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1. module Database.Esqueleto

   Warning: This module will switch over to the Experimental syntax in an upcoming major version release. Please migrate to the Database.Esqueleto.Legacy module to continue using the old syntax, or translate to the new and improved syntax in Database.Esqueleto.Experimental.

2. data EsqueletoError

   esqueleto	Database.Esqueleto.Internal.Internal

   Exception data type for esqueleto internal errors

3. rawEsqueleto :: forall (m :: Type -> Type) a r backend . (MonadIO m, SqlSelect a r, BackendCompatible SqlBackend backend) => Mode -> SqlQuery a -> ReaderT backend m Int64

   esqueleto	Database.Esqueleto.Internal.Internal

   (Internal) Execute an esqueleto statement inside persistent's SqlPersistT monad.

4. data DeriveEsqueletoRecordSettings

   esqueleto	Database.Esqueleto.Record

   Codegen settings for deriveEsqueletoRecordWith.

5. DeriveEsqueletoRecordSettings :: (String -> String) -> (String -> String) -> (String -> String) -> (String -> String) -> DeriveEsqueletoRecordSettings

   esqueleto	Database.Esqueleto.Record

   No documentation available.

6. defaultDeriveEsqueletoRecordSettings :: DeriveEsqueletoRecordSettings

   esqueleto	Database.Esqueleto.Record

   The default codegen settings for deriveEsqueletoRecord. These defaults will cause you to require {-# LANGUAGE DuplicateRecordFields #-} in certain cases (see deriveEsqueletoRecord.) If you don't want to do this, change the value of sqlFieldModifier so the field names of the generated SQL record different from those of the Haskell record.

7. deriveEsqueletoRecord :: Name -> Q [Dec]

   esqueleto	Database.Esqueleto.Record

   Takes the name of a Haskell record type and creates a variant of that record prefixed with Sql which can be used in esqueleto expressions. This reduces the amount of pattern matching on large tuples required to interact with data extracted with esqueleto. Note that because the input record and the Sql-prefixed record share field names, the {-# LANGUAGE DuplicateRecordFields #-} extension is required in modules that use deriveEsqueletoRecord. Additionally, the {-# LANGUAGE TypeApplications #-} extension is required for some of the generated code. Given the following record:

   data MyRecord = MyRecord
   { myName    :: Text
   , myAge     :: Maybe Int
   , myUser    :: Entity User
   , myAddress :: Maybe (Entity Address)
   }
   

   $(deriveEsqueletoRecord ''MyRecord) will generate roughly the following code:

   data SqlMyRecord =
   SqlMyRecord { myName    :: SqlExpr (Value Text)
   , myAge     :: SqlExpr (Value (Maybe Int))
   , myUser    :: SqlExpr (Entity User)
   , myAddress :: SqlExpr (Maybe (Entity Address))
   }
   
   instance SqlSelect SqlMyRecord MyRecord where
   sqlSelectCols
   identInfo
   SqlMyRecord { myName    = myName
   , myAge     = myAge
   , myUser    = myUser
   , myAddress = myAddress
   } =
   sqlSelectCols identInfo (myName :& myAge :& myUser :& myAddress)
   
   sqlSelectColCount _ =
   sqlSelectColCount
   (Proxy @(   (SqlExpr (Value Text))
   :& (SqlExpr (Value (Maybe Int)))
   :& (SqlExpr (Entity User))
   :& (SqlExpr (Maybe (Entity Address)))))
   
   sqlSelectProcessRow columns =
   first ((fromString "Failed to parse MyRecord: ") <>)
   (evalStateT process columns)
   where
   process = do
   Value myName <- takeColumns @(SqlExpr (Value Text))
   Value myAge  <- takeColumns @(SqlExpr (Value (Maybe Int)))
   myUser       <- takeColumns @(SqlExpr (Entity User))
   myAddress    <- takeColumns @(SqlExpr (Maybe (Entity Address)))
   pure MyRecord { myName = myName
   , myAge = myAge
   , myUser = myUser
   , myAddress = myAddress
   }
   

   Then, we could write a selection function to use the record in queries:

   getMyRecord :: SqlPersistT IO [MyRecord]
   getMyRecord = select myRecordQuery
   
   myRecordQuery :: SqlQuery SqlMyRecord
   myRecordQuery = do
   user :& address <- from $
   table @User
   `leftJoin`
   table @Address
   `on` (do \(user :& address) -> user ^. #address ==. address ?. #id)
   pure
   SqlMyRecord
   { myName = castString $ user ^. #firstName
   , myAge = val 10
   , myUser = user
   , myAddress = address
   }
   

8. deriveEsqueletoRecordWith :: DeriveEsqueletoRecordSettings -> Name -> Q [Dec]

   esqueleto	Database.Esqueleto.Record

   Takes the name of a Haskell record type and creates a variant of that record based on the supplied settings which can be used in esqueleto expressions. This reduces the amount of pattern matching on large tuples required to interact with data extracted with esqueleto. This is a variant of deriveEsqueletoRecord which allows you to avoid the use of {-# LANGUAGE DuplicateRecordFields #-}, by configuring the DeriveEsqueletoRecordSettings used to generate the SQL record.

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