138 lines
3.9 KiB
Haskell
138 lines
3.9 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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module PgStructure where
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import Data.Functor ( (<$>) )
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import Data.Maybe (mapMaybe)
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import Control.Applicative ( (<*>) )
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import Data.HashMap.Strict hiding (map)
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import qualified Data.ByteString.Lazy as BL
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import qualified Data.Aeson as JSON
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import Database.HDBC hiding (colType, colNullable)
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import Database.HDBC.PostgreSQL
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import Data.Aeson ((.=))
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data Table = Table {
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tableSchema :: String
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, tableName :: String
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, tableInsertable :: Bool
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} deriving (Show)
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instance JSON.ToJSON Table where
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toJSON v = JSON.object [
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"schema" .= tableSchema v
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, "name" .= tableName v
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, "insertable" .= tableInsertable v ]
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toBool :: String -> Bool
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toBool = (== "YES")
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data Column = Column {
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colSchema :: String
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, colTable :: String
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, colName :: String
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, colPosition :: Int
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, colNullable :: Bool
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, colType :: String
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, colUpdatable :: Bool
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, colMaxLen :: Maybe Int
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, colPrecision :: Maybe Int
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} deriving (Show)
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instance JSON.ToJSON Column where
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toJSON c = JSON.object [
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"schema" .= colSchema c
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, "name" .= colName c
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, "position" .= colPosition c
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, "nullable" .= colNullable c
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, "type" .= colType c
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, "updatable" .= colUpdatable c
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, "maxLen" .= colMaxLen c
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, "precision" .= colPrecision c ]
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data TableOptions = TableOptions {
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tblOptcolumns :: HashMap String Column
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, tblOptpkey :: [String]
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}
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instance JSON.ToJSON TableOptions where
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toJSON t = JSON.object [
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"columns" .= tblOptcolumns t
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, "pkey" .= tblOptpkey t ]
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tables :: String -> Connection -> IO [Table]
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tables s conn = do
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r <- quickQuery conn
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"select table_schema, table_name,\
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\ is_insertable_into\
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\ from information_schema.tables\
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\ where table_schema = ?" [toSql s]
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return $ mapMaybe mkTable r
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where
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mkTable [schema, name, insertable] =
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Just $ Table (fromSql schema)
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(fromSql name)
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(toBool (fromSql insertable))
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mkTable _ = Nothing
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columns :: Int -> String -> Connection -> IO [Column]
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columns s t conn = do
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r <- quickQuery conn
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"select table_schema, table_name, column_name, ordinal_position,\
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\ is_nullable, data_type, is_updatable,\
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\ character_maximum_length, numeric_precision\
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\ from information_schema.columns\
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\ where table_schema = ?\
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\ and table_name = ?" [toSql (show s), toSql t]
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return $ mapMaybe mkColumn r
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where
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mkColumn [schema, table, name, pos, nullable, colT, updatable, maxlen, precision] =
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Just $ Column (fromSql schema)
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(fromSql table)
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(fromSql name)
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(fromSql pos)
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(toBool (fromSql nullable))
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(fromSql colT)
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(toBool (fromSql updatable))
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(fromSql maxlen)
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(fromSql precision)
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mkColumn _ = Nothing
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namedColumnHash :: [Column] -> HashMap String Column
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namedColumnHash = fromList . (Prelude.zip =<< Prelude.map colName)
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printTables :: Int -> Connection -> IO BL.ByteString
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printTables schema conn = JSON.encode <$> tables (show schema) conn
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printColumns :: Int -> String -> Connection -> IO BL.ByteString
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printColumns schema table conn =
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JSON.encode <$> (TableOptions <$> cols <*> pkey)
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where
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cols :: IO (HashMap String Column)
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cols = namedColumnHash <$> columns schema table conn
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pkey :: IO [String]
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pkey = primaryKeyColumns schema table conn
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primaryKeyColumns :: Int -> String -> Connection -> IO [String]
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primaryKeyColumns s t conn = do
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r <- quickQuery conn
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"select kc.column_name \
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\ from \
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\ information_schema.table_constraints tc, \
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\ information_schema.key_column_usage kc \
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\where \
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\ tc.constraint_type = 'PRIMARY KEY' \
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\ and kc.table_name = tc.table_name and kc.table_schema = tc.table_schema \
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\ and kc.constraint_name = tc.constraint_name \
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\ and kc.table_schema = ? \
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\ and kc.table_name = ?" [toSql (show s), toSql t]
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return $ map fromSql (concat r)
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