esqueleto-3.3.3.3: src/Database/Esqueleto/Experimental.hs
{-# LANGUAGE CPP
, DataKinds
, FlexibleContexts
, FlexibleInstances
, FunctionalDependencies
, GADTs
, MultiParamTypeClasses
, TypeOperators
, TypeFamilies
, UndecidableInstances
, OverloadedStrings
, PatternSynonyms
#-}
module Database.Esqueleto.Experimental
( -- * Setup
-- $setup
-- * Introduction
-- $introduction
-- * A New Syntax
-- $new-syntax
-- * Documentation
SqlSetOperation(Union, UnionAll, Except, Intersect)
, pattern SelectQuery
, From(..)
, on
, from
, (:&)(..)
-- * Internals
, ToFrom(..)
, ToFromT
, ToMaybe(..)
, ToMaybeT
, ToAlias(..)
, ToAliasT
, ToAliasReference(..)
, ToAliasReferenceT
)
where
import qualified Control.Monad.Trans.Writer as W
import qualified Control.Monad.Trans.State as S
import Control.Monad.Trans.Class (lift)
#if __GLASGOW_HASKELL__ < 804
import Data.Semigroup
#endif
import Data.Proxy (Proxy(..))
import Database.Esqueleto.Internal.PersistentImport
import Database.Esqueleto.Internal.Internal
( SqlExpr(..)
, InnerJoin(..)
, CrossJoin(..)
, LeftOuterJoin(..)
, RightOuterJoin(..)
, FullOuterJoin(..)
, FromClause(..)
, SqlQuery(..)
, SideData(..)
, Value(..)
, JoinKind(..)
, newIdentFor
, SqlSelect(..)
, Mode(..)
, toRawSql
, Ident(..)
, to3, to4, to5, to6, to7, to8
, from3, from4, from5, from6, from7, from8
, veryUnsafeCoerceSqlExprValue
, parensM
, NeedParens(..)
)
import GHC.TypeLits
-- $setup
--
-- If you're already using "Database.Esqueleto", then you can get
-- started using this module just by changing your imports slightly,
-- as well as enabling the [TypeApplications](https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#extension-TypeApplications) extension.
--
-- @
-- {-\# LANGUAGE TypeApplications \#-}
--
-- ...
--
-- import Database.Esqueleto hiding (on, from)
-- import Database.Esqueleto.Experimental
-- @
----------------------------------------------------------------------
-- $introduction
--
-- This module is fully backwards-compatible extension to the @esqueleto@
-- EDSL that expands subquery functionality and enables
-- [SQL set operations](https://en.wikipedia.org/wiki/Set_operations_(SQL\))
-- to be written directly in Haskell. Specifically, this enables:
--
-- * Subqueries in 'JOIN' statements
-- * 'UNION'
-- * 'UNION' 'ALL'
-- * 'INTERSECT'
-- * 'EXCEPT'
--
-- As a consequence of this, several classes of runtime errors are now
-- caught at compile time. This includes missing 'on' clauses and improper
-- handling of @Maybe@ values in outer joins.
--
-- This module can be used in conjunction with the main "Database.Esqueleto"
-- module, but doing so requires qualified imports to avoid ambiguous
-- definitions of 'on' and 'from', which are defined in both modules.
--
-- Below we will give an overview of how to use this module and the
-- features it enables.
----------------------------------------------------------------------
-- $new-syntax
--
-- This module introduces a new syntax that serves to enable the aforementioned
-- features. This new syntax also changes how joins written in the @esqueleto@
-- EDSL to more closely resemble the underlying SQL.
--
-- For our examples, we'll use a schema similar to the one in the Getting Started
-- section of "Database.Esqueleto":
--
-- @
-- share [mkPersist sqlSettings, mkMigrate "migrateAll"] [persist|
-- Person
-- name String
-- age Int Maybe
-- deriving Eq Show
-- BlogPost
-- title String
-- authorId PersonId
-- deriving Eq Show
-- Follow
-- follower PersonId
-- followed PersonId
-- deriving Eq Show
-- |]
-- @
--
-- === Example 1: Simple select
--
-- Let's select all people who are named \"John\".
--
-- ==== "Database.Esqueleto":
--
-- @
-- select $
-- from $ \\people -> do
-- where_ (people ^. PersonName ==. val \"John\")
-- pure people
-- @
--
-- ==== "Database.Esqueleto.Experimental":
--
-- @
-- select $ do
-- people <- from $ Table \@Person
-- where_ (people ^. PersonName ==. val \"John\")
-- pure people
-- @
--
--
-- === Example 2: Select with join
--
-- Let's select all people and their blog posts who are over
-- the age of 18.
--
-- ==== "Database.Esqueleto":
--
-- @
-- select $
-- from $ \\(people \`LeftOuterJoin\` blogPosts) -> do
-- on (people ^. PersonId ==. blogPosts ?. BlogPostAuthorId)
-- where_ (people ^. PersonAge >. val 18)
-- pure (people, blogPosts)
-- @
--
-- ==== "Database.Esqueleto.Experimental":
--
-- Here we use the ':&' operator to pattern match against the joined tables.
--
-- @
-- select $ do
-- (people :& blogPosts) <-
-- from $ Table \@Person
-- \`LeftOuterJoin\` Table \@BlogPost
-- \`on\` (\\(people :& blogPosts) ->
-- people ^. PersonId ==. blogPosts ?. BlogPostAuthorId)
-- where_ (people ^. PersonAge >. val 18)
-- pure (people, blogPosts)
-- @
--
-- === Example 3: Select with multi-table join
--
-- Let's select all people who follow a person named \"John\", including
-- the name of each follower.
--
-- ==== "Database.Esqueleto":
--
-- @
-- select $
-- from $ \\(
-- people1
-- \`InnerJoin\` followers
-- \`InnerJoin\` people2
-- ) -> do
-- on (people1 ^. PersonId ==. followers ^. FollowFollowed)
-- on (followers ^. FollowFollower ==. people2 ^. PersonId)
-- where_ (people1 ^. PersonName ==. val \"John\")
-- pure (followers, people2)
-- @
--
-- ==== "Database.Esqueleto.Experimental":
--
-- In this version, with each successive 'on' clause, only the tables
-- we have already joined into are in scope, so we must pattern match
-- accordingly. In this case, in the second 'InnerJoin', we do not use
-- the first `Person` reference, so we use @_@ as a placeholder to
-- ignore it. This prevents a possible runtime error where a table
-- is referenced before it appears in the sequence of 'JOIN's.
--
-- @
-- select $ do
-- (people1 :& followers :& people2) <-
-- from $ Table \@Person
-- \`InnerJoin` Table \@Follow
-- \`on\` (\\(people1 :& followers) ->
-- people1 ^. PersonId ==. followers ^. FollowFollowed)
-- \`InnerJoin` Table \@Person
-- \`on\` (\\(_ :& followers :& people2) ->
-- followers ^. FollowFollower ==. people2 ^. PersonId)
-- where_ (people1 ^. PersonName ==. val \"John\")
-- pure (followers, people2)
-- @
--
-- === Example 4: Counting results of a subquery
--
-- Let's count the number of people who have posted at least 10 posts
--
-- ==== "Database.Esqueleto":
--
-- @
-- select $ pure $ subSelectCount $
-- from $ \\(
-- people
-- \`InnerJoin\` blogPosts
-- ) -> do
-- on (people ^. PersonId ==. blogPosts ^. BlogPostAuthorId)
-- groupBy (people ^. PersonId)
-- having ((count $ blogPosts ^. BlogPostId) >. val 10)
-- pure people
-- @
--
-- ==== "Database.Esqueleto.Experimental":
--
-- @
-- select $ do
-- peopleWithPosts <-
-- from $ SelectQuery $ do
-- (people :& blogPosts) <-
-- from $ Table \@Person
-- \`InnerJoin\` Table \@BlogPost
-- \`on\` (\\(p :& bP) ->
-- p ^. PersonId ==. bP ^. BlogPostAuthorId)
-- groupBy (people ^. PersonId)
-- having ((count $ blogPosts ^. BlogPostId) >. val 10)
-- pure people
-- pure $ count (peopleWithPosts ^. PersonId)
-- @
--
-- We now have the ability to refactor this
--
-- === Example 5: Sorting the results of a UNION with limits
--
-- Out of all of the posts created by a person and the people they follow,
-- generate a list of the first 25 posts, sorted alphabetically.
--
-- ==== "Database.Esqueleto":
--
-- Since 'UNION' is not supported, this requires using `Database.Esqueleto.rawSql`. (Not shown)
--
-- ==== "Database.Esqueleto.Experimental":
--
-- Since this module supports all set operations (see `SqlSetOperation`), we can use
-- `Union` to write this query.
--
-- @
-- select $ do
-- (authors, blogPosts) <- from $
-- (SelectQuery $ do
-- (author :& blogPost) <-
-- from $ Table \@Person
-- \`InnerJoin\` Table \@BlogPost
-- \`on\` (\\(a :& bP) ->
-- a ^. PersonId ==. bP ^. BlogPostAuthorId)
-- where_ (author ^. PersonId ==. val currentPersonId)
-- pure (author, blogPost)
-- )
-- \`Union\`
-- (SelectQuery $ do
-- (follow :& blogPost :& author) <-
-- from $ Table \@Follow
-- \`InnerJoin\` Table \@BlogPost
-- \`on\` (\\(f :& bP) ->
-- f ^. FollowFollowed ==. bP ^. BlogPostAuthorId)
-- \`InnerJoin\` Table \@Person
-- \`on\` (\\(_ :& bP :& a) ->
-- bP ^. BlogPostAuthorId ==. a ^. PersonId)
-- where_ (follow ^. FollowFollower ==. val currentPersonId)
-- pure (author, blogPost)
-- )
-- orderBy [ asc (blogPosts ^. BlogPostTitle) ]
-- limit 25
-- pure (authors, blogPosts)
-- @
-- | A left-precedence pair. Pronounced \"and\". Used to represent expressions
-- that have been joined together.
--
-- The precedence behavior can be demonstrated by:
--
-- @
-- a :& b :& c == ((a :& b) :& c)
-- @
--
-- See the examples at the beginning of this module to see how this
-- operator is used in 'JOIN' operations.
data (:&) a b = a :& b
infixl 2 :&
-- | Data type that represents SQL set operations. This includes
-- 'UNION', 'UNION' 'ALL', 'EXCEPT', and 'INTERSECT'. This data
-- type is defined as a binary tree, with @SelectQuery@ on the leaves.
--
-- Each constructor corresponding to the aforementioned set operations
-- can be used as an infix function in a @from@ to help with readability
-- and lead to code that closely resembles the underlying SQL. For example,
--
-- @
-- select $ from $
-- (SelectQuery ...)
-- \`Union\`
-- (SelectQuery ...)
-- @
--
-- is translated into
--
-- @
-- SELECT * FROM (
-- (SELECT * FROM ...)
-- UNION
-- (SELECT * FROM ...)
-- )
-- @
--
-- @SelectQuery@ can be used without any of the set operations to construct
-- a subquery. This can be used in 'JOIN' trees. For example,
--
-- @
-- select $ from $
-- Table \@SomeTable
-- \`InnerJoin\` (SelectQuery ...)
-- \`on\` ...
-- @
--
-- is translated into
--
-- @
-- SELECT *
-- FROM SomeTable
-- INNER JOIN (SELECT * FROM ...)
-- ON ...
-- @
data SqlSetOperation a =
Union (SqlSetOperation a) (SqlSetOperation a)
| UnionAll (SqlSetOperation a) (SqlSetOperation a)
| Except (SqlSetOperation a) (SqlSetOperation a)
| Intersect (SqlSetOperation a) (SqlSetOperation a)
| SelectQueryP NeedParens (SqlQuery a)
pattern SelectQuery :: SqlQuery a -> SqlSetOperation a
pattern SelectQuery q = SelectQueryP Never q
-- | Data type that represents the syntax of a 'JOIN' tree. In practice,
-- only the @Table@ constructor is used directly when writing queries. For example,
--
-- @
-- select $ from $ Table \@People
-- @
data From a where
Table :: PersistEntity ent => From (SqlExpr (Entity ent))
SubQuery :: (SqlSelect a' r, SqlSelect a'' r', ToAlias a, a' ~ ToAliasT a, ToAliasReference a', ToAliasReferenceT a' ~ a'')
=> SqlQuery a
-> From a''
SqlSetOperation :: (SqlSelect a' r, ToAlias a, a' ~ ToAliasT a, ToAliasReference a', ToAliasReferenceT a' ~ a'')
=> SqlSetOperation a
-> From a''
InnerJoinFrom :: From a
-> (From b, (a :& b) -> SqlExpr (Value Bool))
-> From (a :& b)
CrossJoinFrom :: From a
-> From b
-> From (a :& b)
LeftJoinFrom :: ToMaybe b
=> From a
-> (From b, (a :& ToMaybeT b) -> SqlExpr (Value Bool))
-> From (a :& ToMaybeT b)
RightJoinFrom :: ToMaybe a
=> From a
-> (From b, (ToMaybeT a :& b) -> SqlExpr (Value Bool))
-> From (ToMaybeT a :& b)
FullJoinFrom :: (ToMaybe a, ToMaybe b )
=> From a
-> (From b, (ToMaybeT a :& ToMaybeT b) -> SqlExpr (Value Bool))
-> From (ToMaybeT a :& ToMaybeT b)
-- | An @ON@ clause that describes how two tables are related. This should be
-- used as an infix operator after a 'JOIN'. For example,
--
-- @
-- select $
-- from $ Table \@Person
-- \`InnerJoin\` Table \@BlogPost
-- \`on\` (\\(p :& bP) ->
-- p ^. PersonId ==. bP ^. BlogPostAuthorId)
-- @
--
on :: ToFrom a => a -> (b -> SqlExpr (Value Bool)) -> (a, b -> SqlExpr (Value Bool))
on = (,)
infix 9 `on`
type JoinErrorMsg jk = 'Text "Missing on statement for " ':<>: 'Text jk
type family ToFromT a where
ToFromT (From a) = a
ToFromT (SqlSetOperation a) = ToAliasReferenceT (ToAliasT a)
ToFromT (LeftOuterJoin a (b, c -> SqlExpr (Value Bool))) = c
ToFromT (FullOuterJoin a (b, c -> SqlExpr (Value Bool))) = c
ToFromT (RightOuterJoin a (b, c -> SqlExpr (Value Bool))) = c
ToFromT (InnerJoin a (b, c -> SqlExpr (Value Bool))) = c
ToFromT (CrossJoin a b) = (ToFromT a :& ToFromT b)
ToFromT (InnerJoin a b) = TypeError (JoinErrorMsg "InnerJoin")
ToFromT (LeftOuterJoin a b) = TypeError (JoinErrorMsg "LeftOuterJoin")
ToFromT (RightOuterJoin a b) = TypeError (JoinErrorMsg "RightOuterJoin")
ToFromT (FullOuterJoin a b) = TypeError (JoinErrorMsg "FullOuterJoin")
{-- Type class magic to allow the use of the `InnerJoin` family of data constructors in from --}
class ToFrom a where
toFrom :: a -> From (ToFromT a)
instance ToFrom (From a) where
toFrom = id
instance {-# OVERLAPPABLE #-} ToFrom (InnerJoin a b) where
toFrom = undefined
instance {-# OVERLAPPABLE #-} ToFrom (LeftOuterJoin a b) where
toFrom = undefined
instance {-# OVERLAPPABLE #-} ToFrom (RightOuterJoin a b) where
toFrom = undefined
instance {-# OVERLAPPABLE #-} ToFrom (FullOuterJoin a b) where
toFrom = undefined
instance (SqlSelect a' r,SqlSelect a'' r', ToAlias a, a' ~ ToAliasT a, ToAliasReference a', ToAliasReferenceT a' ~ a'') => ToFrom (SqlSetOperation a) where
-- If someone uses just a plain SelectQuery it should behave like a normal subquery
toFrom (SelectQueryP _ q) = SubQuery q
-- Otherwise use the SqlSetOperation
toFrom q = SqlSetOperation q
instance (ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b', ToMaybe b', mb ~ ToMaybeT b')
=> ToFrom (LeftOuterJoin a (b, (a' :& mb) -> SqlExpr (Value Bool))) where
toFrom (LeftOuterJoin lhs (rhs, on')) = LeftJoinFrom (toFrom lhs) (toFrom rhs, on')
instance (ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b', ToMaybe a', ma ~ ToMaybeT a', ToMaybe b', mb ~ ToMaybeT b')
=> ToFrom (FullOuterJoin a (b, (ma :& mb) -> SqlExpr (Value Bool))) where
toFrom (FullOuterJoin lhs (rhs, on')) = FullJoinFrom (toFrom lhs) (toFrom rhs, on')
instance (ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b', ToMaybe a', ma ~ ToMaybeT a')
=> ToFrom (RightOuterJoin a (b, (ma :& b') -> SqlExpr (Value Bool))) where
toFrom (RightOuterJoin lhs (rhs, on')) = RightJoinFrom (toFrom lhs) (toFrom rhs, on')
instance (ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b') => ToFrom (InnerJoin a (b, (a' :& b') -> SqlExpr (Value Bool))) where
toFrom (InnerJoin lhs (rhs, on')) = InnerJoinFrom (toFrom lhs) (toFrom rhs, on')
instance (ToFrom a, ToFrom b) => ToFrom (CrossJoin a b) where
toFrom (CrossJoin lhs rhs) = CrossJoinFrom (toFrom lhs) (toFrom rhs)
type family Nullable a where
Nullable (Maybe a) = a
Nullable a = a
type family ToMaybeT a where
ToMaybeT (SqlExpr (Maybe a)) = SqlExpr (Maybe a)
ToMaybeT (SqlExpr (Entity a)) = SqlExpr (Maybe (Entity a))
ToMaybeT (SqlExpr (Value a)) = SqlExpr (Value (Maybe (Nullable a)))
ToMaybeT (a :& b) = (ToMaybeT a :& ToMaybeT b)
ToMaybeT (a, b) = (ToMaybeT a, ToMaybeT b)
ToMaybeT (a, b, c) = (ToMaybeT a, ToMaybeT b, ToMaybeT c)
ToMaybeT (a, b, c, d) = (ToMaybeT a, ToMaybeT b, ToMaybeT c, ToMaybeT d)
ToMaybeT (a, b, c, d, e) = (ToMaybeT a, ToMaybeT b, ToMaybeT c, ToMaybeT d, ToMaybeT e)
ToMaybeT (a, b, c, d, e, f) = (ToMaybeT a, ToMaybeT b, ToMaybeT c, ToMaybeT d, ToMaybeT e, ToMaybeT f)
ToMaybeT (a, b, c, d, e, f, g) = (ToMaybeT a, ToMaybeT b, ToMaybeT c, ToMaybeT d, ToMaybeT e, ToMaybeT f, ToMaybeT g)
ToMaybeT (a, b, c, d, e, f, g, h) = (ToMaybeT a, ToMaybeT b, ToMaybeT c, ToMaybeT d, ToMaybeT e, ToMaybeT f, ToMaybeT g, ToMaybeT h)
class ToMaybe a where
toMaybe :: a -> ToMaybeT a
instance ToMaybe (SqlExpr (Maybe a)) where
toMaybe = id
instance ToMaybe (SqlExpr (Entity a)) where
toMaybe = EMaybe
instance ToMaybe (SqlExpr (Value a)) where
toMaybe = veryUnsafeCoerceSqlExprValue
instance (ToMaybe a, ToMaybe b) => ToMaybe (a :& b) where
toMaybe (a :& b) = (toMaybe a :& toMaybe b)
instance (ToMaybe a, ToMaybe b) => ToMaybe (a,b) where
toMaybe (a, b) = (toMaybe a, toMaybe b)
instance ( ToMaybe a
, ToMaybe b
, ToMaybe c
) => ToMaybe (a,b,c) where
toMaybe = to3 . toMaybe . from3
instance ( ToMaybe a
, ToMaybe b
, ToMaybe c
, ToMaybe d
) => ToMaybe (a,b,c,d) where
toMaybe = to4 . toMaybe . from4
instance ( ToMaybe a
, ToMaybe b
, ToMaybe c
, ToMaybe d
, ToMaybe e
) => ToMaybe (a,b,c,d,e) where
toMaybe = to5 . toMaybe . from5
instance ( ToMaybe a
, ToMaybe b
, ToMaybe c
, ToMaybe d
, ToMaybe e
, ToMaybe f
) => ToMaybe (a,b,c,d,e,f) where
toMaybe = to6 . toMaybe . from6
instance ( ToMaybe a
, ToMaybe b
, ToMaybe c
, ToMaybe d
, ToMaybe e
, ToMaybe f
, ToMaybe g
) => ToMaybe (a,b,c,d,e,f,g) where
toMaybe = to7 . toMaybe . from7
instance ( ToMaybe a
, ToMaybe b
, ToMaybe c
, ToMaybe d
, ToMaybe e
, ToMaybe f
, ToMaybe g
, ToMaybe h
) => ToMaybe (a,b,c,d,e,f,g,h) where
toMaybe = to8 . toMaybe . from8
-- | 'FROM' clause, used to bring entities into scope.
--
-- Internally, this function uses the `From` datatype and the
-- `ToFrom` typeclass. Unlike the old `Database.Esqueleto.from`,
-- this does not take a function as a parameter, but rather
-- a value that represents a 'JOIN' tree constructed out of
-- instances of `ToFrom`. This implementation eliminates certain
-- types of runtime errors by preventing the construction of
-- invalid SQL (e.g. illegal nested-@from@).
from :: ToFrom a => a -> SqlQuery (ToFromT a)
from parts = do
(a, clause) <- runFrom $ toFrom parts
Q $ W.tell mempty{sdFromClause=[clause]}
pure a
where
runFrom :: From a -> SqlQuery (a, FromClause)
runFrom e@Table = do
let ed = entityDef $ getVal e
ident <- newIdentFor (entityDB ed)
let entity = EEntity ident
pure $ (entity, FromStart ident ed)
where
getVal :: PersistEntity ent => From (SqlExpr (Entity ent)) -> Proxy ent
getVal = const Proxy
runFrom (SubQuery subquery) = do
-- We want to update the IdentState without writing the query to side data
(ret, sideData) <- Q $ W.censor (\_ -> mempty) $ W.listen $ unQ subquery
aliasedValue <- toAlias ret
-- Make a fake query with the aliased results, this allows us to ensure that the query is only run once
let aliasedQuery = Q $ W.WriterT $ pure (aliasedValue, sideData)
-- Add the FromQuery that renders the subquery to our side data
subqueryAlias <- newIdentFor (DBName "q")
-- Pass the aliased results of the subquery to the outer query
-- create aliased references from the outer query results (e.g value from subquery will be `subquery`.`value`),
-- this is probably overkill as the aliases should already be unique but seems to be good practice.
ref <- toAliasReference subqueryAlias aliasedValue
pure (ref , FromQuery subqueryAlias (\info -> toRawSql SELECT info aliasedQuery))
runFrom (SqlSetOperation operation) = do
(aliasedOperation, ret) <- aliasQueries operation
ident <- newIdentFor (DBName "u")
ref <- toAliasReference ident ret
pure (ref, FromQuery ident $ operationToSql aliasedOperation)
where
aliasQueries o =
case o of
SelectQueryP p q -> do
(ret, sideData) <- Q $ W.censor (\_ -> mempty) $ W.listen $ unQ q
prevState <- Q $ lift S.get
aliasedRet <- toAlias ret
Q $ lift $ S.put prevState
let p' =
case p of
Parens -> Parens
Never ->
if (sdLimitClause sideData) /= mempty
|| length (sdOrderByClause sideData) > 0 then
Parens
else
Never
pure (SelectQueryP p' $ Q $ W.WriterT $ pure (aliasedRet, sideData), aliasedRet)
Union o1 o2 -> do
(o1', ret) <- aliasQueries o1
(o2', _ ) <- aliasQueries o2
pure (Union o1' o2', ret)
UnionAll o1 o2 -> do
(o1', ret) <- aliasQueries o1
(o2', _ ) <- aliasQueries o2
pure (UnionAll o1' o2', ret)
Except o1 o2 -> do
(o1', ret) <- aliasQueries o1
(o2', _ ) <- aliasQueries o2
pure (Except o1' o2', ret)
Intersect o1 o2 -> do
(o1', ret) <- aliasQueries o1
(o2', _ ) <- aliasQueries o2
pure (Intersect o1' o2', ret)
operationToSql o info =
case o of
SelectQueryP p q ->
let (builder, values) = toRawSql SELECT info q
in (parensM p builder, values)
Union o1 o2 -> doSetOperation "UNION" info o1 o2
UnionAll o1 o2 -> doSetOperation "UNION ALL" info o1 o2
Except o1 o2 -> doSetOperation "EXCEPT" info o1 o2
Intersect o1 o2 -> doSetOperation "INTERSECT" info o1 o2
doSetOperation operationText info o1 o2 =
let
(q1, v1) = operationToSql o1 info
(q2, v2) = operationToSql o2 info
in (q1 <> " " <> operationText <> " " <> q2, v1 <> v2)
runFrom (InnerJoinFrom leftPart (rightPart, on')) = do
(leftVal, leftFrom) <- runFrom leftPart
(rightVal, rightFrom) <- runFrom rightPart
let ret = leftVal :& rightVal
pure $ (ret, FromJoin leftFrom InnerJoinKind rightFrom (Just (on' ret)))
runFrom (CrossJoinFrom leftPart rightPart) = do
(leftVal, leftFrom) <- runFrom leftPart
(rightVal, rightFrom) <- runFrom rightPart
let ret = leftVal :& rightVal
pure $ (ret, FromJoin leftFrom CrossJoinKind rightFrom Nothing)
runFrom (LeftJoinFrom leftPart (rightPart, on')) = do
(leftVal, leftFrom) <- runFrom leftPart
(rightVal, rightFrom) <- runFrom rightPart
let ret = leftVal :& (toMaybe rightVal)
pure $ (ret, FromJoin leftFrom LeftOuterJoinKind rightFrom (Just (on' ret)))
runFrom (RightJoinFrom leftPart (rightPart, on')) = do
(leftVal, leftFrom) <- runFrom leftPart
(rightVal, rightFrom) <- runFrom rightPart
let ret = (toMaybe leftVal) :& rightVal
pure $ (ret, FromJoin leftFrom RightOuterJoinKind rightFrom (Just (on' ret)))
runFrom (FullJoinFrom leftPart (rightPart, on')) = do
(leftVal, leftFrom) <- runFrom leftPart
(rightVal, rightFrom) <- runFrom rightPart
let ret = (toMaybe leftVal) :& (toMaybe rightVal)
pure $ (ret, FromJoin leftFrom FullOuterJoinKind rightFrom (Just (on' ret)))
type family ToAliasT a where
ToAliasT (SqlExpr (Value a)) = SqlExpr (Value a)
ToAliasT (SqlExpr (Entity a)) = SqlExpr (Entity a)
ToAliasT (SqlExpr (Maybe (Entity a))) = SqlExpr (Maybe (Entity a))
ToAliasT (a, b) = (ToAliasT a, ToAliasT b)
ToAliasT (a, b, c) = (ToAliasT a, ToAliasT b, ToAliasT c)
ToAliasT (a, b, c, d) = (ToAliasT a, ToAliasT b, ToAliasT c, ToAliasT d)
ToAliasT (a, b, c, d, e) = (ToAliasT a, ToAliasT b, ToAliasT c, ToAliasT d, ToAliasT e)
ToAliasT (a, b, c, d, e, f) = (ToAliasT a, ToAliasT b, ToAliasT c, ToAliasT d, ToAliasT e, ToAliasT f)
ToAliasT (a, b, c, d, e, f, g) = (ToAliasT a, ToAliasT b, ToAliasT c, ToAliasT d, ToAliasT e, ToAliasT f, ToAliasT g)
ToAliasT (a, b, c, d, e, f, g, h) = (ToAliasT a, ToAliasT b, ToAliasT c, ToAliasT d, ToAliasT e, ToAliasT f, ToAliasT g, ToAliasT h)
-- Tedious tuple magic
class ToAlias a where
toAlias :: a -> SqlQuery (ToAliasT a)
instance ToAlias (SqlExpr (Value a)) where
toAlias v@(EAliasedValue _ _) = pure v
toAlias v = do
ident <- newIdentFor (DBName "v")
pure $ EAliasedValue ident v
instance ToAlias (SqlExpr (Entity a)) where
toAlias v@(EAliasedEntityReference _ _) = pure v
toAlias v@(EAliasedEntity _ _) = pure v
toAlias (EEntity tableIdent) = do
ident <- newIdentFor (DBName "v")
pure $ EAliasedEntity ident tableIdent
instance ToAlias (SqlExpr (Maybe (Entity a))) where
toAlias (EMaybe e) = EMaybe <$> toAlias e
instance (ToAlias a, ToAlias b) => ToAlias (a,b) where
toAlias (a,b) = (,) <$> toAlias a <*> toAlias b
instance ( ToAlias a
, ToAlias b
, ToAlias c
) => ToAlias (a,b,c) where
toAlias x = to3 <$> (toAlias $ from3 x)
instance ( ToAlias a
, ToAlias b
, ToAlias c
, ToAlias d
) => ToAlias (a,b,c,d) where
toAlias x = to4 <$> (toAlias $ from4 x)
instance ( ToAlias a
, ToAlias b
, ToAlias c
, ToAlias d
, ToAlias e
) => ToAlias (a,b,c,d,e) where
toAlias x = to5 <$> (toAlias $ from5 x)
instance ( ToAlias a
, ToAlias b
, ToAlias c
, ToAlias d
, ToAlias e
, ToAlias f
) => ToAlias (a,b,c,d,e,f) where
toAlias x = to6 <$> (toAlias $ from6 x)
instance ( ToAlias a
, ToAlias b
, ToAlias c
, ToAlias d
, ToAlias e
, ToAlias f
, ToAlias g
) => ToAlias (a,b,c,d,e,f,g) where
toAlias x = to7 <$> (toAlias $ from7 x)
instance ( ToAlias a
, ToAlias b
, ToAlias c
, ToAlias d
, ToAlias e
, ToAlias f
, ToAlias g
, ToAlias h
) => ToAlias (a,b,c,d,e,f,g,h) where
toAlias x = to8 <$> (toAlias $ from8 x)
type family ToAliasReferenceT a where
ToAliasReferenceT (SqlExpr (Value a)) = SqlExpr (Value a)
ToAliasReferenceT (SqlExpr (Entity a)) = SqlExpr (Entity a)
ToAliasReferenceT (SqlExpr (Maybe (Entity a))) = SqlExpr (Maybe (Entity a))
ToAliasReferenceT (a,b) = (ToAliasReferenceT a, ToAliasReferenceT b)
ToAliasReferenceT (a,b,c) = (ToAliasReferenceT a, ToAliasReferenceT b, ToAliasReferenceT c)
ToAliasReferenceT (a, b, c, d) = (ToAliasReferenceT a, ToAliasReferenceT b, ToAliasReferenceT c, ToAliasReferenceT d)
ToAliasReferenceT (a, b, c, d, e) = (ToAliasReferenceT a, ToAliasReferenceT b, ToAliasReferenceT c, ToAliasReferenceT d, ToAliasReferenceT e)
ToAliasReferenceT (a, b, c, d, e, f) = (ToAliasReferenceT a, ToAliasReferenceT b, ToAliasReferenceT c, ToAliasReferenceT d, ToAliasReferenceT e, ToAliasReferenceT f)
ToAliasReferenceT (a, b, c, d, e, f, g) = (ToAliasReferenceT a, ToAliasReferenceT b, ToAliasReferenceT c, ToAliasReferenceT d, ToAliasReferenceT e, ToAliasReferenceT f, ToAliasReferenceT g)
ToAliasReferenceT (a, b, c, d, e, f, g, h) = (ToAliasReferenceT a, ToAliasReferenceT b, ToAliasReferenceT c, ToAliasReferenceT d, ToAliasReferenceT e, ToAliasReferenceT f, ToAliasReferenceT g, ToAliasReferenceT h)
-- more tedious tuple magic
class ToAliasReference a where
toAliasReference :: Ident -> a -> SqlQuery (ToAliasReferenceT a)
instance ToAliasReference (SqlExpr (Value a)) where
toAliasReference aliasSource (EAliasedValue aliasIdent _) = pure $ EValueReference aliasSource (\_ -> aliasIdent)
toAliasReference _ v@(ERaw _ _) = toAlias v
toAliasReference _ v@(ECompositeKey _) = toAlias v
toAliasReference s (EValueReference _ b) = pure $ EValueReference s b
instance ToAliasReference (SqlExpr (Entity a)) where
toAliasReference aliasSource (EAliasedEntity ident _) = pure $ EAliasedEntityReference aliasSource ident
toAliasReference _ e@(EEntity _) = toAlias e
toAliasReference s (EAliasedEntityReference _ b) = pure $ EAliasedEntityReference s b
instance ToAliasReference (SqlExpr (Maybe (Entity a))) where
toAliasReference s (EMaybe e) = EMaybe <$> toAliasReference s e
instance (ToAliasReference a, ToAliasReference b) => ToAliasReference (a, b) where
toAliasReference ident (a,b) = (,) <$> (toAliasReference ident a) <*> (toAliasReference ident b)
instance ( ToAliasReference a
, ToAliasReference b
, ToAliasReference c
) => ToAliasReference (a,b,c) where
toAliasReference ident x = fmap to3 $ toAliasReference ident $ from3 x
instance ( ToAliasReference a
, ToAliasReference b
, ToAliasReference c
, ToAliasReference d
) => ToAliasReference (a,b,c,d) where
toAliasReference ident x = fmap to4 $ toAliasReference ident $ from4 x
instance ( ToAliasReference a
, ToAliasReference b
, ToAliasReference c
, ToAliasReference d
, ToAliasReference e
) => ToAliasReference (a,b,c,d,e) where
toAliasReference ident x = fmap to5 $ toAliasReference ident $ from5 x
instance ( ToAliasReference a
, ToAliasReference b
, ToAliasReference c
, ToAliasReference d
, ToAliasReference e
, ToAliasReference f
) => ToAliasReference (a,b,c,d,e,f) where
toAliasReference ident x = to6 <$> (toAliasReference ident $ from6 x)
instance ( ToAliasReference a
, ToAliasReference b
, ToAliasReference c
, ToAliasReference d
, ToAliasReference e
, ToAliasReference f
, ToAliasReference g
) => ToAliasReference (a,b,c,d,e,f,g) where
toAliasReference ident x = to7 <$> (toAliasReference ident $ from7 x)
instance ( ToAliasReference a
, ToAliasReference b
, ToAliasReference c
, ToAliasReference d
, ToAliasReference e
, ToAliasReference f
, ToAliasReference g
, ToAliasReference h
) => ToAliasReference (a,b,c,d,e,f,g,h) where
toAliasReference ident x = to8 <$> (toAliasReference ident $ from8 x)