readMessageById

This is to just read the message from queue, by given id

src/Database/PGMQ/Simple.hs

@@ -27,6 +27,7 @@ module Database.PGMQ.Simple
   , purgeQueue
   , readMessage
   , readMessageFromArchive
+  , readMessageById
   , readMessages
   , readMessageWithPoll
   , readMessagesWithPoll
@@ -199,6 +200,15 @@ readMessageFromArchive conn queue msgId = do
     [sql| SELECT msg_id, read_ct, enqueued_at, archived_at, vt, message FROM ? WHERE msg_id = ?|]
       (PSQL.QualifiedIdentifier (Just "pgmq") $ T.pack archiveTable, msgId) >>= return . headMay
 
+-- | Read a message from queue with given ID (for querying purposes, doesn't pop message from queue)
+readMessageById :: (SerializableMessage a)
+                => PSQL.Connection -> Queue -> MessageId -> IO (Maybe (Message a))
+readMessageById conn queue msgId = do
+  let queueTable = "q_" <> queue
+  PSQL.query conn
+    [sql| SELECT msg_id, read_ct, enqueued_at, NULL, vt, message FROM ? WHERE msg_id = ?|]
+      (PSQL.QualifiedIdentifier (Just "pgmq") $ T.pack queueTable, msgId) >>= return . headMay
+
 {-| Reads given number of messages from given queue
 
   https://tembo.io/pgmq/api/sql/functions/#read -}