Add command function returning command tag value of a query

src/Database/PostgreSQL.js

@@ -51,3 +51,26 @@ exports.ffiUnsafeQuery = function(client) {
         };
     };
 };
+
+exports.ffiUnsafeCommand = function(client) {
+    return function(sql) {
+        return function(values) {
+            return function(onError, onSuccess) {
+                var q = client.query({
+                        text: sql,
+                        values: values,
+                        rowMode: 'array',
+                    }).catch(function(err) {
+                        onError(err);
+                    }).then(function(result) {
+                        onSuccess(result.rowCount);
+                    });
+
+                return function (cancelError, cancelerError, cancelerSuccess) {
+                    q.cancel();
+                    cancelerSuccess();
+                };
+            };
+        };
+    };
+};

src/Database/PostgreSQL.purs

@@ -8,6 +8,7 @@ module Database.PostgreSQL
 , newPool
 , withConnection
 , withTransaction
+, command
 , execute
 , query
 , scalar
@@ -25,7 +26,7 @@ import Control.Monad.Error.Class (catchError, throwError)
 import Data.Array (head)
 import Data.Either (Either(..))
 import Foreign (Foreign)
-import Data.Maybe (Maybe(..))
+import Data.Maybe (Maybe)
 import Data.Newtype (class Newtype)
 import Data.Traversable (traverse)
 import Database.PostgreSQL.Row (class FromSQLRow, class ToSQLRow, Row0(..), Row1(..), fromSQLRow, toSQLRow)
@@ -160,6 +161,26 @@ foreign import ffiUnsafeQuery
     -> Array Foreign
     -> EffectFnAff (Array (Array Foreign))
 
-fromRight :: ∀ a b. Either a b -> Maybe b
-fromRight (Left _) = Nothing
-fromRight (Right a) = Just a
+-- | Execute a PostgreSQL query and return its command tag value.
+command
+    :: ∀ i
+     . ToSQLRow i
+    => Connection
+    -> Query i Int
+    -> i
+    -> Aff Int
+command conn (Query sql) values =
+    unsafeCommand conn sql (toSQLRow values)
+
+unsafeCommand
+    :: Connection
+    -> String
+    -> Array Foreign
+    -> Aff Int
+unsafeCommand c s = fromEffectFnAff <<< ffiUnsafeCommand c s
+
+foreign import ffiUnsafeCommand
+    :: Connection
+    -> String
+    -> Array Foreign
+    -> EffectFnAff Int

test/Main.purs

@@ -18,11 +18,10 @@ import Data.JSDate as JSDate
 import Data.Maybe (Maybe(..), fromJust)
 import Data.Newtype (unwrap)
 import Data.Tuple (Tuple(..))
-import Database.PostgreSQL (Connection, PoolConfiguration, Query(Query), Row0(Row0), Row1(Row1), Row2(Row2), Row3(Row3), Row9(Row9), execute, newPool, query, scalar, withConnection, withTransaction)
+import Database.PostgreSQL (Connection, PoolConfiguration, Query(Query), Row0(Row0), Row1(Row1), Row2(Row2), Row3(Row3), Row9(Row9), command, execute, newPool, query, scalar, withConnection, withTransaction)
 import Effect (Effect)
 import Effect.Aff (Aff, error, launchAff)
 import Effect.Class (liftEffect)
-import Effect.Console (logShow)
 import Foreign.Object (Object, fromFoldable)
 import Math ((%))
 import Partial.Unsafe (unsafePartial)
@@ -145,6 +144,14 @@ main = void $ launchAff do
           """) Row0
           liftEffect <<< assert $ deleted == [Row2 "pork" true, Row2 "rookworst" true]
 
+        test conn "delete returning command tag value" $ do
+          insertFood
+          deleted <- command conn (Query """
+            DELETE FROM foods
+            WHERE delicious
+          """) Row0
+          liftEffect <<< assert $ deleted == 2
+
         test conn "handling instant value" $ do
           before <- liftEffect $ (unwrap <<< unInstant) <$> now
           insertFood