Handle numeric values using purescript-decimals

README.md

@@ -4,7 +4,7 @@ purescript-postgresql-client is a PostgreSQL client library for PureScript.
 
 ## NOTE: I WILL NO LONGER BE MAINTAINING THIS LIBRARY. DUE TO THE COUNTLESS PROBLEMS AND PITFALLS IN THE NODE.JS POSTGRESQL LIBRARY IT IS NO MORE FUN BUT JUST A MASSIVE PITA. IF ANYBODY WANTS TO VOLUNTEER, PLEASE LET ME KNOW, AND I WILL TRANSFER OWNERSHIP OF THE REPO. I THINK THE ONLY TWO REAL SOLUTIONS WOULD BE TO EITHER WRITE A NEW LIBPQ BINDING FOR NODE OR TO WRITE A PSC BACKEND FOR A DECENT PLATFORM (NOT NODE.JS).
 
-To use this library, you need to add `pg` as an npm dependency. You can also
+To use this library, you need to add `pg` and `decimal.js` as an npm dependency. You can also
 find this npm library on [https://github.com/brianc/node-postgres][pg].
 
 The purspgpp preprocessor has been replaced by [sqltopurs], which is a code

bower.json

@@ -16,7 +16,8 @@
     "purescript-datetime": "^3.0.0",
     "purescript-bifunctors": "^3.0.0",
     "purescript-eff": "^3.1.0",
-    "purescript-exceptions": "^3.0.0"
+    "purescript-exceptions": "^3.0.0",
+    "purescript-decimals": "^3.4.0"
   },
   "repository": {
     "type": "git",

package.json

@@ -1,6 +1,7 @@
 {
   "name": "purescript-postgresql-client",
   "dependencies": {
+    "decimal.js": "^10.0.0",
     "pg": "^6.1.2"
   }
 }

src/Database/PostgreSQL/Value.purs

@@ -1,5 +1,7 @@
 module Database.PostgreSQL.Value where
 
+import Prelude
+
 import Control.Monad.Eff (kind Effect)
 import Control.Monad.Error.Class (throwError)
 import Control.Monad.Except (runExcept)
@@ -7,13 +9,14 @@ import Data.Array as Array
 import Data.Bifunctor (lmap)
 import Data.ByteString (ByteString)
 import Data.DateTime.Instant (Instant)
-import Data.Either (Either)
+import Data.Decimal (Decimal)
+import Data.Decimal as Decimal
+import Data.Either (Either, note)
 import Data.Foreign (Foreign, isNull, readArray, readBoolean, readChar, readInt, readNumber, readString, toForeign, unsafeFromForeign)
 import Data.List (List)
 import Data.List as List
 import Data.Maybe (Maybe(..))
 import Data.Traversable (traverse)
-import Prelude
 
 -- | Convert things to SQL values.
 class ToSQLValue a where
@@ -90,6 +93,14 @@ instance toSQLValueForeign :: ToSQLValue Foreign where
 instance fromSQLValueForeign :: FromSQLValue Foreign where
     fromSQLValue = pure
 
+instance toSQLValueDecimal :: ToSQLValue Decimal where
+    toSQLValue = Decimal.toString >>> toForeign
+
+instance fromSQLValueDecimal :: FromSQLValue Decimal where
+    fromSQLValue v = do
+        s ← lmap show $ runExcept (readString v)
+        note ("Decimal literal parsing failed: " <> s) (Decimal.fromString s)
+
 foreign import null :: Foreign
 foreign import instantToString :: Instant -> Foreign
 foreign import unsafeIsBuffer :: ∀ a. a -> Boolean

test/Main.purs

@@ -9,8 +9,9 @@ import Control.Monad.Eff (Eff)
 import Control.Monad.Eff.Class (liftEff)
 import Control.Monad.Eff.Exception (EXCEPTION, error)
 import Control.Monad.Error.Class (throwError, try)
+import Data.Decimal as D
 import Data.Maybe (Maybe(..))
-import Database.PostgreSQL (POSTGRESQL, Query(..), PoolConfiguration, execute, newPool, query, Row0(..), Row1(..), Row2(..), Row6(..), scalar, withConnection, withTransaction)
+import Database.PostgreSQL (POSTGRESQL, PoolConfiguration, Query(Query), Row0(Row0), Row1(Row1), Row2(Row2), Row3(Row3), Row9(Row9), execute, newPool, query, scalar, withConnection, withTransaction)
 import Test.Assert (ASSERT, assert)
 
 main :: ∀ eff. Eff (assert :: ASSERT, exception :: EXCEPTION, postgreSQL :: POSTGRESQL | eff) Unit
@@ -21,14 +22,18 @@ main = void $ launchAff do
      CREATE TEMPORARY TABLE foods (
        name text NOT NULL,
        delicious boolean NOT NULL,
+       price NUMERIC(4,2) NOT NULL,
        PRIMARY KEY (name)
      )
     """) Row0
 
     execute conn (Query """
-      INSERT INTO foods (name, delicious)
+      INSERT INTO foods (name, delicious, price)
-      VALUES ($1, $2), ($3, $4), ($5, $6)
+      VALUES ($1, $2, $3), ($4, $5, $6), ($7, $8, $9)
-    """) (Row6 "pork" true "sauerkraut" false "rookworst" true)
+    """) (Row9
+        "pork" true (D.fromString "8.30")
+        "sauerkraut" false (D.fromString "3.30")
+        "rookworst" true (D.fromString "5.60"))
 
     names <- query conn (Query """
       SELECT name
@@ -39,6 +44,14 @@ main = void $ launchAff do
 
     liftEff <<< assert $ names == [Row1 "pork", Row1 "rookworst"]
 
+    sour <- query conn (Query """
+      SELECT name, price
+      FROM foods
+      WHERE NOT delicious
+      ORDER BY name ASC
+    """) Row0
+    liftEff <<< assert $ sour == [Row2 "sauerkraut" (D.fromString "3.30")]
+
     testTransactionCommit conn
     testTransactionRollback conn
 
@@ -48,9 +61,9 @@ main = void $ launchAff do
     deleteAll conn
     withTransaction conn do
       execute conn (Query """
-        INSERT INTO foods (name, delicious)
+        INSERT INTO foods (name, delicious, price)
-        VALUES ($1, $2)
+        VALUES ($1, $2, $3)
-      """) (Row2 "pork" true)
+      """) (Row3 "pork" true (D.fromString "8.30"))
       testCount conn 1
     testCount conn 1
 
@@ -58,9 +71,9 @@ main = void $ launchAff do
     deleteAll conn
     _ <- try $ withTransaction conn do
       execute conn (Query """
-        INSERT INTO foods (name, delicious)
+        INSERT INTO foods (name, delicious, price)
-        VALUES ($1, $2)
+        VALUES ($1, $2, $3)
-      """) (Row2 "pork" true)
+      """) (Row3 "pork" true (D.fromString "8.30"))
       testCount conn 1
       throwError $ error "fail"
     testCount conn 0