Database.PostgreSQL.Query.TH.Entity

Documentation

data EntityOptions

Options for deriving Entity

Constructors

EntityOptions

Fields

• eoTableName :: String -> String

  Type name to table name converter

• eoColumnNames :: String -> String

  Record field to column name converter

• eoDeriveClasses :: [Name]

  Typeclasses to derive for Id

• eoIdType :: Name

  Base type for Id

Instances

Generic EntityOptions

Associated Types

type Rep EntityOptions :: * -> *

Methods

from :: EntityOptions -> Rep EntityOptions x

to :: Rep EntityOptions x -> EntityOptions

Default EntityOptions

Methods

def :: EntityOptions

type Rep EntityOptions

type Rep EntityOptions = D1 (MetaData "EntityOptions" "Database.PostgreSQL.Query.TH.Entity" "postgresql-query-3.1.0-JIgOGuFIL8OH5talOVcy5c" False) (C1 (MetaCons "EntityOptions" PrefixI True) ((:*:) ((:*:) (S1 (MetaSel (Just Symbol "eoTableName") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (String -> String))) (S1 (MetaSel (Just Symbol "eoColumnNames") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (String -> String)))) ((:*:) (S1 (MetaSel (Just Symbol "eoDeriveClasses") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 [Name])) (S1 (MetaSel (Just Symbol "eoIdType") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Name)))))

deriveEntity :: EntityOptions -> Name -> Q [Dec]

Derives instance for Entity using type name and field names. Also generates type synonim for ID. E.g. code like this:

data Agent = Agent
    { aName          :: !Text
    , aAttributes    :: !HStoreMap
    , aLongWeirdName :: !Int
    } deriving (Ord, Eq, Show)

$(deriveEntity
  def { eoIdType        = ''Id
      , eoTableName     = toUnderscore
      , eoColumnNames   = toUnderscore . drop 1
      , eoDeriveClasses =
        [''Show, ''Read, ''Ord, ''Eq
        , ''FromField, ''ToField, ''PathPiece]
      }
  ''Agent )

Will generate code like this:

instance Database.PostgreSQL.Query.Entity Agent where
    newtype EntityId Agent
        = AgentId {getAgentId :: Id}
        deriving (Show, Read, Ord, Eq, FromField, ToField, PathPiece)
    tableName _ = "agent"
    fieldNames _ = ["name", "attributes", "long_weird_name"]
type AgentId = EntityId Agent

So, you dont need to write it by hands any more.

NOTE: toUnderscore is from package inflections here