Safe Haskell | None |
---|---|
Language | Haskell2010 |
This is an internal module, anything exported by this module may change without a major version bump. Please use only Database.Esqueleto if possible.
Synopsis
- from :: From a => (a -> SqlQuery b) -> SqlQuery b
- newtype Value a = Value {
- unValue :: a
- newtype ValueList a = ValueList a
- data SomeValue where
- class ToSomeValues a where
- toSomeValues :: a -> [SomeValue]
- data InnerJoin a b = a `InnerJoin` b
- data CrossJoin a b = a `CrossJoin` b
- data LeftOuterJoin a b = a `LeftOuterJoin` b
- data RightOuterJoin a b = a `RightOuterJoin` b
- data FullOuterJoin a b = a `FullOuterJoin` b
- data OnClauseWithoutMatchingJoinException = OnClauseWithoutMatchingJoinException String
- data OrderBy
- data DistinctOn
- data Update typ
- data Insertion a
- data LockingKind
- class PersistField a => SqlString a
- class ToBaseId ent where
- type BaseEnt ent :: *
- toBaseIdWitness :: Key (BaseEnt ent) -> Key ent
- data JoinKind
- class IsJoinKind join where
- smartJoin :: a -> b -> join a b
- reifyJoinKind :: join a b -> JoinKind
- class BackendCompatible sup sub where
- projectBackend :: sub -> sup
- data PreprocessedFrom a
- class From a
- class FromPreprocess a
- when_ :: expr (Value Bool) -> () -> expr a -> (expr (Value Bool), expr a)
- then_ :: ()
- else_ :: expr a -> expr a
- where_ :: SqlExpr (Value Bool) -> SqlQuery ()
- on :: SqlExpr (Value Bool) -> SqlQuery ()
- groupBy :: ToSomeValues a => a -> SqlQuery ()
- orderBy :: [SqlExpr OrderBy] -> SqlQuery ()
- rand :: SqlExpr OrderBy
- asc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy
- desc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy
- limit :: Int64 -> SqlQuery ()
- offset :: Int64 -> SqlQuery ()
- distinct :: SqlQuery a -> SqlQuery a
- distinctOn :: [SqlExpr DistinctOn] -> SqlQuery a -> SqlQuery a
- don :: SqlExpr (Value a) -> SqlExpr DistinctOn
- distinctOnOrderBy :: [SqlExpr OrderBy] -> SqlQuery a -> SqlQuery a
- having :: SqlExpr (Value Bool) -> SqlQuery ()
- locking :: LockingKind -> SqlQuery ()
- sub_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a)
- (^.) :: forall typ val. (PersistEntity val, PersistField typ) => SqlExpr (Entity val) -> EntityField val typ -> SqlExpr (Value typ)
- (?.) :: (PersistEntity val, PersistField typ) => SqlExpr (Maybe (Entity val)) -> EntityField val typ -> SqlExpr (Value (Maybe typ))
- val :: PersistField typ => typ -> SqlExpr (Value typ)
- isNothing :: PersistField typ => SqlExpr (Value (Maybe typ)) -> SqlExpr (Value Bool)
- just :: SqlExpr (Value typ) -> SqlExpr (Value (Maybe typ))
- nothing :: SqlExpr (Value (Maybe typ))
- joinV :: SqlExpr (Value (Maybe (Maybe typ))) -> SqlExpr (Value (Maybe typ))
- withNonNull :: PersistField typ => SqlExpr (Value (Maybe typ)) -> (SqlExpr (Value typ) -> SqlQuery a) -> SqlQuery a
- countRows :: Num a => SqlExpr (Value a)
- count :: Num a => SqlExpr (Value typ) -> SqlExpr (Value a)
- countDistinct :: Num a => SqlExpr (Value typ) -> SqlExpr (Value a)
- not_ :: SqlExpr (Value Bool) -> SqlExpr (Value Bool)
- (==.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (>=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (>.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (<=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (<.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (!=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (&&.) :: SqlExpr (Value Bool) -> SqlExpr (Value Bool) -> SqlExpr (Value Bool)
- (||.) :: SqlExpr (Value Bool) -> SqlExpr (Value Bool) -> SqlExpr (Value Bool)
- between :: PersistField a => SqlExpr (Value a) -> (SqlExpr (Value a), SqlExpr (Value a)) -> SqlExpr (Value Bool)
- (+.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
- (-.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
- (/.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
- (*.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
- random_ :: (PersistField a, Num a) => SqlExpr (Value a)
- round_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
- ceiling_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
- floor_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
- min_ :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value (Maybe a))
- max_ :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value (Maybe a))
- sum_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b))
- avg_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b))
- castNum :: (Num a, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
- castNumM :: (Num a, Num b) => SqlExpr (Value (Maybe a)) -> SqlExpr (Value (Maybe b))
- coalesce :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value (Maybe a))
- coalesceDefault :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value a) -> SqlExpr (Value a)
- lower_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
- like :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool)
- ilike :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool)
- (%) :: SqlString s => SqlExpr (Value s)
- concat_ :: SqlString s => [SqlExpr (Value s)] -> SqlExpr (Value s)
- (++.) :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value s)
- castString :: (SqlString s, SqlString r) => SqlExpr (Value s) -> SqlExpr (Value r)
- subList_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (ValueList a)
- valList :: PersistField typ => [typ] -> SqlExpr (ValueList typ)
- justList :: SqlExpr (ValueList typ) -> SqlExpr (ValueList (Maybe typ))
- in_ :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool)
- notIn :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool)
- exists :: SqlQuery () -> SqlExpr (Value Bool)
- notExists :: SqlQuery () -> SqlExpr (Value Bool)
- set :: PersistEntity val => SqlExpr (Entity val) -> [SqlExpr (Update val)] -> SqlQuery ()
- (=.) :: (PersistEntity val, PersistField typ) => EntityField val typ -> SqlExpr (Value typ) -> SqlExpr (Update val)
- (+=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
- (-=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
- (*=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
- (/=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
- case_ :: PersistField a => [(SqlExpr (Value Bool), SqlExpr (Value a))] -> SqlExpr (Value a) -> SqlExpr (Value a)
- toBaseId :: ToBaseId ent => SqlExpr (Value (Key ent)) -> SqlExpr (Value (Key (BaseEnt ent)))
- (<#) :: (a -> b) -> SqlExpr (Value a) -> SqlExpr (Insertion b)
- (<&>) :: SqlExpr (Insertion (a -> b)) -> SqlExpr (Value a) -> SqlExpr (Insertion b)
- subSelect :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value (Maybe a))
- subSelectMaybe :: PersistField a => SqlQuery (SqlExpr (Value (Maybe a))) -> SqlExpr (Value (Maybe a))
- subSelectCount :: (Num a, PersistField a) => SqlQuery ignored -> SqlExpr (Value a)
- subSelectList :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (ValueList a)
- subSelectForeign :: (BackendCompatible SqlBackend (PersistEntityBackend val1), PersistEntity val1, PersistEntity val2, PersistField a) => SqlExpr (Entity val2) -> EntityField val2 (Key val1) -> (SqlExpr (Entity val1) -> SqlExpr (Value a)) -> SqlExpr (Value a)
- subSelectUnsafe :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a)
The pretty face
from :: From a => (a -> SqlQuery b) -> SqlQuery b Source #
FROM
clause: bring entities into scope.
This function internally uses two type classes in order to provide some flexibility of how you may call it. Internally we refer to these type classes as the two different magics.
The innermost magic allows you to use from
with the
following types:
expr (Entity val)
, which brings a single entity into scope.expr (Maybe (Entity val))
, which brings a single entity that may beNULL
into scope. Used forOUTER JOIN
s.- A
JOIN
of any other two types allowed by the innermost magic, where aJOIN
may be anInnerJoin
, aCrossJoin
, aLeftOuterJoin
, aRightOuterJoin
, or aFullOuterJoin
. TheJOINs
have left fixity.
The outermost magic allows you to use from
on any tuples of
types supported by innermost magic (and also tuples of tuples,
and so on), up to 8-tuples.
Note that using from
for the same entity twice does work and
corresponds to a self-join. You don't even need to use two
different calls to from
, you may use a JOIN
or a tuple.
The following are valid examples of uses of from
(the types
of the arguments of the lambda are inside square brackets):
from
$ \person -> ...from
$ \(person, blogPost) -> ...from
$ \(p `LeftOuterJoin
` mb) -> ...from
$ \(p1 `InnerJoin
` f `InnerJoin
` p2) -> ...from
$ \((p1 `InnerJoin
` f) `InnerJoin
` p2) -> ...
The types of the arguments to the lambdas above are, respectively:
person :: ( Esqueleto query expr backend , PersistEntity Person , PersistEntityBackend Person ~ backend ) => expr (Entity Person) (person, blogPost) :: (...) => (expr (Entity Person), expr (Entity BlogPost)) (p `LeftOuterJoin
` mb) :: (...) => InnerJoin (expr (Entity Person)) (expr (Maybe (Entity BlogPost))) (p1 `InnerJoin
` f `InnerJoin
` p2) :: (...) => InnerJoin (InnerJoin (expr (Entity Person)) (expr (Entity Follow))) (expr (Entity Person)) (p1 `InnerJoin
` (f `InnerJoin
` p2)) :: :: (...) => InnerJoin (expr (Entity Person)) (InnerJoin (expr (Entity Follow)) (expr (Entity Person)))
Note that some backends may not support all kinds of JOIN
s.
A single value (as opposed to a whole entity). You may use
(
or ^.
)(
to get a ?.
)Value
from an Entity
.
Instances
Monad Value Source # | |
Functor Value Source # | Since: 1.4.4 |
Applicative Value Source # | |
Eq a => Eq (Value a) Source # | |
Ord a => Ord (Value a) Source # | |
Defined in Database.Esqueleto.Internal.Internal | |
Show a => Show (Value a) Source # | |
ToSomeValues (SqlExpr (Value a)) Source # | |
Defined in Database.Esqueleto.Internal.Internal | |
PersistField a => SqlSelect (SqlExpr (Value a)) (Value a) Source # | You may return any single value (i.e. a single column) from
a |
Defined in Database.Esqueleto.Internal.Internal sqlSelectCols :: IdentInfo -> SqlExpr (Value a) -> (Builder, [PersistValue]) Source # sqlSelectColCount :: Proxy (SqlExpr (Value a)) -> Int Source # sqlSelectProcessRow :: [PersistValue] -> Either Text (Value a) Source # sqlInsertInto :: IdentInfo -> SqlExpr (Value a) -> (Builder, [PersistValue]) Source # |
A list of single values. There's a limited set of functions
able to work with this data type (such as subList_select
,
valList
, in_
and exists
).
Instances
Eq a => Eq (ValueList a) Source # | |
Ord a => Ord (ValueList a) Source # | |
Defined in Database.Esqueleto.Internal.Internal | |
Show a => Show (ValueList a) Source # | |
A wrapper type for for any expr (Value a)
for all a.
class ToSomeValues a where Source #
A class of things that can be converted into a list of SomeValue. It has
instances for tuples and is the reason why groupBy
can take tuples, like
.groupBy
(foo ^.
FooId, foo ^.
FooName, foo ^.
FooType)
toSomeValues :: a -> [SomeValue] Source #
Instances
data InnerJoin a b infixl 2 Source #
Data type that represents an INNER JOIN
(see LeftOuterJoin
for an example).
a `InnerJoin` b infixl 2 |
Instances
IsJoinKind InnerJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal | |
FromPreprocess (InnerJoin a b) => From (InnerJoin a b) Source # | |
data CrossJoin a b infixl 2 Source #
Data type that represents a CROSS JOIN
(see LeftOuterJoin
for an example).
a `CrossJoin` b infixl 2 |
Instances
IsJoinKind CrossJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal | |
FromPreprocess (CrossJoin a b) => From (CrossJoin a b) Source # | |
data LeftOuterJoin a b infixl 2 Source #
Data type that represents a LEFT OUTER JOIN
. For example,
select $from
$ \(person `LeftOuterJoin
` pet) -> ...
is translated into
SELECT ... FROM Person LEFT OUTER JOIN Pet ...
See also: from
.
a `LeftOuterJoin` b infixl 2 |
Instances
IsJoinKind LeftOuterJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal smartJoin :: a -> b -> LeftOuterJoin a b Source # reifyJoinKind :: LeftOuterJoin a b -> JoinKind Source # | |
FromPreprocess (LeftOuterJoin a b) => From (LeftOuterJoin a b) Source # | |
Defined in Database.Esqueleto.Internal.Internal from_ :: SqlQuery (LeftOuterJoin a b) Source # |
data RightOuterJoin a b infixl 2 Source #
Data type that represents a RIGHT OUTER JOIN
(see LeftOuterJoin
for an example).
a `RightOuterJoin` b infixl 2 |
Instances
IsJoinKind RightOuterJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal smartJoin :: a -> b -> RightOuterJoin a b Source # reifyJoinKind :: RightOuterJoin a b -> JoinKind Source # | |
FromPreprocess (RightOuterJoin a b) => From (RightOuterJoin a b) Source # | |
Defined in Database.Esqueleto.Internal.Internal from_ :: SqlQuery (RightOuterJoin a b) Source # |
data FullOuterJoin a b infixl 2 Source #
Data type that represents a FULL OUTER JOIN
(see LeftOuterJoin
for an example).
a `FullOuterJoin` b infixl 2 |
Instances
IsJoinKind FullOuterJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal smartJoin :: a -> b -> FullOuterJoin a b Source # reifyJoinKind :: FullOuterJoin a b -> JoinKind Source # | |
FromPreprocess (FullOuterJoin a b) => From (FullOuterJoin a b) Source # | |
Defined in Database.Esqueleto.Internal.Internal from_ :: SqlQuery (FullOuterJoin a b) Source # |
data OnClauseWithoutMatchingJoinException Source #
Exception thrown whenever on
is used to create an ON
clause but no matching JOIN
is found.
Instances
data DistinctOn Source #
Phantom type used by distinctOn
and don
.
Phantom type for a SET
operation on an entity of the given
type (see set
and '(=.)').
Phantom type used by insertSelect
.
data LockingKind Source #
Different kinds of locking clauses supported by locking
.
Note that each RDBMS has different locking support. The
constructors of this datatype specify only the syntax of the
locking mechanism, not its semantics. For example, even
though both MySQL and PostgreSQL support ForUpdate
, there
are no guarantees that they will behave the same.
Since: 2.2.7
ForUpdate |
Since: 2.2.7 |
ForUpdateSkipLocked |
Since: 2.2.7 |
ForShare |
Since: 2.2.7 |
LockInShareMode |
Since: 2.2.7 |
class PersistField a => SqlString a Source #
Phantom class of data types that are treated as strings by the RDBMS. It has no methods because it's only used to avoid type errors such as trying to concatenate integers.
If you have a custom data type or newtype
, feel free to make
it an instance of this class.
Since: 2.4.0
Instances
SqlString ByteString Source # | Since: 2.3.0 |
Defined in Database.Esqueleto.Internal.Internal | |
SqlString Text Source # | Since: 2.3.0 |
Defined in Database.Esqueleto.Internal.Internal | |
SqlString Text Source # | Since: 2.3.0 |
Defined in Database.Esqueleto.Internal.Internal | |
SqlString Html Source # | Since: 2.3.0 |
Defined in Database.Esqueleto.Internal.Internal | |
a ~ Char => SqlString [a] Source # | Since: 2.3.0 |
Defined in Database.Esqueleto.Internal.Internal | |
SqlString a => SqlString (Maybe a) Source # | Since: 2.4.0 |
Defined in Database.Esqueleto.Internal.Internal |
The guts
(Internal) A kind of JOIN
.
InnerJoinKind | INNER JOIN |
CrossJoinKind | CROSS JOIN |
LeftOuterJoinKind | LEFT OUTER JOIN |
RightOuterJoinKind | RIGHT OUTER JOIN |
FullOuterJoinKind | FULL OUTER JOIN |
class IsJoinKind join where Source #
(Internal) Functions that operate on types (that should be)
of kind JoinKind
.
smartJoin :: a -> b -> join a b Source #
(Internal) smartJoin a b
is a JOIN
of the correct kind.
reifyJoinKind :: join a b -> JoinKind Source #
(Internal) Reify a JoinKind
from a JOIN
. This
function is non-strict.
Instances
IsJoinKind FullOuterJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal smartJoin :: a -> b -> FullOuterJoin a b Source # reifyJoinKind :: FullOuterJoin a b -> JoinKind Source # | |
IsJoinKind RightOuterJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal smartJoin :: a -> b -> RightOuterJoin a b Source # reifyJoinKind :: RightOuterJoin a b -> JoinKind Source # | |
IsJoinKind LeftOuterJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal smartJoin :: a -> b -> LeftOuterJoin a b Source # reifyJoinKind :: LeftOuterJoin a b -> JoinKind Source # | |
IsJoinKind CrossJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal | |
IsJoinKind InnerJoin Source # | |
Defined in Database.Esqueleto.Internal.Internal |
class BackendCompatible sup sub where #
This class witnesses that two backend are compatible, and that you can
convert from the sub
backend into the sup
backend. This is similar
to the HasPersistBackend
and IsPersistBackend
classes, but where you
don't want to fix the type associated with the PersistEntityBackend
of
a record.
Generally speaking, where you might have:
foo :: (PersistEntity
record ,PeristEntityBackend
record ~BaseBackend
backend ,IsSqlBackend
backend )
this can be replaced with:
foo :: (PersistEntity
record, ,PersistEntityBackend
record ~ backend ,BackendCompatible
SqlBackend
backend )
This works for SqlReadBackend
because of the instance
, without needing to go through the BackendCompatible
SqlBackend
SqlReadBackend
BaseBackend
type family.
Likewise, functions that are currently hardcoded to use SqlBackend
can be generalized:
-- before: asdf ::ReaderT
SqlBackend
m () asdf = pure () -- after: asdf' ::BackendCompatible
SqlBackend backend => ReaderT backend m () asdf' = withReaderTprojectBackend
asdf
Since: persistent-2.7.1
projectBackend :: sub -> sup #
data PreprocessedFrom a Source #
Instances
class FromPreprocess a Source #
Instances
(PersistEntity val, BackendCompatible SqlBackend (PersistEntityBackend val)) => FromPreprocess (SqlExpr (Maybe (Entity val))) Source # | |
Defined in Database.Esqueleto.Internal.Internal fromPreprocess :: SqlQuery (SqlExpr (PreprocessedFrom (SqlExpr (Maybe (Entity val))))) Source # | |
(PersistEntity val, BackendCompatible SqlBackend (PersistEntityBackend val)) => FromPreprocess (SqlExpr (Entity val)) Source # | |
Defined in Database.Esqueleto.Internal.Internal fromPreprocess :: SqlQuery (SqlExpr (PreprocessedFrom (SqlExpr (Entity val)))) Source # | |
(FromPreprocess a, FromPreprocess b, IsJoinKind join) => FromPreprocess (join a b) Source # | |
Defined in Database.Esqueleto.Internal.Internal fromPreprocess :: SqlQuery (SqlExpr (PreprocessedFrom (join a b))) Source # |
when_ :: expr (Value Bool) -> () -> expr a -> (expr (Value Bool), expr a) Source #
Syntax sugar for case_
.
Since: 2.1.2
on :: SqlExpr (Value Bool) -> SqlQuery () Source #
An ON
clause, useful to describe how two tables are related. Cross joins
and tuple-joins do not need an on
clause, but InnerJoin
and the various
outer joins do.
If you don't include an on
clause (or include too many!) then a runtime
exception will be thrown.
As an example, consider this simple join:
select
$from
$ \(foo `InnerJoin
` bar) -> doon
(foo^.
FooId==.
bar^.
BarFooId) ...
We need to specify the clause for joining the two columns together. If we had this:
select
$from
$ \(foo `CrossJoin
` bar) -> do ...
Then we can safely omit the on
clause, because the cross join will make
pairs of all records possible.
You can do multiple on
clauses in a query. This query joins three tables,
and has two on
clauses:
select
$from
$ \(foo `InnerJoin
` bar `InnerJoin
` baz) -> doon
(baz^.
BazId==.
bar^.
BarBazId)on
(foo^.
FooId==.
bar^.
BarFooId) ...
Old versions of esqueleto required that you provide the on
clauses in
reverse order. This restriction has been lifted - you can now provide on
clauses in any order, and the SQL should work itself out. The above query is
now totally equivalent to this:
select
$from
$ \(foo `InnerJoin
` bar `InnerJoin
` baz) -> doon
(foo^.
FooId==.
bar^.
BarFooId)on
(baz^.
BazId==.
bar^.
BarBazId) ...
groupBy :: ToSomeValues a => a -> SqlQuery () Source #
GROUP BY
clause. You can enclose multiple columns
in a tuple.
select $from
\(foo `InnerJoin
` bar) -> doon
(foo^.
FooBarId==.
bar^.
BarId)groupBy
(bar^.
BarId, bar^.
BarName) return (bar^.
BarId, bar^.
BarName, countRows)
With groupBy you can sort by aggregate functions, like so
(we used let
to restrict the more general countRows
to
SqlSqlExpr (Value Int)
to avoid ambiguity---the second use of
countRows
has its type restricted by the :: Int
below):
r <- select $from
\(foo `InnerJoin
` bar) -> doon
(foo^.
FooBarId==.
bar^.
BarId)groupBy
$ bar^.
BarName let countRows' =countRows
orderBy
[asc
countRows'] return (bar^.
BarName, countRows') forM_ r $ \(Value
name,Value
count) -> do print name print (count :: Int)
orderBy :: [SqlExpr OrderBy] -> SqlQuery () Source #
ORDER BY
clause. See also asc
and desc
.
Multiple calls to orderBy
get concatenated on the final
query, including distinctOnOrderBy
.
rand :: SqlExpr OrderBy Source #
Deprecated: Since 2.6.0: rand
ordering function is not uniform across all databases! To avoid accidental partiality it will be removed in the next major version.
ORDER BY random()
clause.
Since: 1.3.10
asc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy Source #
Ascending order of this field or SqlExpression.
desc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy Source #
Descending order of this field or SqlExpression.
distinctOn :: [SqlExpr DistinctOn] -> SqlQuery a -> SqlQuery a Source #
DISTINCT ON
. Change the current SELECT
into
SELECT DISTINCT ON (SqlExpressions)
. For example:
select $from
\foo ->distinctOn
[don
(foo ^. FooName),don
(foo ^. FooState)] $ do ...
You can also chain different calls to distinctOn
. The
above is equivalent to:
select $from
\foo ->distinctOn
[don
(foo ^. FooName)] $distinctOn
[don
(foo ^. FooState)] $ do ...
Each call to distinctOn
adds more SqlExpressions. Calls to
distinctOn
override any calls to distinct
.
Note that PostgreSQL requires the SqlExpressions on DISTINCT
ON
to be the first ones to appear on a ORDER BY
. This is
not managed automatically by esqueleto, keeping its spirit
of trying to be close to raw SQL.
Supported by PostgreSQL only.
Since: 2.2.4
don :: SqlExpr (Value a) -> SqlExpr DistinctOn Source #
Erase an SqlExpression's type so that it's suitable to
be used by distinctOn
.
Since: 2.2.4
distinctOnOrderBy :: [SqlExpr OrderBy] -> SqlQuery a -> SqlQuery a Source #
A convenience function that calls both distinctOn
and
orderBy
. In other words,
distinctOnOrderBy
[asc foo, desc bar, desc quux] $ do
...
is the same as:
distinctOn
[don foo, don bar, don quux] $ doorderBy
[asc foo, desc bar, desc quux] ...
Since: 2.2.4
locking :: LockingKind -> SqlQuery () Source #
Add a locking clause to the query. Please read
LockingKind
documentation and your RDBMS manual.
If multiple calls to locking
are made on the same query,
the last one is used.
Since: 2.2.7
sub_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a) Source #
Deprecated: sub_select sub_select is an unsafe function to use. If used with a SqlQuery that returns 0 results, then it may return NULL despite not mentioning Maybe in the return type. If it returns more than 1 result, then it will throw a SQL error. Instead, consider using one of the following alternatives: - subSelect: attaches a LIMIT 1 and the Maybe return type, totally safe. - subSelectMaybe: Attaches a LIMIT 1, useful for a query that already has a Maybe in the return type. - subSelectCount: Performs a count of the query - this is always safe. - subSelectUnsafe: Performs no checks or guarantees. Safe to use with countRows and friends.
Execute a subquery SELECT
in an SqlExpression. Returns a
simple value so should be used only when the SELECT
query
is guaranteed to return just one row.
Deprecated in 3.2.0.
(^.) :: forall typ val. (PersistEntity val, PersistField typ) => SqlExpr (Entity val) -> EntityField val typ -> SqlExpr (Value typ) infixl 9 Source #
Project a field of an entity.
(?.) :: (PersistEntity val, PersistField typ) => SqlExpr (Maybe (Entity val)) -> EntityField val typ -> SqlExpr (Value (Maybe typ)) Source #
Project a field of an entity that may be null.
val :: PersistField typ => typ -> SqlExpr (Value typ) Source #
Lift a constant value from Haskell-land to the query.
isNothing :: PersistField typ => SqlExpr (Value (Maybe typ)) -> SqlExpr (Value Bool) Source #
IS NULL
comparison.
withNonNull :: PersistField typ => SqlExpr (Value (Maybe typ)) -> (SqlExpr (Value typ) -> SqlQuery a) -> SqlQuery a Source #
Project an SqlExpression that may be null, guarding against null cases.
countDistinct :: Num a => SqlExpr (Value typ) -> SqlExpr (Value a) Source #
COUNT(DISTINCT x)
.
Since: 2.4.1
(==.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #
(>=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #
(>.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #
(<=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #
(<.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #
(!=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #
between :: PersistField a => SqlExpr (Value a) -> (SqlExpr (Value a), SqlExpr (Value a)) -> SqlExpr (Value Bool) Source #
BETWEEN
.
@since: 3.1.0
(+.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a) infixl 6 Source #
(-.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a) infixl 6 Source #
(/.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a) infixl 7 Source #
(*.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a) infixl 7 Source #
round_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b) Source #
ceiling_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b) Source #
floor_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b) Source #
sum_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b)) Source #
avg_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b)) Source #
castNum :: (Num a, Num b) => SqlExpr (Value a) -> SqlExpr (Value b) Source #
Allow a number of one type to be used as one of another type via an implicit cast. An explicit cast is not made, this function changes only the types on the Haskell side.
Caveat: Trying to use castNum
from Double
to Int
will not result in an integer, the original fractional
number will still be used! Use round_
, ceiling_
or
floor_
instead.
Safety: This operation is mostly safe due to the Num
constraint between the types and the fact that RDBMSs
usually allow numbers of different types to be used
interchangeably. However, there may still be issues with
the query not being accepted by the RDBMS or persistent
not being able to parse it.
Since: 2.2.9
castNumM :: (Num a, Num b) => SqlExpr (Value (Maybe a)) -> SqlExpr (Value (Maybe b)) Source #
Same as castNum
, but for nullable values.
Since: 2.2.9
coalesce :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value (Maybe a)) Source #
COALESCE
function. Evaluates the arguments in order and
returns the value of the first non-NULL SqlExpression, or NULL
(Nothing) otherwise. Some RDBMSs (such as SQLite) require
at least two arguments; please refer to the appropriate
documentation.
Since: 1.4.3
coalesceDefault :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value a) -> SqlExpr (Value a) Source #
Like coalesce
, but takes a non-nullable SqlExpression
placed at the end of the SqlExpression list, which guarantees
a non-NULL result.
Since: 1.4.3
like :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool) infixr 2 Source #
LIKE
operator.
ilike :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool) infixr 2 Source #
ILIKE
operator (case-insensitive LIKE
).
Supported by PostgreSQL only.
Since: 2.2.3
concat_ :: SqlString s => [SqlExpr (Value s)] -> SqlExpr (Value s) Source #
The CONCAT
function with a variable number of
parameters. Supported by MySQL and PostgreSQL.
(++.) :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value s) infixr 5 Source #
castString :: (SqlString s, SqlString r) => SqlExpr (Value s) -> SqlExpr (Value r) Source #
Cast a string type into Text
. This function
is very useful if you want to use newtype
s, or if you want
to apply functions such as like
to strings of different
types.
Safety: This is a slightly unsafe function, especially if
you have defined your own instances of SqlString
. Also,
since Maybe
is an instance of SqlString
, it's possible
to turn a nullable value into a non-nullable one. Avoid
using this function if possible.
subList_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (ValueList a) Source #
Execute a subquery SELECT
in an SqlExpression. Returns a
list of values.
valList :: PersistField typ => [typ] -> SqlExpr (ValueList typ) Source #
Lift a list of constant value from Haskell-land to the query.
in_ :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool) Source #
IN
operator. For example if you want to select all Person
s by a list
of IDs:
SELECT * FROM Person WHERE Person.id IN (?)
In esqueleto
, we may write the same query above as:
select $from
$ \person -> dowhere_
$ person^.
PersonId `in_
`valList
personIds return person
Where personIds
is of type [Key Person]
.
notIn :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool) Source #
NOT IN
operator.
set :: PersistEntity val => SqlExpr (Entity val) -> [SqlExpr (Update val)] -> SqlQuery () Source #
SET
clause used on UPDATE
s. Note that while it's not
a type error to use this function on a SELECT
, it will
most certainly result in a runtime error.
(=.) :: (PersistEntity val, PersistField typ) => EntityField val typ -> SqlExpr (Value typ) -> SqlExpr (Update val) infixr 3 Source #
(+=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val) infixr 3 Source #
(-=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val) infixr 3 Source #
(*=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val) infixr 3 Source #
(/=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val) infixr 3 Source #
case_ :: PersistField a => [(SqlExpr (Value Bool), SqlExpr (Value a))] -> SqlExpr (Value a) -> SqlExpr (Value a) Source #
CASE
statement. For example:
select $ return $case_
[when_
(exists
$from
$ \p -> dowhere_
(p^.
PersonName==.
val
"Mike"))then_
(sub_select
$from
$ \v -> do let sub =from
$ \c -> dowhere_
(c^.
PersonName==.
val
"Mike") return (c^.
PersonFavNum)where_
(v^.
PersonFavNum >.sub_select
sub) return $count
(v^.
PersonName) +.val
(1 :: Int)) ] (else_
$val
(-1))
This query is a bit complicated, but basically it checks if a person
named "Mike"
exists, and if that person does, run the subquery to find
out how many people have a ranking (by Fav Num) higher than "Mike"
.
NOTE: There are a few things to be aware about this statement.
- This only implements the full CASE statement, it does not implement the "simple" CASE statement.
- At least one
when_
andthen_
is mandatory otherwise it will emit an error. - The
else_
is also mandatory, unlike the SQL statement in which if theELSE
is omitted it will return aNULL
. You can reproduce this vianothing
.
Since: 2.1.2
toBaseId :: ToBaseId ent => SqlExpr (Value (Key ent)) -> SqlExpr (Value (Key (BaseEnt ent))) Source #
Convert an entity's key into another entity's.
This function is to be used when you change an entity's Id
to be
that of another entity. For example:
Bar barNum Int Foo bar BarId fooNum Int Primary bar
For this example, declare:
instance ToBaseId Foo where type BaseEnt Foo = Bar toBaseIdWitness = FooKey
Now you're able to write queries such as:
select
$from
$ (bar `InnerJoin
` foo) -> doon
(toBaseId
(foo^.
FooId)==.
bar^.
BarId) return (bar, foo)
Note: this function may be unsafe to use in conditions not like the one of the example above.
Since: 2.4.3
(<#) :: (a -> b) -> SqlExpr (Value a) -> SqlExpr (Insertion b) Source #
Apply a PersistField
constructor to SqlExpr Value
arguments.
(<&>) :: SqlExpr (Insertion (a -> b)) -> SqlExpr (Value a) -> SqlExpr (Insertion b) Source #
Apply extra SqlExpr Value
arguments to a PersistField
constructor
subSelect :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value (Maybe a)) Source #
Execute a subquery SELECT
in a SqlExpr
. The query passed to this
function will only return a single result - it has a LIMIT 1
passed in to
the query to make it safe, and the return type is Maybe
to indicate that
the subquery might result in 0 rows.
If you find yourself writing
, then consider using
joinV
. subSelect
subSelectMaybe
.
If you're performing a countRows
, then you can use subSelectCount
which
is safe.
If you know that the subquery will always return exactly one row (eg
a foreign key constraint guarantees that you'll get exactly one row), then
consider subSelectUnsafe
, along with a comment explaining why it is safe.
Since: 3.2.0
subSelectMaybe :: PersistField a => SqlQuery (SqlExpr (Value (Maybe a))) -> SqlExpr (Value (Maybe a)) Source #
Execute a subquery SELECT
in a SqlExpr
. This function is a shorthand
for the common
idiom, where you are calling
joinV
. subSelect
subSelect
on an expression that would be Maybe
already.
As an example, you would use this function when calling sum_
or max_
,
which have Maybe
in the result type (for a 0 row query).
Since: 3.2.0
subSelectCount :: (Num a, PersistField a) => SqlQuery ignored -> SqlExpr (Value a) Source #
Performs a COUNT
of the given query in a subSelect
manner. This is
always guaranteed to return a result value, and is completely safe.
Since: 3.2.0
subSelectList :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (ValueList a) Source #
Execute a subquery SELECT
in a SqlExpr
that returns a list. This is an
alias for subList_select
and is provided for symmetry with the other safe
subselect functions.
Since: 3.2.0
:: (BackendCompatible SqlBackend (PersistEntityBackend val1), PersistEntity val1, PersistEntity val2, PersistField a) | |
=> SqlExpr (Entity val2) | An expression representing the table you have access to now. |
-> EntityField val2 (Key val1) | The foreign key field on the table. |
-> (SqlExpr (Entity val1) -> SqlExpr (Value a)) | A function to extract a value from the foreign reference table. |
-> SqlExpr (Value a) |
Performs a sub-select using the given foreign key on the entity. This is useful to extract values that are known to be present by the database schema.
As an example, consider the following persistent definition:
User profile ProfileId Profile name Text
The following query will return the name of the user.
getUserWithName =select
$from
$ user ->pure
(user,subSelectForeign
user UserProfile (^. ProfileName)
Since: 3.2.0
subSelectUnsafe :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a) Source #
Execute a subquery SELECT
in a SqlExpr
. This function is unsafe,
because it can throw runtime exceptions in two cases:
- If the query passed has 0 result rows, then it will return a
NULL
value. Thepersistent
parsing operations will fail on an unexpectedNULL
. - If the query passed returns more than one row, then the SQL engine will fail with an error like "More than one row returned by a subquery used as an expression".
This function is safe if you guarantee that exactly one row will be returned,
or if the result already has a Maybe
type for some reason.
For variants with the safety encoded already, see subSelect
and
subSelectMaybe
. For the most common safe use of this, see subSelectCount
.
Since: 3.2.0