Database.PostgreSQL.Query.Functions

Raw query execution

pgQuery :: (HasPostgres m, MonadLogger m, ToSqlBuilder q, FromRow r) => q -> m [r]

Execute query generated by SqlBuilder. Typical use case:

let userName = "Vovka Erohin" :: Text
pgQuery [sqlExp| SELECT id, name FROM users WHERE name = #{userName}|]

Or

let userName = "Vovka Erohin" :: Text
pgQuery $ Qp "SELECT id, name FROM users WHERE name = ?" [userName]

Which is almost the same. In both cases proper value escaping is performed so you stay protected from sql injections.

pgExecute :: (HasPostgres m, MonadLogger m, ToSqlBuilder q) => q -> m Int64

Execute arbitrary query and return count of affected rows

pgQueryEntities :: (ToSqlBuilder q, HasPostgres m, MonadLogger m, Entity a, FromRow a, FromField (EntityId a)) => q -> m [Ent a]

Executes arbitrary query and parses it as entities and their ids

Transactions

pgWithTransaction :: (HasPostgres m, MonadBaseControl IO m, TransactionSafe m) => m a -> m a

Execute all queries inside one transaction. Rollback transaction on exceptions

pgWithSavepoint :: (HasPostgres m, MonadBaseControl IO m, TransactionSafe m) => m a -> m a

Same as pgWithTransaction but executes queries inside savepoint

Work with entities

pgInsertEntity :: forall a m. (HasPostgres m, MonadLogger m, Entity a, ToRow a, FromField (EntityId a)) => a -> m (EntityId a)

Insert new entity and return it's id

pgInsertManyEntities :: forall a m. (Entity a, HasPostgres m, MonadLogger m, ToRow a) => [a] -> m ()

Insert many entities without returning list of id like pgInsertManyEntitiesId does

pgInsertManyEntitiesId :: forall a m. (Entity a, HasPostgres m, MonadLogger m, ToRow a, FromField (EntityId a)) => [a] -> m [EntityId a]

Same as pgInsertEntity but insert many entities at one action. Returns list of id's of inserted entities

pgSelectEntities

Arguments

:: (Functor m, HasPostgres m, MonadLogger m, Entity a, FromRow a, ToSqlBuilder q, FromField (EntityId a))

=> (FN -> FN)

Entity fields name modifier, e.g. ("tablename"<>). Each field of entity will be processed by this modifier before pasting to the query

-> q

part of query just after SELECT .. FROM table.

-> m [Ent a]

Select entities as pairs of (id, entity).

handler :: Handler [Ent a]
handler = do
    now <- liftIO getCurrentTime
    let back = addUTCTime (days  (-7)) now
    pgSelectEntities id
        [sqlExp|WHERE created BETWEEN #{now} AND #{back}
               ORDER BY created|]

handler2 :: Text -> Handler [Ent Foo]
handler2 fvalue = do
    pgSelectEntities ("t"<>)
        [sqlExp|AS t INNER JOIN table2 AS t2
                ON t.t2_id = t2.id
                WHERE t.field = #{fvalue}
                ORDER BY t2.field2|]
   -- Here the query will be: SELECT ... FROM tbl AS t INNER JOIN ...

pgSelectJustEntities :: forall m a q. (Functor m, HasPostgres m, MonadLogger m, Entity a, FromRow a, ToSqlBuilder q) => (FN -> FN) -> q -> m [a]

Same as pgSelectEntities but do not select id

pgSelectEntitiesBy :: forall a m b. (Functor m, HasPostgres m, MonadLogger m, Entity a, ToMarkedRow b, FromRow a, FromField (EntityId a)) => b -> m [Ent a]

Select entities by condition formed from MarkedRow. Usefull function when you know

pgGetEntity :: forall m a. (ToField (EntityId a), Entity a, HasPostgres m, MonadLogger m, FromRow a, Functor m) => EntityId a -> m (Maybe a)

Select entity by id

getUser :: EntityId User ->  Handler User
getUser uid = do
    pgGetEntity uid
        >>= maybe notFound return

pgGetEntityBy

Arguments

:: (Entity a, HasPostgres m, MonadLogger m, ToMarkedRow b, FromField (EntityId a), FromRow a, Functor m)

=> b

uniq constrained list of fields and values

-> m (Maybe (Ent a))

Get entity by some fields constraint

getUser :: UserName -> Handler User
getUser name = do
    pgGetEntityBy
        (MR [("name", mkValue name),
             ("active", mkValue True)])
        >>= maybe notFound return

The query here will be like

pgQuery [sqlExp|SELECT id, name, phone ... FROM users WHERE name = {True}|]

pgDeleteEntity :: forall a m. (Entity a, HasPostgres m, MonadLogger m, ToField (EntityId a), Functor m) => EntityId a -> m ()

Delete entity.

rmUser :: EntityId User -> Handler ()
rmUser uid = do
    pgDeleteEntity uid

pgUpdateEntity :: forall a b m. (ToMarkedRow b, Entity a, HasPostgres m, MonadLogger m, ToField (EntityId a), Functor m, Typeable a, Typeable b) => EntityId a -> b -> m ()

Update entity using ToMarkedRow instanced value. Requires Proxy while EntityId is not a data type.

fixUser :: Text -> EntityId User -> Handler ()
fixUser username uid = do
    pgGetEntity uid
        >>= maybe notFound run
  where
    run user =
        pgUpdateEntity uid
        $ MR [("active", mkValue True)
              ("name", mkValue username)]

pgSelectCount :: forall m a q. (Entity a, HasPostgres m, MonadLogger m, ToSqlBuilder q) => Proxy a -> q -> m Integer

Select count of entities with given query

activeUsers :: Handler Integer
activeUsers = do
    pgSelectCount (Proxy :: Proxy User)
        [sqlExp|WHERE active = #{True}|]

Auxiliary functions

pgRepsertRow

Arguments

:: (HasPostgres m, MonadLogger m, ToMarkedRow wrow, ToMarkedRow urow)

=> Text

Table name

-> wrow

where condition

-> urow

update row

-> m ()

Perform repsert of the same row, first trying "update where" then "insert" with concatenated fields. Which means that if you run

pgRepsertRow "emails" (MR [("user_id", mkValue uid)]) (MR [("email", mkValue email)])

Then firstly will be performed

UPDATE "emails" SET email = '[e-mail]' WHERE "user_id" = 1234

And if no one row is affected (which is returned by pgExecute), then

INSERT INTO "emails" ("user_id", "email") VALUES (1234, '[e-mail]')

will be performed