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dylex / postgresql-typed

Haskell PostgreSQL library with compile-time type inference
http://hackage.haskell.org/package/postgresql-typed
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How to correctly map a DB tuple returned by the query to a Haskell record? #32

Open mistyharsh opened 1 year ago

mistyharsh commented 1 year ago

Haskell newbie trying to understand how I can get this to work. I have a record defined like this:

data EmailConfig = EmailConfig {
  id :: UUID,
  fromName :: ByteString,
  fromEmail :: ByteString,
  apiKey :: ByteString
}

When I execute the SQL query like following, I wish to map it to a record.

selectEmailQ :: PGPreparedQuery (UUID, ByteString, ByteString, ByteString)
selectEmailQ = [pgSQL|$
  SELECT
    id, from_name, from_email, api_key
  FROM
    email_config;
|]

Following the advice from the comments in the StackOverflow, I am making use of uncurry4 function like below to map to a record:

uncurry4 func (a, b, c, d) = func a b c d

getEmailConfig :: PGConnection -> IO [EmailConfig]
getEmailConfig conn = do
  result <- pgQuery conn selectEmailQ
  pure $ map (uncurry4 EmailConfig) result

So, I wonder if this is a correct/idiomatic way of doing the mapping of result to a Haskell record? Or, is there some other better way of achieving this? I looked at the Database.PostgreSQL.Typed.Relation module but I don't think it is meant for this purpose.