hasql/library/Hasql/Errors.hs
2024-07-15 03:00:34 +02:00

153 lines
5.6 KiB
Haskell

module Hasql.Errors where
import Data.ByteString.Char8 qualified as BC
import Hasql.Prelude
-- | Error during execution of a session.
data SessionError
= -- | Error during the execution of a query.
-- Comes packed with the query template and a textual representation of the provided params.
QueryError
-- | SQL template.
ByteString
-- | Parameters rendered as human-readable SQL literals.
[Text]
-- | Error details.
CommandError
| -- | Error during the execution of a pipeline.
PipelineError
-- | Error details.
CommandError
deriving (Show, Eq, Typeable)
instance Exception SessionError where
displayException = \case
QueryError query params commandError ->
let queryContext :: Maybe (ByteString, Int)
queryContext = case commandError of
ClientError _ -> Nothing
ResultError resultError -> case resultError of
ServerError _ message _ _ (Just position) -> Just (message, position)
_ -> Nothing
-- find the line number and position of the error
findLineAndPos :: ByteString -> Int -> (Int, Int)
findLineAndPos byteString errorPos =
let (_, line, pos) =
BC.foldl'
( \(total, line, pos) c ->
case total + 1 of
0 -> (total, line, pos)
cursor
| cursor == errorPos -> (-1, line, pos + 1)
| c == '\n' -> (total + 1, line + 1, 0)
| otherwise -> (total + 1, line, pos + 1)
)
(0, 1, 0)
byteString
in (line, pos)
formatErrorContext :: ByteString -> ByteString -> Int -> ByteString
formatErrorContext query message errorPos =
let lines = BC.lines query
(lineNum, linePos) = findLineAndPos query errorPos
in BC.unlines (take lineNum lines)
<> BC.replicate (linePos - 1) ' '
<> "^ "
<> message
prettyQuery :: ByteString
prettyQuery = case queryContext of
Nothing -> query
Just (message, pos) -> formatErrorContext query message pos
in "QueryError!\n"
<> "\n Query:\n"
<> BC.unpack prettyQuery
<> "\n"
<> "\n Params: "
<> show params
<> "\n Error: "
<> renderCommandErrorAsReason commandError
PipelineError commandError ->
"PipelineError!\n Reason: " <> renderCommandErrorAsReason commandError
where
renderCommandErrorAsReason = \case
ClientError (Just message) -> "Client error: " <> show message
ClientError Nothing -> "Client error without details"
ResultError resultError -> case resultError of
ServerError code message details hint position ->
"Server error "
<> BC.unpack code
<> ": "
<> BC.unpack message
<> maybe "" (\d -> "\n Details: " <> BC.unpack d) details
<> maybe "" (\h -> "\n Hint: " <> BC.unpack h) hint
UnexpectedResult message -> "Unexpected result: " <> show message
RowError row column rowError ->
"Error in row " <> show row <> ", column " <> show column <> ": " <> show rowError
UnexpectedAmountOfRows amount ->
"Unexpected amount of rows: " <> show amount
-- |
-- An error of some command in the session.
data CommandError
= -- |
-- An error on the client-side,
-- with a message generated by the \"libpq\" library.
-- Usually indicates problems with connection.
ClientError (Maybe ByteString)
| -- |
-- Some error with a command result.
ResultError ResultError
deriving (Show, Eq)
-- |
-- An error with a command result.
data ResultError
= -- | An error reported by the DB.
ServerError
-- | __Code__. The SQLSTATE code for the error. It's recommended to use
-- <http://hackage.haskell.org/package/postgresql-error-codes
-- the "postgresql-error-codes" package> to work with those.
ByteString
-- | __Message__. The primary human-readable error message(typically one
-- line). Always present.
ByteString
-- | __Details__. An optional secondary error message carrying more
-- detail about the problem. Might run to multiple lines.
(Maybe ByteString)
-- | __Hint__. An optional suggestion on what to do about the problem.
-- This is intended to differ from detail in that it offers advice
-- (potentially inappropriate) rather than hard facts. Might run to
-- multiple lines.
(Maybe ByteString)
-- | __Position__. Error cursor position as an index into the original
-- statement string. Positions are measured in characters not bytes.
(Maybe Int)
| -- |
-- The database returned an unexpected result.
-- Indicates an improper statement or a schema mismatch.
UnexpectedResult Text
| -- |
-- An error of the row reader, preceded by the indexes of the row and column.
RowError Int Int RowError
| -- |
-- An unexpected amount of rows.
UnexpectedAmountOfRows Int
deriving (Show, Eq)
-- |
-- An error during the decoding of a specific row.
data RowError
= -- |
-- Appears on the attempt to parse more columns than there are in the result.
EndOfInput
| -- |
-- Appears on the attempt to parse a @NULL@ as some value.
UnexpectedNull
| -- |
-- Appears when a wrong value parser is used.
-- Comes with the error details.
ValueError Text
deriving (Show, Eq)