module Database.Persist.Postgresql
( withPostgresqlPool
, withPostgresqlConn
, createPostgresqlPool
, module Database.Persist.Sql
, ConnectionString
, PostgresConf (..)
, openSimpleConn
) where
import Database.Persist.Sql
import Data.Fixed (Pico)
import qualified Database.PostgreSQL.Simple as PG
import qualified Database.PostgreSQL.Simple.BuiltinTypes as PG
import qualified Database.PostgreSQL.Simple.Internal as PG
import qualified Database.PostgreSQL.Simple.ToField as PGTF
import qualified Database.PostgreSQL.Simple.FromField as PGFF
import qualified Database.PostgreSQL.Simple.Types as PG
import Database.PostgreSQL.Simple.Ok (Ok (..))
import qualified Database.PostgreSQL.LibPQ as LibPQ
import Control.Exception (throw)
import Control.Monad.IO.Class (MonadIO (..))
import Data.Typeable
import Data.IORef
import qualified Data.Map as Map
import Data.Either (partitionEithers)
import Control.Arrow
import Data.List (find, intercalate, sort, groupBy)
import Data.Function (on)
import Data.Conduit
import qualified Data.Conduit.List as CL
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as B8
import qualified Data.Text as T
import qualified Data.Text.Encoding as T
import qualified Blaze.ByteString.Builder.Char8 as BBB
import qualified Blaze.ByteString.Builder.ByteString as BBS
import Data.Time.LocalTime (localTimeToUTC, utc)
import Data.Text (Text)
import Data.Aeson
import Control.Monad (forM, mzero)
import System.Environment (getEnvironment)
import Data.Int (Int64)
import Data.Maybe (mapMaybe, fromJust, isJust, fromMaybe)
import Data.Monoid ((<>))
type ConnectionString = ByteString
withPostgresqlPool :: MonadIO m
=> ConnectionString
-> Int
-> (ConnectionPool -> m a)
-> m a
withPostgresqlPool ci = withSqlPool $ open' ci
createPostgresqlPool :: MonadIO m
=> ConnectionString
-> Int
-> m ConnectionPool
createPostgresqlPool ci = createSqlPool $ open' ci
withPostgresqlConn :: (MonadIO m, MonadBaseControl IO m)
=> ConnectionString -> (Connection -> m a) -> m a
withPostgresqlConn = withSqlConn . open'
open' :: ConnectionString -> IO Connection
open' cstr = do
PG.connectPostgreSQL cstr >>= openSimpleConn
openSimpleConn :: PG.Connection -> IO Connection
openSimpleConn conn = do
smap <- newIORef $ Map.empty
return Connection
{ connPrepare = prepare' conn
, connStmtMap = smap
, connInsertSql = insertSql'
, connClose = PG.close conn
, connMigrateSql = migrate'
, connBegin = const $ PG.begin conn
, connCommit = const $ PG.commit conn
, connRollback = const $ PG.rollback conn
, connEscapeName = escape
, connNoLimit = "LIMIT ALL"
, connRDBMS = "postgresql"
, connLimitOffset = decorateSQLWithLimitOffset "LIMIT ALL"
}
prepare' :: PG.Connection -> Text -> IO Statement
prepare' conn sql = do
let query = PG.Query (T.encodeUtf8 sql)
return Statement
{ stmtFinalize = return ()
, stmtReset = return ()
, stmtExecute = execute' conn query
, stmtQuery = withStmt' conn query
}
insertSql' :: EntityDef SqlType -> [PersistValue] -> InsertSqlResult
insertSql' ent vals =
let sql = T.concat
[ "INSERT INTO "
, escape $ entityDB ent
, "("
, T.intercalate "," $ map (escape . fieldDB) $ entityFields ent
, ") VALUES("
, T.intercalate "," (map (const "?") $ entityFields ent)
, ")"
]
in case entityPrimary ent of
Just pdef -> ISRManyKeys sql vals
Nothing -> ISRSingle (sql <> " RETURNING " <> escape (entityID ent))
execute' :: PG.Connection -> PG.Query -> [PersistValue] -> IO Int64
execute' conn query vals = PG.execute conn query (map P vals)
withStmt' :: MonadResource m
=> PG.Connection
-> PG.Query
-> [PersistValue]
-> Source m [PersistValue]
withStmt' conn query vals =
bracketP openS closeS pull
where
openS = do
rawquery <- PG.formatQuery conn query (map P vals)
PG.withConnection conn $ \rawconn -> do
mret <- LibPQ.exec rawconn rawquery
case mret of
Nothing -> do
merr <- LibPQ.errorMessage rawconn
fail $ case merr of
Nothing -> "Postgresql.withStmt': unknown error"
Just e -> "Postgresql.withStmt': " ++ B8.unpack e
Just ret -> do
status <- LibPQ.resultStatus ret
case status of
LibPQ.TuplesOk -> return ()
_ -> do
msg <- LibPQ.resStatus status
mmsg <- LibPQ.resultErrorMessage ret
fail $ "Postgresql.withStmt': bad result status " ++
show status ++ " (" ++ (maybe (show msg) (show . (,) msg) mmsg) ++ ")"
cols <- LibPQ.nfields ret
getters <- forM [0..cols1] $ \col -> do
oid <- LibPQ.ftype ret col
case PG.oid2builtin oid of
Nothing -> return $ \bs->
case bs of
Nothing -> fail $ "Unexpected null value in backend specific value"
Just a -> return $ PersistDbSpecific a
Just bt -> return $ getGetter bt $
PG.Field ret col oid
rowRef <- newIORef (LibPQ.Row 0)
rowCount <- LibPQ.ntuples ret
return (ret, rowRef, rowCount, getters)
closeS (ret, _, _, _) = LibPQ.unsafeFreeResult ret
pull x = do
y <- liftIO $ pullS x
case y of
Nothing -> return ()
Just z -> yield z >> pull x
pullS (ret, rowRef, rowCount, getters) = do
row <- atomicModifyIORef rowRef (\r -> (r+1, r))
if row == rowCount
then return Nothing
else fmap Just $ forM (zip getters [0..]) $ \(getter, col) -> do
mbs <- LibPQ.getvalue' ret row col
case mbs of
Nothing -> return PersistNull
Just bs -> do
ok <- PGFF.runConversion (getter mbs) conn
bs `seq` case ok of
Errors (exc:_) -> throw exc
Errors [] -> error "Got an Errors, but no exceptions"
Ok v -> return v
newtype P = P PersistValue
instance PGTF.ToField P where
toField (P (PersistText t)) = PGTF.toField t
toField (P (PersistByteString bs)) = PGTF.toField (PG.Binary bs)
toField (P (PersistInt64 i)) = PGTF.toField i
toField (P (PersistDouble d)) = PGTF.toField d
toField (P (PersistRational r)) = PGTF.Plain $
BBB.fromString $
show (fromRational r :: Pico)
toField (P (PersistBool b)) = PGTF.toField b
toField (P (PersistDay d)) = PGTF.toField d
toField (P (PersistTimeOfDay t)) = PGTF.toField t
toField (P (PersistUTCTime t)) = PGTF.toField t
toField (P (PersistZonedTime (ZT t))) = PGTF.toField t
toField (P PersistNull) = PGTF.toField PG.Null
toField (P (PersistList l)) = PGTF.toField $ listToJSON l
toField (P (PersistMap m)) = PGTF.toField $ mapToJSON m
toField (P (PersistDbSpecific s)) = PGTF.toField (Unknown s)
toField (P (PersistObjectId _)) =
error "Refusing to serialize a PersistObjectId to a PostgreSQL value"
newtype Unknown = Unknown { unUnknown :: ByteString }
deriving (Eq, Show, Read, Ord, Typeable)
instance PGFF.FromField Unknown where
fromField f mdata =
case mdata of
Nothing -> PGFF.returnError PGFF.UnexpectedNull f ""
Just dat -> return (Unknown dat)
instance PGTF.ToField Unknown where
toField (Unknown a) = PGTF.Escape a
type Getter a = PGFF.FieldParser a
convertPV :: PGFF.FromField a => (a -> b) -> Getter b
convertPV f = (fmap f .) . PGFF.fromField
getGetter :: PG.BuiltinType -> Getter PersistValue
getGetter PG.Bool = convertPV PersistBool
getGetter PG.ByteA = convertPV (PersistByteString . unBinary)
getGetter PG.Char = convertPV PersistText
getGetter PG.Name = convertPV PersistText
getGetter PG.Int8 = convertPV PersistInt64
getGetter PG.Int2 = convertPV PersistInt64
getGetter PG.Int4 = convertPV PersistInt64
getGetter PG.Text = convertPV PersistText
getGetter PG.Xml = convertPV PersistText
getGetter PG.Float4 = convertPV PersistDouble
getGetter PG.Float8 = convertPV PersistDouble
getGetter PG.AbsTime = convertPV PersistUTCTime
getGetter PG.RelTime = convertPV PersistUTCTime
getGetter PG.Money = convertPV PersistDouble
getGetter PG.BpChar = convertPV PersistText
getGetter PG.VarChar = convertPV PersistText
getGetter PG.Date = convertPV PersistDay
getGetter PG.Time = convertPV PersistTimeOfDay
getGetter PG.Timestamp = convertPV (PersistUTCTime . localTimeToUTC utc)
getGetter PG.TimestampTZ = convertPV (PersistZonedTime . ZT)
getGetter PG.Bit = convertPV PersistInt64
getGetter PG.VarBit = convertPV PersistInt64
getGetter PG.Numeric = convertPV PersistRational
getGetter PG.Void = \_ _ -> return PersistNull
getGetter PG.UUID = convertPV (PersistDbSpecific . unUnknown)
getGetter other = error $ "Postgresql.getGetter: type " ++
show other ++ " not supported."
unBinary :: PG.Binary a -> a
unBinary (PG.Binary x) = x
doesTableExist :: (Text -> IO Statement)
-> DBName
-> IO Bool
doesTableExist getter (DBName name) = do
stmt <- getter sql
runResourceT $ stmtQuery stmt vals $$ start
where
sql = "SELECT COUNT(*) FROM information_schema.tables WHERE table_name=?"
vals = [PersistText name]
start = await >>= maybe (error "No results when checking doesTableExist") start'
start' [PersistInt64 0] = finish False
start' [PersistInt64 1] = finish True
start' res = error $ "doesTableExist returned unexpected result: " ++ show res
finish x = await >>= maybe (return x) (error "Too many rows returned in doesTableExist")
migrate' :: [EntityDef a]
-> (Text -> IO Statement)
-> EntityDef SqlType
-> IO (Either [Text] [(Bool, Text)])
migrate' allDefs getter val = fmap (fmap $ map showAlterDb) $ do
let name = entityDB val
old <- getColumns getter val
case partitionEithers old of
([], old'') -> do
let old' = partitionEithers old''
let (newcols', udefs, fdefs) = mkColumns allDefs val
let newcols = filter (not . safeToRemove val . cName) newcols'
let udspair = map udToPair udefs
exists <-
if null old
then doesTableExist getter name
else return True
if not exists
then do
let idtxt = case entityPrimary val of
Just pdef -> T.concat [" PRIMARY KEY (", T.intercalate "," $ map (escape . snd) $ primaryFields pdef, ")"]
Nothing -> T.concat [escape $ entityID val
, " SERIAL PRIMARY KEY UNIQUE"]
let addTable = AddTable $ T.concat
[ "CREATe TABLE "
, escape name
, "("
, idtxt
, if null newcols then "" else ","
, T.intercalate "," $ map showColumn newcols
, ")"
]
let uniques = flip concatMap udspair $ \(uname, ucols) ->
[AlterTable name $ AddUniqueConstraint uname ucols]
references = mapMaybe (\c@Column { cName=cname, cReference=Just (refTblName, _) } -> getAddReference allDefs name refTblName cname (cReference c)) $ filter (\c -> cReference c /= Nothing) newcols
foreignsAlt = map (\fdef -> let (childfields, parentfields) = unzip (map (\(_,b,_,d) -> (b,d)) (foreignFields fdef))
in AlterColumn name (foreignRefTableDBName fdef, AddReference (foreignConstraintNameDBName fdef) childfields parentfields)) fdefs
return $ Right $ addTable : uniques ++ references ++ foreignsAlt
else do
let (acs, ats) = getAlters allDefs val (newcols, udspair) old'
let acs' = map (AlterColumn name) acs
let ats' = map (AlterTable name) ats
return $ Right $ acs' ++ ats'
(errs, _) -> return $ Left errs
type SafeToRemove = Bool
data AlterColumn = Type SqlType | IsNull | NotNull | Add' Column | Drop SafeToRemove
| Default Text | NoDefault | Update' Text
| AddReference DBName [DBName] [DBName] | DropReference DBName
type AlterColumn' = (DBName, AlterColumn)
data AlterTable = AddUniqueConstraint DBName [DBName]
| DropConstraint DBName
data AlterDB = AddTable Text
| AlterColumn DBName AlterColumn'
| AlterTable DBName AlterTable
getColumns :: (Text -> IO Statement)
-> EntityDef a
-> IO [Either Text (Either Column (DBName, [DBName]))]
getColumns getter def = do
let sqlv=T.concat ["SELECT "
,"column_name "
,",is_nullable "
,",udt_name "
,",column_default "
,",numeric_precision "
,",numeric_scale "
,"FROM information_schema.columns "
,"WHERE table_catalog=current_database() "
,"AND table_schema=current_schema() "
,"AND table_name=? "
,"AND column_name <> ?"]
stmt <- getter sqlv
let vals =
[ PersistText $ unDBName $ entityDB def
, PersistText $ unDBName $ entityID def
]
cs <- runResourceT $ stmtQuery stmt vals $$ helper
let sqlc = T.concat ["SELECT "
,"c.constraint_name, "
,"c.column_name "
,"FROM information_schema.key_column_usage c, "
,"information_schema.table_constraints k "
,"WHERE c.table_catalog=current_database() "
,"AND c.table_catalog=k.table_catalog "
,"AND c.table_schema=current_schema() "
,"AND c.table_schema=k.table_schema "
,"AND c.table_name=? "
,"AND c.table_name=k.table_name "
,"AND c.column_name <> ? "
,"AND c.constraint_name=k.constraint_name "
,"AND NOT k.constraint_type IN ('PRIMARY KEY', 'FOREIGN KEY') "
,"ORDER BY c.constraint_name, c.column_name"]
stmt' <- getter sqlc
us <- runResourceT $ stmtQuery stmt' vals $$ helperU
return $ cs ++ us
where
getAll front = do
x <- CL.head
case x of
Nothing -> return $ front []
Just [PersistText con, PersistText col] -> getAll (front . (:) (con, col))
Just [PersistByteString con, PersistByteString col] -> getAll (front . (:) (T.decodeUtf8 con, T.decodeUtf8 col))
Just o -> error $ "unexpected datatype returned for postgres o="++show o
helperU = do
rows <- getAll id
return $ map (Right . Right . (DBName . fst . head &&& map (DBName . snd)))
$ groupBy ((==) `on` fst) rows
helper = do
x <- CL.head
case x of
Nothing -> return []
Just x' -> do
col <- liftIO $ getColumn getter (entityDB def) x'
let col' = case col of
Left e -> Left e
Right c -> Right $ Left c
cols <- helper
return $ col' : cols
safeToRemove :: EntityDef a -> DBName -> Bool
safeToRemove def (DBName colName)
= any (elem "SafeToRemove" . fieldAttrs)
$ filter ((== (DBName colName)) . fieldDB)
$ entityFields def
getAlters :: [EntityDef a]
-> EntityDef SqlType
-> ([Column], [(DBName, [DBName])])
-> ([Column], [(DBName, [DBName])])
-> ([AlterColumn'], [AlterTable])
getAlters defs def (c1, u1) (c2, u2) =
(getAltersC c1 c2, getAltersU u1 u2)
where
getAltersC [] old = map (\x -> (cName x, Drop $ safeToRemove def $ cName x)) old
getAltersC (new:news) old =
let (alters, old') = findAlters defs (entityDB def) new old
in alters ++ getAltersC news old'
getAltersU :: [(DBName, [DBName])]
-> [(DBName, [DBName])]
-> [AlterTable]
getAltersU [] old = map DropConstraint $ filter (not . isManual) $ map fst old
getAltersU ((name, cols):news) old =
case lookup name old of
Nothing -> AddUniqueConstraint name cols : getAltersU news old
Just ocols ->
let old' = filter (\(x, _) -> x /= name) old
in if sort cols == sort ocols
then getAltersU news old'
else DropConstraint name
: AddUniqueConstraint name cols
: getAltersU news old'
isManual (DBName x) = "__manual_" `T.isPrefixOf` x
getColumn :: (Text -> IO Statement)
-> DBName -> [PersistValue]
-> IO (Either Text Column)
getColumn getter tname [PersistText x, PersistText y, PersistText z, d, npre, nscl] =
case d' of
Left s -> return $ Left s
Right d'' ->
case getType z of
Left s -> return $ Left s
Right t -> do
let cname = DBName x
ref <- getRef cname
return $ Right Column
{ cName = cname
, cNull = y == "YES"
, cSqlType = t
, cDefault = fmap
(\x -> fromMaybe x $ T.stripSuffix "::character varying" x)
d''
, cDefaultConstraintName = Nothing
, cMaxLen = Nothing
, cReference = ref
}
where
getRef cname = do
let sql = T.concat
[ "SELECT COUNT(*) FROM "
, "information_schema.table_constraints "
, "WHERE table_catalog=current_database() "
, "AND table_schema=current_schema() "
, "AND table_name=? "
, "AND constraint_type='FOREIGN KEY' "
, "AND constraint_name=?"
]
let ref = refName tname cname
stmt <- getter sql
runResourceT $ stmtQuery stmt
[ PersistText $ unDBName tname
, PersistText $ unDBName ref
] $$ do
Just [PersistInt64 i] <- CL.head
return $ if i == 0 then Nothing else Just (DBName "", ref)
d' = case d of
PersistNull -> Right Nothing
PersistText t -> Right $ Just t
_ -> Left $ T.pack $ "Invalid default column: " ++ show d
getType "int4" = Right $ SqlInt32
getType "int8" = Right $ SqlInt64
getType "varchar" = Right $ SqlString
getType "date" = Right $ SqlDay
getType "bool" = Right $ SqlBool
getType "timestamp" = Right $ SqlDayTime
getType "timestamptz" = Right $ SqlDayTimeZoned
getType "float4" = Right $ SqlReal
getType "float8" = Right $ SqlReal
getType "bytea" = Right $ SqlBlob
getType "time" = Right $ SqlTime
getType "numeric" = getNumeric npre nscl
getType a = Right $ SqlOther a
getNumeric (PersistInt64 a) (PersistInt64 b) = Right $ SqlNumeric (fromIntegral a) (fromIntegral b)
getNumeric a b = Left $ T.pack $ "Can not get numeric field precision, got: " ++ show a ++ " and " ++ show b ++ " as precision and scale"
getColumn _ _ x =
return $ Left $ T.pack $ "Invalid result from information_schema: " ++ show x
sqlTypeEq :: SqlType -> SqlType -> Bool
sqlTypeEq x y =
T.toCaseFold (showSqlType x) == T.toCaseFold (showSqlType y)
findAlters :: [EntityDef a] -> DBName -> Column -> [Column] -> ([AlterColumn'], [Column])
findAlters defs tablename col@(Column name isNull sqltype def defConstraintName _maxLen ref) cols =
case filter (\c -> cName c == name) cols of
[] -> ([(name, Add' col)], cols)
Column _ isNull' sqltype' def' defConstraintName' _maxLen' ref':_ ->
let refDrop Nothing = []
refDrop (Just (_, cname)) = [(name, DropReference cname)]
refAdd Nothing = []
refAdd (Just (tname, a)) = case find ((==tname) . entityDB) defs of
Just refdef -> [(tname, AddReference a [name] [entityID refdef])]
Nothing -> error $ "could not find the entityDef for reftable[" ++ show tname ++ "]"
modRef =
if fmap snd ref == fmap snd ref'
then []
else refDrop ref' ++ refAdd ref
modNull = case (isNull, isNull') of
(True, False) -> [(name, IsNull)]
(False, True) ->
let up = case def of
Nothing -> id
Just s -> (:) (name, Update' s)
in up [(name, NotNull)]
_ -> []
modType = if sqlTypeEq sqltype sqltype' then [] else [(name, Type sqltype)]
modDef =
if def == def'
then []
else case def of
Nothing -> [(name, NoDefault)]
Just s -> [(name, Default s)]
in (modRef ++ modDef ++ modNull ++ modType,
filter (\c -> cName c /= name) cols)
getAddReference :: [EntityDef a] -> DBName -> DBName -> DBName -> Maybe (DBName, DBName) -> Maybe AlterDB
getAddReference allDefs table reftable cname ref =
case ref of
Nothing -> Nothing
Just (s, z) -> Just $ AlterColumn table (s, AddReference (refName table cname) [cname] [id_])
where
id_ = maybe (error $ "Could not find ID of entity " ++ show reftable)
id $ do
entDef <- find ((== reftable) . entityDB) allDefs
return (entityID entDef)
showColumn :: Column -> Text
showColumn c@(Column n nu sqlType def defConstraintName _maxLen _ref) = T.concat
[ escape n
, " "
, showSqlType sqlType
, " "
, if nu then "NULL" else "NOT NULL"
, case def of
Nothing -> ""
Just s -> " DEFAULT " <> s
]
showSqlType :: SqlType -> Text
showSqlType SqlString = "VARCHAR"
showSqlType SqlInt32 = "INT4"
showSqlType SqlInt64 = "INT8"
showSqlType SqlReal = "DOUBLE PRECISION"
showSqlType (SqlNumeric s prec) = T.concat [ "NUMERIC(", T.pack (show s), ",", T.pack (show prec), ")" ]
showSqlType SqlDay = "DATE"
showSqlType SqlTime = "TIME"
showSqlType SqlDayTime = "TIMESTAMP"
showSqlType SqlDayTimeZoned = "TIMESTAMP WITH TIME ZONE"
showSqlType SqlBlob = "BYTEA"
showSqlType SqlBool = "BOOLEAN"
showSqlType (SqlOther (T.toLower -> "integer")) = "INT4"
showSqlType (SqlOther t) = t
showAlterDb :: AlterDB -> (Bool, Text)
showAlterDb (AddTable s) = (False, s)
showAlterDb (AlterColumn t (c, ac)) =
(isUnsafe ac, showAlter t (c, ac))
where
isUnsafe (Drop safeRemove) = not safeRemove
isUnsafe _ = False
showAlterDb (AlterTable t at) = (False, showAlterTable t at)
showAlterTable :: DBName -> AlterTable -> Text
showAlterTable table (AddUniqueConstraint cname cols) = T.concat
[ "ALTER TABLE "
, escape table
, " ADD CONSTRAINT "
, escape cname
, " UNIQUE("
, T.intercalate "," $ map escape cols
, ")"
]
showAlterTable table (DropConstraint cname) = T.concat
[ "ALTER TABLE "
, escape table
, " DROP CONSTRAINT "
, escape cname
]
showAlter :: DBName -> AlterColumn' -> Text
showAlter table (n, Type t) =
T.concat
[ "ALTER TABLE "
, escape table
, " ALTER COLUMN "
, escape n
, " TYPE "
, showSqlType t
]
showAlter table (n, IsNull) =
T.concat
[ "ALTER TABLE "
, escape table
, " ALTER COLUMN "
, escape n
, " DROP NOT NULL"
]
showAlter table (n, NotNull) =
T.concat
[ "ALTER TABLE "
, escape table
, " ALTER COLUMN "
, escape n
, " SET NOT NULL"
]
showAlter table (_, Add' col) =
T.concat
[ "ALTER TABLE "
, escape table
, " ADD COLUMN "
, showColumn col
]
showAlter table (n, Drop _) =
T.concat
[ "ALTER TABLE "
, escape table
, " DROP COLUMN "
, escape n
]
showAlter table (n, Default s) =
T.concat
[ "ALTER TABLE "
, escape table
, " ALTER COLUMN "
, escape n
, " SET DEFAULT "
, s
]
showAlter table (n, NoDefault) = T.concat
[ "ALTER TABLE "
, escape table
, " ALTER COLUMN "
, escape n
, " DROP DEFAULT"
]
showAlter table (n, Update' s) = T.concat
[ "UPDATE "
, escape table
, " SET "
, escape n
, "="
, s
, " WHERE "
, escape n
, " IS NULL"
]
showAlter table (reftable, AddReference fkeyname t2 id2) = T.concat
[ "ALTER TABLE "
, escape table
, " ADD CONSTRAINT "
, escape fkeyname
, " FOREIGN KEY("
, T.intercalate "," $ map escape t2
, ") REFERENCES "
, escape reftable
, "("
, T.intercalate "," $ map escape id2
, ")"
]
showAlter table (_, DropReference cname) = T.concat
[ "ALTER TABLE "
, escape table
, " DROP CONSTRAINT "
, escape cname
]
escape :: DBName -> Text
escape (DBName s) =
T.pack $ '"' : go (T.unpack s) ++ "\""
where
go "" = ""
go ('"':xs) = "\"\"" ++ go xs
go (x:xs) = x : go xs
data PostgresConf = PostgresConf
{ pgConnStr :: ConnectionString
, pgPoolSize :: Int
}
instance PersistConfig PostgresConf where
type PersistConfigBackend PostgresConf = SqlPersistT
type PersistConfigPool PostgresConf = ConnectionPool
createPoolConfig (PostgresConf cs size) = createPostgresqlPool cs size
runPool _ = runSqlPool
loadConfig (Object o) = do
database <- o .: "database"
host <- o .: "host"
port <- o .:? "port" .!= 5432
user <- o .: "user"
password <- o .: "password"
pool <- o .: "poolsize"
let ci = PG.ConnectInfo
{ PG.connectHost = host
, PG.connectPort = port
, PG.connectUser = user
, PG.connectPassword = password
, PG.connectDatabase = database
}
cstr = PG.postgreSQLConnectionString ci
return $ PostgresConf cstr pool
loadConfig _ = mzero
applyEnv c0 = do
env <- getEnvironment
return $ addUser env
$ addPass env
$ addDatabase env
$ addPort env
$ addHost env c0
where
addParam param val c =
c { pgConnStr = B8.concat [pgConnStr c, " ", param, "='", pgescape val, "'"] }
pgescape = B8.pack . go
where
go ('\'':rest) = '\\' : '\'' : go rest
go ('\\':rest) = '\\' : '\\' : go rest
go ( x :rest) = x : go rest
go [] = []
maybeAddParam param envvar env =
maybe id (addParam param) $
lookup envvar env
addHost = maybeAddParam "host" "PGHOST"
addPort = maybeAddParam "port" "PGPORT"
addUser = maybeAddParam "user" "PGUSER"
addPass = maybeAddParam "password" "PGPASS"
addDatabase = maybeAddParam "dbname" "PGDATABASE"
refName :: DBName -> DBName -> DBName
refName (DBName table) (DBName column) =
DBName $ T.concat [table, "_", column, "_fkey"]
udToPair :: UniqueDef -> (DBName, [DBName])
udToPair ud = (uniqueDBName ud, map snd $ uniqueFields ud)