Like mentionned in my question, I have an unique constraint on a table in which I want to insert some data. I have to check if the data is already present and insert it if not.
That is what I can't seem to be able to do. Here is my code:
import System.Environment (getArgs)
import Database.HDBC
import Database.HDBC.Sqlite3
import Text.Regex.Posix
import qualified Data.ByteString.Char8 as B
getFrom bstr =
bstr =~ "From:.+@.+\\.(fr|com).?" :: B.ByteString
getTo bstr =
bstr =~ "To:.+@.+\\.(fr|com).?" :: B.ByteString
getSubject bstr =
bstr =~ "Subject:.+" :: B.ByteString
main = do
--[dbPath, rawMail] <- getArgs
bstr <- B.getContents
conn <- connectSqlite3 "bmsg.db"
let
sqNomDest = toSql $ getTo bstr
sqNomExped = toSql $ getFrom bstr
-- begin of the problematic part
-- I make a query to know if the entry if already present
qdbefore <- quickQuery' conn "SELECT d_id FROM dest WHERE maildest LIKE ?" [sqNomDest]
qebefore <- quickQuery' conn "SELECT e_id FROM exped WHERE mailexped LIKE ?" [sqNomExped]
-- then if not I insert it and else I return an arbitrary Int
case qdbefore of --my check is probably wrong since that snippet always go to return 0
[[SqlNull]] -> run conn "INSERT INTO dest(maildest) VALUES(?)" [sqNomDest] --unique on the column constraint so if I ran it alone on something already present it would raise an exeption
_ -> return 0
case qebefore of
[[SqlNull]] -> run conn "INSERT INTO exped(mailexped) VALUES(?)" [sqNomExped] --same here for the constraint
_ -> return 0
commit conn
--end of the problematic part
[[qd]] <- quickQuery' conn "SELECT d_id FROM dest WHERE maildest LIKE ?" [sqNomDest]
[[qe]] <- quickQuery' conn "SELECT e_id FROM exped WHERE mailexped LIKE ?" [sqNomExped]
run conn "INSERT INTO mails(d_id, e_id, sujet, mail) VALUES (?, ?, ?, ?)" [qd, qe, toSql $ getSubject bstr, toSql bstr]
commit conn
disconnect conn
-- CREATE TABLE dest
-- (
-- d_id INTEGER PRIMARY KEY,
-- maildest VARCHAR(64) NOT NULL UNIQUE
-- );
-- CREATE TABLE exped
-- (
-- e_id INTEGER PRIMARY KEY,
-- mailexped VARCHAR(64) NOT NULL UNIQUE
-- );
-- CREATE TABLE mails
-- (
-- m_id INTEGER PRIMARY KEY,
-- d_id INTEGER NOT NULL,
-- e_id INTEGER NOT NULL,
-- sujet VARCHAR(128),
-- mail TEXT NOT NULL,
-- CONSTRAINT fk_dest FOREIGN KEY (d_id) REFERENCES dest(d_id),
-- CONSTRAINT fk_exped FOREIGN KEY (e_id) REFERENCES exped(e_id)
-- );
There is no error, it compiles, but the patern match fail when I give it an email that is not already present.
