Preql.QuasiQuoter.Raw.TH

Documentation

makeQuery :: String -> Q Exp

Convert a rewritten SQL string to a ByteString, leaving width free

sql :: QuasiQuoter

Given a SQL query with ${} antiquotes, splice a pair (Query p r, p) or a function p' -> (Query p r, p) if the SQL string includes both antiquote and positional parameters.

The sql Quasiquoter allows passing parameters to a query by name, inside a ${} antiquote. For example: [sql| SELECT name, age FROM cats WHERE age >= ${minAge} and age < ${maxAge} |] The Haskell term within {} must be a variable in scope; more complex expressions are not supported.

Antiquotes are replaced by positional ($1, $2) parameters supported by Postgres, and the encoded values are sent with PexecParams

Mixed named & numbered parameters are also supported. It is hoped that this will be useful when migrating existing queries. For example: query $ [sql| SELECT name, age FROM cats WHERE age >= ${minAge} and age < $1 |] maxAge Named parameters will be assigned numbers higher than the highest numbered paramater placeholder.

A quote with only named parameters is converted to a tuple '(Query, p)'. For example: ("SELECT name, age FROM cats WHERE age >= $1 and age < $2", (minAge, maxAge)) If there are no parameters, the inner tuple is (), like ("SELECT * FROM cats", ()). If there are both named & numbered params, the splice is a function taking a tuple and returning (Query, p) where p includes both named & numbered params. For example: a -> ("SELECT name, age FROM cats WHERE age >= $1 and age < $2", (a, maxAge))

maxParam :: [Token] -> Word

numberAntiquotes :: Word -> [Token] -> (String, [String])