Copyright	(c) Eitan Chatav 2019
Maintainer	eitan@morphism.tech
Stability	experimental
Safe Haskell	None
Language	Haskell2010

Squeal.PostgreSQL.Expression.Parameter

Description

Parameters, out-of-line data values

Synopsis

class KnownNat n => HasParameter (n :: Nat) (params :: [NullityType]) (ty :: NullityType) | n params -> ty where
- parameter :: TypeExpression schemas ty -> Expression outer commons grp schemas params from ty
param :: forall n outer commons schemas params from grp ty. (PGTyped schemas ty, HasParameter n params ty) => Expression outer commons grp schemas params from ty

Documentation

class KnownNat n => HasParameter (n :: Nat) (params :: [NullityType]) (ty :: NullityType) | n params -> ty where Source #

A HasParameter constraint is used to indicate a value that is supplied externally to a SQL statement. manipulateParams, queryParams and traversePrepared support specifying data values separately from the SQL command string, in which case params are used to refer to the out-of-line data values.

Minimal complete definition

Nothing

Methods

parameter :: TypeExpression schemas ty -> Expression outer commons grp schemas params from ty Source #

parameter takes a Nat using type application and a TypeExpression.

>>> let expr = parameter @1 int4 :: Expression outer '[] grp schemas '[ 'Null 'PGint4] from ('Null 'PGint4)
>>> printSQL expr
($1 :: int4)

Instances

(KnownNat n, HasParameter (n - 1) params ty) => HasParameter n (ty' ': params) ty Source #
Instance details Defined in Squeal.PostgreSQL.Expression.Parameter Methods parameter :: TypeExpression schemas ty -> Expression outer commons grp schemas (ty' ': params) from ty Source #
HasParameter 1 (ty1 ': tys) ty1 Source #
Instance details Defined in Squeal.PostgreSQL.Expression.Parameter Methods parameter :: TypeExpression schemas ty1 -> Expression outer commons grp schemas (ty1 ': tys) from ty1 Source #

param Source #

Arguments

:: (PGTyped schemas ty, HasParameter n params ty)
=> Expression outer commons grp schemas params from ty	param

param takes a Nat using type application and for basic types, infers a TypeExpression.

>>> let expr = param @1 :: Expression outer commons grp schemas '[ 'Null 'PGint4] from ('Null 'PGint4)
>>> printSQL expr
($1 :: int4)