (Field)
132+import Database.PostgreSQL.Simple.FromField (ResultError(..))
107−import Database.PostgreSQL.Simple.BuiltinTypes (oid2builtin, builtin2typname)
133+import Database.PostgreSQL.Simple.FromRow (FromRow(..))
108−import Database.PostgreSQL.Simple.Param (Action(..), inQuotes)
134+import Database.PostgreSQL.Simple.ToField (Action(..))
109−import Database.PostgreSQL.Simple.QueryParams (QueryParams(..))
110−import Database.PostgreSQL.Simple.Result (ResultError(..))
135+import Database.PostgreSQL.Simple.ToRow (ToRow(..))
111−import Database.PostgreSQL.Simple.QueryResults (QueryResults(..))
136+import Database.PostgreSQL.Simple.Types
112−-- import Database.PostgreSQL.Simple.Result (ResultError(..))
113−import Database.PostgreSQL.Simple.Types (Binary(..), In(..), Only(..), Query(..))
137+ ( Binary(..), In(..), Only(..), Query(..), (:.)(..) )
114−import Database.PostgreSQL.Simple.Internal as Base
138+import Database.PostgreSQL.Simple.Internal as Base
139+import Database.PostgreSQL.Simple.Internal.PQResultUtils
140+import Database.PostgreSQL.Simple.Transaction
115import qualified Database.PostgreSQL.LibPQ as PQ
141import qualified Database.PostgreSQL.LibPQ as PQ
116−import Text.Regex.PCRE.Light (compile, caseless, match)
117import qualified Data.ByteString.Char8 as B
142import qualified Data.ByteString.Char8 as B
118−--import qualified Database.MySQL.Base as Base
120−-- | Exception thrown if a 'Query' could not be formatted correctly.
121−-- This may occur if the number of \'@?@\' characters in the query
122−-- string does not match the number of parameters provided.
123−data FormatError = FormatError {
124− fmtMessage :: String
126− , fmtParams :: [ByteString]
127− } deriving (Eq, Show, Typeable)
129−instance Exception FormatError
131−-- | Exception thrown if 'query' is used to perform an @INSERT@-like
132−-- operation, or 'execute' is used to perform a @SELECT@-like operation.
133−data QueryError = QueryError {
136− } deriving (Eq, Show, Typeable)
138−instance Exception QueryError
140-- | Format a query string.
145-- | Format a query string.
@@ -147,11 +152,11 @@ instance Exception QueryError
148-- Throws 'FormatError' if the query string could not be formatted
153-- Throws 'FormatError' if the query string could not be formatted
149-- correctly.
154-- correctly.
150−formatQuery :: QueryParams q => Connection -> Query -> q -> IO ByteString
155+formatQuery :: ToRow q => Connection -> Query -> q -> IO ByteString
151formatQuery conn q@(Query template) qs
156formatQuery conn q@(Query template) qs
152 | null xs && '?' `B.notElem` template = return template
157 | null xs && '?' `B.notElem` template = return template
153 | otherwise = toByteString <$> buildQuery conn q template xs
158 | otherwise = toByteString <$> buildQuery conn q template xs
154− where xs = renderParams qs
159+ where xs = toRow qs
156-- | Format a query string with a variable number of rows.
161-- | Format a query string with a variable number of rows.
@@ -166,106 +171,208 @@ formatQuery conn q@(Query template) qs
167-- Throws 'FormatError' if the query string could not be formatted
172-- Throws 'FormatError' if the query string could not be formatted
168-- correctly.
173-- correctly.
169−formatMany :: (QueryParams q) => Connection -> Query -> [q] -> IO ByteString
174+formatMany :: (ToRow q) => Connection -> Query -> [q] -> IO ByteString
170formatMany _ q [] = fmtError "no rows supplied" q []
175formatMany _ q [] = fmtError "no rows supplied" q []
171formatMany conn q@(Query template) qs = do
176formatMany conn q@(Query template) qs = do
172− case match re template [] of
177+ case parseTemplate template of
173− Just [_,before,qbits,after] -> do
178+ Just (before, qbits, after) -> do
174− bs <- mapM (buildQuery conn q qbits . renderParams) qs
179+ bs <- mapM (buildQuery conn q qbits . toRow) qs
175− return . toByteString . mconcat $ fromByteString before :
180+ return . toByteString . mconcat $ byteString before :
176− intersperse (fromChar ',') bs ++
181+ intersperse (char8 ',') bs ++
177− [fromByteString after]
182+ [byteString after]
178− _ -> error "foo"
183+ Nothing -> fmtError "syntax error in multi-row template" q []
185+-- Split the input string into three pieces, @before@, @qbits@, and @after@,
186+-- following this grammar:
188+-- start: ^ before qbits after $
189+-- before: ([^?]* [^?\w])? 'VALUES' \s*
190+-- qbits: '(' \s* '?' \s* (',' \s* '?' \s*)* ')'
194+-- \w: [A-Z] | [a-z] | [\x80-\xFF] | '_' | '$' | [0-9]
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
180− re = compile "^([^?]+\\bvalues\\s*)\
204+ -- Search for the next occurrence of "VALUES"
181− \(\\(\\s*[?](?:\\s*,\\s*[?])*\\s*\\))\
205+ search bs =
182− \([^?]*)$"
206+ case B.breakSubstring "VALUES" bs of
183− [caseless]
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)
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
218+ -- Otherwise, we have a legitimate "VALUES" token.
220+ -> parseQueryBits $ skipSpace $ B.drop 6 y
222+ -- Parse '(' \s* '?' \s* . If this doesn't match
223+ -- (and we don't consume a '?'), look for another "VALUES".
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.
229+ | Just ('(', skipSpace -> bs1) <- B.uncons qb
230+ , Just ('?', skipSpace -> bs2) <- B.uncons bs1
231+ = finishQueryBits qb bs2
235+ -- Parse (',' \s* '?' \s*)* ')' [^?]* .
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
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
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.
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 =
260+ (s1, source') = B.splitAt (B.length source - B.length p1) source
261+ (s2, source'') = B.splitAt (B.length p1 - B.length p2) source'
263+ toUpper_ascii c | c >= 'a' && c <= 'z' = toEnum (fromEnum c - 32)
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')
275+ -- Based on {space} in scan.l
276+ isSpace_ascii c = (c == ' ') || (c >= '\t' && c <= '\r')
278+ skipSpace = B.dropWhile isSpace_ascii
185−escapeStringConn conn s = withConnection conn $ \c -> do
186− PQ.escapeStringConn c s
188buildQuery :: Connection -> Query -> ByteString -> [Action] -> IO Builder
281buildQuery :: Connection -> Query -> ByteString -> [Action] -> IO Builder
189−buildQuery conn q template xs = zipParams (split template) <$> mapM sub xs
282+buildQuery conn q template xs =
190− where quote = inQuotes . fromByteString . maybe undefined id
283+ zipParams (split template) <$> mapM (buildAction conn q xs) xs
191− sub (Plain b) = pure b
284+ where split s =
192− sub (Escape s) = quote <$> escapeStringConn conn s
285+ -- This part escapes double '??'s to make literal '?'s possible
193− sub (Many ys) = mconcat <$> mapM sub ys
286+ -- in PostgreSQL queries using the JSON operators: @?@, @?|@ and @?&@
287+ let (h,t) = breakOnSingleQuestionMark s
194− split s = fromByteString h : if B.null t then [] else split (B.tail t)
291+ else split (B.tail t)
195− where (h,t) = B.break (=='?') s
196− zipParams (t:ts) (p:ps) = t `mappend` p `mappend` zipParams ts ps
292+ zipParams (t:ts) (p:ps) = t <> p <> zipParams ts ps
197 zipParams [t] [] = t
293 zipParams [t] [] = t
198− zipParams _ _ = fmtError (show (B.count '?' template) ++
294+ zipParams _ _ = fmtError (show countSingleQs ++
199− " '?' characters, but " ++
295+ " single '?' characters, but " ++
200 show (length xs) ++ " parameters") q xs
296 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
303+ where qms = B.splitAt 1 qmBS
304+ (qmBS,nextQMBS) = B.splitAt 2 qmBS'
305+ qmBS' = B.dropWhile (/= '?') bs
202-- | Execute an @INSERT@, @UPDATE@, or other SQL query that is not
307-- | Execute an @INSERT@, @UPDATE@, or other SQL query that is not
203-- expected to return results.
308-- expected to return results.
205-- Returns the number of rows affected.
310-- Returns the number of rows affected.
207−-- Throws 'FormatError' if the query could not be formatted correctly.
312+-- Throws 'FormatError' if the query could not be formatted correctly, or
313+-- a 'SqlError' exception if the backend returns an error.
208−execute :: (QueryParams q) => Connection -> Query -> q -> IO Int64
314+execute :: (ToRow q) => Connection -> Query -> q -> IO Int64
209execute conn template qs = do
315execute conn template qs = do
210 result <- exec conn =<< formatQuery conn template qs
316 result <- exec conn =<< formatQuery conn template qs
211 finishExecute conn template result
317 finishExecute conn template result
213−-- | A version of 'execute' that does not perform query substitution.
214−execute_ :: Connection -> Query -> IO Int64
215−execute_ conn q@(Query stmt) = do
216− result <- exec conn stmt
217− finishExecute conn q result
219-- | Execute a multi-row @INSERT@, @UPDATE@, or other SQL query that is not
319-- | Execute a multi-row @INSERT@, @UPDATE@, or other SQL query that is not
220-- expected to return results.
320-- expected to return results.
222−-- Returns the number of rows affected.
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.
224−-- Throws 'FormatError' if the query could not be formatted correctly.
326+-- Throws 'FormatError' if the query could not be formatted correctly, or
327+-- a 'SqlError' exception if the backend returns an error.
329+-- For example, here's a command that inserts two rows into a table
333+-- executeMany c [sql|
334+-- INSERT INTO sometable VALUES (?,?)
335+-- |] [(1, \"hello\"),(2, \"world\")]
338+-- Here's an canonical example of a multi-row update command:
341+-- executeMany c [sql|
344+-- FROM (VALUES (?,?)) as upd(x,y)
345+-- WHERE sometable.x = upd.x
346+-- |] [(1, \"hello\"),(2, \"world\")]
225−executeMany :: (QueryParams q) => Connection -> Query -> [q] -> IO Int64
349+executeMany :: (ToRow q) => Connection -> Query -> [q] -> IO Int64
226executeMany _ _ [] = return 0
350executeMany _ _ [] = return 0
227executeMany conn q qs = do
351executeMany conn q qs = do
228 result <- exec conn =<< formatMany conn q qs
352 result <- exec conn =<< formatMany conn q qs
229 finishExecute conn q result
353 finishExecute conn q result
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'.
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.
366+-- Throws 'FormatError' if the query could not be formatted correctly.
231−finishExecute :: Connection -> Query -> PQ.Result -> IO Int64
367+returning :: (ToRow q, FromRow r) => Connection -> Query -> [q] -> IO [r]
232−finishExecute conn q result = do
368+returning = returningWith fromRow
233− status <- PQ.resultStatus result
235− PQ.EmptyQuery -> fail "empty query" -- FIXME: error message
237− ncols <- PQ.nfields result
239− then throwIO $ QueryError ("execute resulted in " ++ show ncols ++
242− nstr <- PQ.cmdTuples result
243− return $ case nstr of
244− Nothing -> 0 -- is this appropriate?
245− Just str -> toInteger str
247− ncols <- PQ.nfields result
248− throwIO $ QueryError ("execute resulted in " ++ show ncols ++
250− PQ.CopyIn -> fail "FIXME: postgresql-simple does not currently support COPY IN"
251− PQ.CopyOut -> fail "FIXME: postgresql-simple does not currently support COPY OUT"
253− errormsg <- maybe "" id <$> PQ.resultErrorMessage result
254− statusmsg <- PQ.resStatus status
255− state <- maybe "" id <$> PQ.resultErrorField result PQ.DiagSqlstate
256− throw $ SqlError { sqlState = state
257− , sqlNativeError = 0 -- FIXME
258− , sqlErrorMsg = B.concat [ "execute: ", statusmsg
261− toInteger str = B.foldl' delta 0 str
264− if '0' <= c && c <= '9'
265− then 10 * acc + fromIntegral (ord c - ord '0')
266− else error ("finishExecute: not an int: " ++ B.unpack str)
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
270-- | Perform a @SELECT@ or other SQL query that is expected to return
377-- | Perform a @SELECT@ or other SQL query that is expected to return
271-- results. All results are retrieved and converted before this
378-- results. All results are retrieved and converted before this
@@ -282,33 +389,44 @@ finishExecute conn q result = do
282-- using 'execute' instead of 'query').
389-- using 'execute' instead of 'query').
284-- * 'ResultError': result conversion failed.
391-- * 'ResultError': result conversion failed.
285−query :: (QueryParams q, QueryResults r)
392+--
393+-- * 'SqlError': the postgresql backend returned an error, e.g.
394+-- a syntax or type error, or an incorrect table or column name.
286− => Connection -> Query -> q -> IO [r]
395+query :: (ToRow q, FromRow r) => Connection -> Query -> q -> IO [r]
287−query conn template qs = do
396+query = queryWith fromRow
288− result <- exec conn =<< formatQuery conn template qs
289− finishQuery conn template result
291-- | A version of 'query' that does not perform query substitution.
398-- | A version of 'query' that does not perform query substitution.
292−query_ :: (QueryResults r) => Connection -> Query -> IO [r]
399+query_ :: (FromRow r) => Connection -> Query -> IO [r]
400+query_ = queryWith_ fromRow
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
405+ result <- exec conn =<< formatQuery conn template qs
406+ finishQueryWith parser conn template result
408+-- | A version of 'query_' taking parser as argument
409+queryWith_ :: RowParser r -> Connection -> Query -> IO [r]
293−query_ conn q@(Query que) = do
410+queryWith_ parser conn q@(Query que) = do
294 result <- exec conn que
411 result <- exec conn que
295− finishQuery conn q result
412+ finishQueryWith parser conn q result
297-- | Perform a @SELECT@ or other SQL query that is expected to return
414-- | Perform a @SELECT@ or other SQL query that is expected to return
298-- results. Results are streamed incrementally from the server, and
415-- results. Results are streamed incrementally from the server, and
299-- consumed via a left fold.
416-- consumed via a left fold.
301−-- The result consumer must be carefully written to execute
302−-- quickly. If the consumer is slow, server resources will be tied up,
303−-- and other clients may not be able to update the tables from which
304−-- the results are being streamed.
306-- When dealing with small results, it may be simpler (and perhaps
418-- When dealing with small results, it may be simpler (and perhaps
307-- faster) to use 'query' instead.
419-- faster) to use 'query' instead.
309-- This fold is /not/ strict. The stream consumer is responsible for
421-- This fold is /not/ strict. The stream consumer is responsible for
310-- forcing the evaluation of its result to avoid space leaks.
422-- forcing the evaluation of its result to avoid space leaks.
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.
312-- Exceptions that may be thrown:
430-- Exceptions that may be thrown:
314-- * 'FormatError': the query string could not be formatted correctly.
432-- * 'FormatError': the query string could not be formatted correctly.
@@ -317,164 +435,202 @@ query_ conn q@(Query que) = do
317-- using 'execute' instead of 'query').
435-- using 'execute' instead of 'query').
319-- * 'ResultError': result conversion failed.
437-- * 'ResultError': result conversion failed.
320−fold :: (QueryParams q, QueryResults r) =>
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 )
446+ -> (a -> row -> IO a)
448+fold = foldWithOptions defaultFoldOptions
450+-- | A version of 'fold' taking a parser as an argument
451+foldWith :: ( ToRow params )
457+ -> (a -> row -> IO a)
459+foldWith = foldWithOptionsAndParser defaultFoldOptions
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.
470+ fetchQuantity :: !FetchQuantity,
471+ transactionMode :: !TransactionMode
474+-- | defaults to 'Automatic', and 'TransactionMode' 'ReadCommitted' 'ReadOnly'
475+defaultFoldOptions :: FoldOptions
476+defaultFoldOptions = FoldOptions {
477+ fetchQuantity = Automatic,
478+ transactionMode = TransactionMode ReadCommitted ReadOnly
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 )
321− Connection
489+ -> Connection
322− -> Query -- ^ Query template.
490+ -> Query
323− -> q -- ^ Query parameters.
491+ -> params
324− -> a -- ^ Initial state for result consumer.
492+ -> a
325− -> (a -> r -> IO a) -- ^ Result consumer.
493+ -> (a -> row -> IO a)
495+foldWithOptions opts = foldWithOptionsAndParser opts fromRow
497+-- | A version of 'foldWithOptions' taking a parser as an argument
498+foldWithOptionsAndParser :: (ToRow params)
505+ -> (a -> row -> IO a)
327−fold conn template qs z f = do
507+foldWithOptionsAndParser opts parser conn template qs a f = do
328− Base.query conn =<< formatQuery conn template qs
508+ q <- formatQuery conn template qs
329− finishFold conn template z f
509+ doFold opts parser conn template (Query q) a f
332-- | A version of 'fold' that does not perform query substitution.
511-- | A version of 'fold' that does not perform query substitution.
333−fold_ :: (QueryResults r) =>
512+fold_ :: (FromRow r) =>
334 Connection
513 Connection
335 -> Query -- ^ Query.
514 -> Query -- ^ Query.
336 -> a -- ^ Initial state for result consumer.
515 -> a -- ^ Initial state for result consumer.
337 -> (a -> r -> IO a) -- ^ Result consumer.
516 -> (a -> r -> IO a) -- ^ Result consumer.
339−fold_ conn q@(Query que) z f = do
518+fold_ = foldWithOptions_ defaultFoldOptions
340− Base.query conn que
519+
341− finishFold conn q z f
520+-- | A version of 'fold_' taking a parser as an argument
342−--}
521+foldWith_ :: RowParser r
343−{--
522+ -> Connection
527+foldWith_ = foldWithOptionsAndParser_ defaultFoldOptions
529+foldWithOptions_ :: (FromRow r) =>
532+ -> Query -- ^ Query.
533+ -> a -- ^ Initial state for result consumer.
534+ -> (a -> r -> IO a) -- ^ Result consumer.
536+foldWithOptions_ opts conn query' a f = doFold opts fromRow conn query' query' a f
538+-- | A version of 'foldWithOptions_' taking a parser as an argument
539+foldWithOptionsAndParser_ :: FoldOptions
542+ -> Query -- ^ Query.
543+ -> a -- ^ Initial state for result consumer.
544+ -> (a -> r -> IO a) -- ^ Result consumer.
546+foldWithOptionsAndParser_ opts parser conn query' a f = doFold opts parser conn query' query' a f
548+doFold :: FoldOptions
554+ -> (a -> row -> IO a)
556+doFold FoldOptions{..} parser conn _template q a0 f = do
557+ stat <- withConnection conn PQ.transactionStatus
559+ PQ.TransIdle -> withTransactionMode transactionMode conn go
560+ PQ.TransInTrans -> go
561+ PQ.TransActive -> fail "foldWithOpts FIXME: PQ.TransActive"
562+ -- This _shouldn't_ occur in the current incarnation of
563+ -- the library, as we aren't using libpq asynchronously.
564+ -- However, it could occur in future incarnations of
565+ -- this library or if client code uses the Internal module
566+ -- to use raw libpq commands on postgresql-simple connections.
567+ PQ.TransInError -> fail "foldWithOpts FIXME: PQ.TransInError"
568+ -- This should be turned into a better error message.
569+ -- It is probably a bad idea to automatically roll
570+ -- back the transaction and start another.
571+ PQ.TransUnknown -> fail "foldWithOpts FIXME: PQ.TransUnknown"
572+ -- Not sure what this means.
575+ declareCursor conn q
577+ foldForwardWithParser cursor parser chunkSize f a
579+ go = bracket declare closeCursor $ \cursor ->
580+ let loop a = fetch cursor a >>=
586+-- FIXME: choose the Automatic chunkSize more intelligently
587+-- One possibility is to use the type of the results, although this
588+-- still isn't a perfect solution, given that common types (e.g. text)
589+-- are of highly variable size.
590+-- A refinement of this technique is to pick this number adaptively
591+-- as results are read in from the database.
592+ chunkSize = case fetchQuantity of
344-- | A version of 'fold' that does not transform a state value.
596-- | A version of 'fold' that does not transform a state value.
345−forEach :: (QueryParams q, QueryResults r) =>
597+forEach :: (ToRow q, FromRow r) =>
346 Connection
598 Connection
347 -> Query -- ^ Query template.
599 -> Query -- ^ Query template.
348 -> q -- ^ Query parameters.
600 -> q -- ^ Query parameters.
349 -> (r -> IO ()) -- ^ Result consumer.
601 -> (r -> IO ()) -- ^ Result consumer.
351−forEach conn template qs = fold conn template qs () . const
603+forEach = forEachWith fromRow
352{-# INLINE forEach #-}
604{-# INLINE forEach #-}
606+-- | A version of 'forEach' taking a parser as an argument
607+forEachWith :: ( ToRow q )
614+forEachWith parser conn template qs = foldWith parser conn template qs () . const
615+{-# INLINE forEachWith #-}
354-- | A version of 'forEach' that does not perform query substitution.
617-- | A version of 'forEach' that does not perform query substitution.
355−forEach_ :: (QueryResults r) =>
618+forEach_ :: (FromRow r) =>
356 Connection
619 Connection
357 -> Query -- ^ Query template.
620 -> Query -- ^ Query template.
358 -> (r -> IO ()) -- ^ Result consumer.
621 -> (r -> IO ()) -- ^ Result consumer.
360−forEach_ conn template = fold_ conn template () . const
623+forEach_ = forEachWith_ fromRow
361{-# INLINE forEach_ #-}
624{-# INLINE forEach_ #-}
364−forM' :: (Ord n, Num n) => n -> n -> (n -> IO a) -> IO [a]
626+forEachWith_ :: RowParser r
365−forM' lo hi m = loop hi []
368− | n < lo = return as
373−finishQuery :: (QueryResults r) => Connection -> Query -> PQ.Result -> IO [r]
374−finishQuery conn q result = do
375− status <- PQ.resultStatus result
377− PQ.EmptyQuery -> fail "empty query" -- FIXME: error message
379− throwIO $ QueryError "query resulted in a command response" q
381− ncols <- PQ.nfields result
382− fields <- forM' 0 (ncols-1) $ \column -> do
383− type_oid <- PQ.ftype result column
384− typename <- getTypename conn type_oid
386− nrows <- PQ.ntuples result
387− forM' 0 (nrows-1) $ \row -> do
388− values <- forM' 0 (ncols-1) (\col -> PQ.getvalue' result row col)
389− case convertResults fields values of
390− Left err -> throwIO err
392− PQ.CopyIn -> fail "FIXME: postgresql-simple does not currently support COPY IN"
393− PQ.CopyOut -> fail "FIXME: postgresql-simple does not currently support COPY OUT"
395− errormsg <- maybe "" id <$> PQ.resultErrorMessage result
396− statusmsg <- PQ.resStatus status
397− state <- maybe "" id <$> PQ.resultErrorField result PQ.DiagSqlstate
398− throw $ SqlError { sqlState = state
399− , sqlNativeError = 0 -- FIXME
400− , sqlErrorMsg = B.concat [ "execute: ", statusmsg
404−withResult (Base.storeResult conn) q $ \r fs -> do
406−/ flip fix [] $ \loop acc -> do
407− row <- Base.fetchRow r
409− [] -> return (reverse acc)
410− _ -> let !c = convertResults fs row
414−finishFold :: (QueryResults r) =>
415− Connection -> Query -> a -> (a -> r -> IO a) -> IO a
416−finishFold conn q z0 f = withResult (Base.useResult conn) q $ \r fs ->
417− flip fix z0 $ \loop z -> do
418− row <- Base.fetchRow r
421− _ -> (f z $! convertResults fs row) >>= loop
424−withResult :: (IO Result) -> Query -> (Result -> [Field] -> IO a) -> IO a
425−withResult fetchResult q act = bracket fetchResult Base.freeResult $ \r -> do
426− ncols <- Base.fieldCount (Right r)
428− then throwIO $ QueryError "query resulted in zero-column result" q
429− else act r =<< Base.fetchFields r
431−-- | Execute an action inside a SQL transaction.
433−-- This function initiates a transaction with a \"@begin
434−-- transaction@\" statement, then executes the supplied action. If
435−-- the action succeeds, the transaction will be completed with
436−-- 'Base.commit' before this function returns.
438−-- If the action throws /any/ kind of exception (not just a
439−-- MySQL-related exception), the transaction will be rolled back using
440−-- 'Base.rollback', then the exception will be rethrown.
441−withTransaction :: Connection -> IO a -> IO a
442−withTransaction conn act = do
444− r <- act `onException` rollback conn
448−-- | Rollback a transaction.
449−-- rollback :: (MonadCatchIO m,MonadIO m) => Connection -> m ()
450−rollback :: Connection -> IO ()
452− _ <- execute_ conn "ABORT;"
455−-- | Commit a transaction.
456−-- commit :: (MonadCatchIO m,MonadIO m) => Connection -> m ()
627+ -> Connection
457−commit :: Connection -> IO ()
628+ -> Query
458−commit conn = do
629+ -> (r -> IO ())
459− _ <- execute_ conn "COMMIT;"
630+ -> IO ()
460− return ()
631+forEachWith_ parser conn template = foldWith_ parser conn template () . const
461−
632+{-# INLINE forEachWith_ #-}
462−-- | Begin a transaction.
633+
463−-- begin :: (MonadCatchIO m,MonadIO m) => Connection -> m ()
464−begin :: Connection -> IO ()
466− _ <- execute_ conn "BEGIN;"
469−fmtError :: String -> Query -> [Action] -> a
470−fmtError msg q xs = throw FormatError {
473− , fmtParams = map twiddle xs
475− where twiddle (Plain b) = toByteString b
476− twiddle (Escape s) = s
477− twiddle (Many ys) = B.concat (map twiddle ys)
@@ -500,11 +656,13 @@ fmtError msg q xs = throw FormatError {
501-- > {-# LANGUAGE OverloadedStrings #-}
657-- > {-# LANGUAGE OverloadedStrings #-}
503−-- > import Database.MySQL.Simple
659+-- > import Database.PostgreSQL.Simple
505-- > hello = do
662-- > hello = do
506−-- > conn <- connect defaultConnectInfo
663+-- > conn <- connectPostgreSQL ""
507−-- > query conn "select 2 + 2"
664+-- > [Only i] <- query_ conn "select 2 + 2"
509-- A 'Query' value does not represent the actual query that will be
667-- A 'Query' value does not represent the actual query that will be
510-- executed, but is a template for constructing the final query.
668-- executed, but is a template for constructing the final query.
@@ -551,7 +709,7 @@ fmtError msg q xs = throw FormatError {
551-- Automated type inference means that you will often be able to avoid
709-- Automated type inference means that you will often be able to avoid
552-- supplying explicit type signatures for the elements of a tuple.
710-- supplying explicit type signatures for the elements of a tuple.
553-- However, sometimes the compiler will not be able to infer your
711-- However, sometimes the compiler will not be able to infer your
554−-- types. Consider a care where you write a numeric literal in a
712+-- types. Consider a case where you write a numeric literal in a
555-- parameter tuple:
713-- parameter tuple:
557-- > query conn "select ? + ?" (40,2)
715-- > query conn "select ? + ?" (40,2)
@@ -565,15 +723,30 @@ fmtError msg q xs = throw FormatError {
565-- The same kind of problem can arise with string literals if you have
723-- The same kind of problem can arise with string literals if you have
566-- the @OverloadedStrings@ language extension enabled. Again, just
724-- the @OverloadedStrings@ language extension enabled. Again, just
567-- use an explicit type signature if this happens.
725-- use an explicit type signature if this happens.
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:
731+-- > print =<< query_ conn "select 2 + 2"
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:
738+-- > xs <- query_ conn "select 2 + 2"
739+-- > print (xs :: [Only Int])
569-- $only_param
741-- $only_param
571-- Haskell lacks a single-element tuple type, so if you have just one
743-- Haskell lacks a single-element tuple type, so if you have just one
572−-- value you want substituted into a query, what should you do?
744+-- value you want substituted into a query or a single-column result,
745+-- what should you do?
574-- The obvious approach would appear to be something like this:
747-- The obvious approach would appear to be something like this:
576−-- > instance (Param a) => QueryParam a where
749+-- > instance (ToField a) => ToRow a where
579-- Unfortunately, this wreaks havoc with type inference, so we take a
752-- Unfortunately, this wreaks havoc with type inference, so we take a
@@ -584,6 +757,9 @@ fmtError msg q xs = throw FormatError {
585-- > execute conn "insert into users (first_name) values (?)"
758-- > execute conn "insert into users (first_name) values (?)"
586-- > ["Nuala"]
759-- > ["Nuala"]
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.
@@ -601,7 +777,7 @@ fmtError msg q xs = throw FormatError {
601-- Here's an example:
777-- Here's an example:
603-- > query conn "select * from users where first_name in ?" $
779-- > query conn "select * from users where first_name in ?" $
604−-- > In ["Anna", "Boris", "Carla"]
780+-- > Only $ In ["Anna", "Boris", "Carla"]
606-- If your 'In'-wrapped list is empty, the string @\"(null)\"@ will be
782-- If your 'In'-wrapped list is empty, the string @\"(null)\"@ will be
607-- substituted instead, to ensure that your clause remains
783-- substituted instead, to ensure that your clause remains
@@ -629,7 +805,7 @@ fmtError msg q xs = throw FormatError {
629-- * There must be no other \"@?@\" characters anywhere in your
805-- * There must be no other \"@?@\" characters anywhere in your
630-- template.
806-- template.
632−-- * There must one or more \"@?@\" in the parentheses.
808+-- * There must be one or more \"@?@\" in the parentheses.
634-- * Extra white space is fine.
810-- * Extra white space is fine.
@@ -650,10 +826,26 @@ fmtError msg q xs = throw FormatError {
650-- > insert into users (first_name,last_name) values
826-- > insert into users (first_name,last_name) values
651-- > ('Boris','Karloff'),('Ed','Wood')
827-- > ('Boris','Karloff'),('Ed','Wood')
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'.
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.
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")]
653-- $result
845-- $result
655-- The 'query' and 'query_' functions return a list of values in the
847-- The 'query' and 'query_' functions return a list of values in the
656−-- 'QueryResults' typeclass. This class performs automatic extraction
848+-- 'FromRow' typeclass. This class performs automatic extraction
657-- and type conversion of rows from a query result.
849-- and type conversion of rows from a query result.
659-- Here is a simple example of how to extract results:
851-- Here is a simple example of how to extract results:
@@ -684,7 +876,7 @@ fmtError msg q xs = throw FormatError {
685-- Although SQL can accommodate @NULL@ as a value for any of these
877-- Although SQL can accommodate @NULL@ as a value for any of these
686-- types, Haskell cannot. If your result contains columns that may be
878-- types, Haskell cannot. If your result contains columns that may be
687−-- @NULL@, be sure that you use 'Maybe' in those positions of of your
879+-- @NULL@, be sure that you use 'Maybe' in those positions of your
690-- > (Text, Maybe Int, Int)
882-- > (Text, Maybe Int, Int)
@@ -707,16 +899,15 @@ fmtError msg q xs = throw FormatError {
707-- permissive. Here are the rules.
899-- permissive. Here are the rules.
709-- * For numeric types, any Haskell type that can accurately represent
901-- * For numeric types, any Haskell type that can accurately represent
710−-- all values of the given MySQL type is considered \"compatible\".
902+-- all values of the given PostgreSQL type is considered \"compatible\".
711−-- For instance, you can always extract a MySQL @TINYINT@ column to
903+-- For instance, you can always extract a PostgreSQL 16-bit @SMALLINT@
712−-- a Haskell 'Int'. The Haskell 'Float' type can accurately
904+-- column to a Haskell 'Int'. The Haskell 'Float' type can accurately
713−-- represent MySQL integer types of size up to @INT24@, so it is
714−-- considered compatble with those types.
905+-- represent a @SMALLINT@, so it is considered compatible with those types.
716-- * A numeric compatibility check is based only on the type of a
907-- * A numeric compatibility check is based only on the type of a
717−-- column, /not/ on its values. For instance, a MySQL @LONG_LONG@
908+-- column, /not/ on its values. For instance, a PostgreSQL 64-bit
718−-- column will be considered incompatible with a Haskell 'Int8',
909+-- @BIGINT@ column will be considered incompatible with a Haskell
719−-- even if it contains the value @1@.
910+-- 'Int16', even if it contains the value @1@.
721-- * If a numeric incompatibility is found, 'query' will throw a
912-- * If a numeric incompatibility is found, 'query' will throw a
722-- 'ResultError'.
913-- 'ResultError'.
@@ -725,29 +916,3 @@ fmtError msg q xs = throw FormatError {
725-- UTF-8. If you use some other encoding, decoding may fail or give
916-- UTF-8. If you use some other encoding, decoding may fail or give
726-- wrong results. In such cases, write a @newtype@ wrapper and a
917-- wrong results. In such cases, write a @newtype@ wrapper and a
727-- custom 'Result' instance to handle your encoding.
918-- custom 'Result' instance to handle your encoding.
729−getTypename :: Connection -> PQ.Oid -> IO ByteString
730−getTypename conn@Connection{..} oid =
731− case oid2builtin oid of
732− Just builtin -> return $! builtin2typname builtin
734− oidmap <- takeMVar connectionObjects
735− case IntMap.lookup (oid2int oid) oidmap of
736− Just name -> putMVar connectionObjects oidmap >> return name
738− names <- query conn "SELECT typname FROM pg_type WHERE oid=?"
740− name <- case names of
741− [] -> return $ throw SqlError {
742− sqlNativeError = -1,
743− sqlErrorMsg = "invalid type oid",
746− [Only x] -> return x
747− _ -> fail "typename query returned more than one result"
748− -- oid is a primary key, so the query should
749− -- never return more than one result
750− putMVar connectionObjects (IntMap.insert (oid2int oid) name oidmap)
753− putMVar connectionObjects oidmap