A point geometry sample on MySQL

mysql_gis_sample_point.hs

{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE ConstraintKinds     #-}
{-# LANGUAGE FlexibleInstances   #-}

module Example.Example15 where

import Control.Exception.Safe (SomeException, catch)

-- my library
import DataBase.MySQLX.NodeSession
import DataBase.MySQLX.ResultSet
import DataBase.MySQLX.Statement

import qualified Data.ByteString.Lazy as BL 
import qualified Data.Sequence        as Seq
import           Data.Maybe

import Data.Geometry.Geos.Geometry
import Data.Geometry.Geos.Serialize
import Data.Geometry.Geos.Types

{-
create table points_tbl (`id` int unsigned not null auto_increment, `location` Point not null, primary key(`id`));

insert into points_tbl (location) values (point(1,1));

mysql-sql> select st_astext(location) from points_tbl;
+---------------------+
| st_astext(location) |
+---------------------+
| POINT(1 1)          |
+---------------------+
1 row in set (0.01 sec)

-}

data Geo = Geo { 
   p :: Geometry Point
} deriving Show

geo:: RowFrom Geo 
geo= Geo <$> colVal 

getColGeoPoint :: Row -> Int -> Geometry Point 
getColGeoPoint row idx = getColGeoPoint' $ Seq.index row idx

getColGeoPoint' :: BL.ByteString -> Geometry Point
getColGeoPoint' x = ensurePoint $ fromJust $ readWkb (BL.toStrict $ BL.drop 4 $ getColByteString' x)

getColGeoPoint'' :: BL.ByteString -> Geometry Point
getColGeoPoint'' x = ensurePoint $ fromJust $ readWkb (BL.toStrict $ getColByteString' x)

instance ColumnValuable (Geometry Point) where toColVal' = getColGeoPoint'

example15 :: IO ()
example15 = do
    nodeSess <- openNodeSession $ defaultNodeSesssionInfo {database = "x_protocol_test", user = "root", password="root", port=8000}
    catch ( do
      result <- executeRawSql "select location from points_tbl" nodeSess
      print $ rowFrom geo $ head result
      ) (\(e::SomeException) -> print e)
    closeNodeSession nodeSess

{-
*Example.Example15> example15
Geo {p = PointGeometry (Point (Coordinate2 1.0 1.0)) Nothing}
*Example.Example15>
-}