| Copyright | (c) Eitan Chatav 2019 |
|---|---|
| Maintainer | [email protected] |
| Stability | experimental |
| Safe Haskell | None |
| Language | Haskell2010 |
Squeal.PostgreSQL.Expression.Parameter
Contents
Description
out-of-line parameters
Synopsis
- class KnownNat n => HasParameter (n :: Nat) (params :: [NullType]) (ty :: NullType) | n params -> ty where
- parameter :: TypeExpression db ty -> Expression grp lat with db params from ty
- param :: forall n ty lat with db params from grp. (NullTyped db ty, HasParameter n params ty) => Expression grp lat with db params from ty
Parameter
class KnownNat n => HasParameter (n :: Nat) (params :: [NullType]) (ty :: NullType) | 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 db ty -> Expression grp lat with db params from ty Source #
parameter takes a Nat using type application and a TypeExpression.
>>>let expr = parameter @1 int4 :: Expression lat '[] grp db '[ 'Null 'PGint4] from ('Null 'PGint4)>>>printSQL expr($1 :: int4)
Instances
| (KnownNat n, HasParameter (n - 1) params ty) => HasParameter n (ty' ': params) ty Source # | |
Defined in Squeal.PostgreSQL.Expression.Parameter Methods parameter :: TypeExpression db ty -> Expression grp lat with db (ty' ': params) from ty Source # | |
| HasParameter 1 (ty1 ': tys) ty1 Source # | |
Defined in Squeal.PostgreSQL.Expression.Parameter Methods parameter :: TypeExpression db ty1 -> Expression grp lat with db (ty1 ': tys) from ty1 Source # | |
Arguments
| :: (NullTyped db ty, HasParameter n params ty) | |
| => Expression grp lat with db params from ty | param |
param takes a Nat using type application and for basic types,
infers a TypeExpression.
>>>let expr = param @1 :: Expression grp lat with db '[ 'Null 'PGint4] from ('Null 'PGint4)>>>printSQL expr($1 :: int4)