Moduleselda-0.5.2.1Haskell2010

Database.Selda.MakeSelectors

Utilities for creating selectors for non-record types. In general, you should really use record types for your tables and their record labels (i.e. #label) as selectors using the OverloadedLabels extension instead.

1 type
1 class
2 values

Packageselda-0.5.2.1
Exports4
LanguageHaskell2010
LicenceMIT
SourceMakeSelectors.hs

typetype Selectors r = Sels r (Rep r)

An inductive tuple of selectors for the given relation.

classclass GSelectors t (f :: Type -> Type) where

Any table type that can have selectors generated.

Instances4GSelectors

GSelectors t (a :*: (b :*: c)) => GSelectors t ((a :*: b) :*: c)Defined in selda-0.5.2.1 · Database.Selda.MakeSelectors
(GSelectors t a, GSelectors t b, Sels t (a :*: b) ~ (Sels t a :*: Sels t b)) => GSelectors t (a :*: b)Defined in selda-0.5.2.1 · Database.Selda.MakeSelectors
(SqlRow t, SqlType a) => GSelectors t (K1 i a)Defined in selda-0.5.2.1 · Database.Selda.MakeSelectors
(GSelectors t f, Sels t f ~ Sels t (M1 x y f)) => GSelectors t (M1 x y f)Defined in selda-0.5.2.1 · Database.Selda.MakeSelectors

valueselectors :: (Relational a, GSelectors a (Rep a)) => Table a -> Selectors a

Generate selector functions for the given table. Selectors can be used to access the fields of a query result tuple, avoiding the need to pattern match on the entire tuple.

tbl :: Table (Int, Text)
tbl = table "foo" []
(tblBar :*: tblBaz) = selectors tbl

q :: Query s Text
q = do
  row <- select tbl
  return (row ! tblBaz)

valuetableWithSelectors

:: (Relational a, GSelectors a (Rep a))
=> TableName
-> [Attr a]
-> (Table a, Selectors a)

A pair of the table with the given name and columns, and all its selectors. For example:

tbl :: Table (Int, Text)
(tbl, tblBar :*: tblBaz)
  =  tableWithSelectors "foo" []

q :: Query s Text
q = tblBaz `from` select tbl