| 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.
>>>printSQL (parameter @1 int4)($1 :: int4)
Instances
| (KnownNat n, HasParameter (n - 1) xs x, params ~ (y ': xs)) => HasParameter n params x Source # | |
Defined in Squeal.PostgreSQL.Expression.Parameter Methods parameter :: TypeExpression db x -> Expression grp lat with db params from x Source # | |
| params ~ (x ': xs) => HasParameter 1 params x Source # | |
Defined in Squeal.PostgreSQL.Expression.Parameter Methods parameter :: TypeExpression db x -> Expression grp lat with db params from x 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.
>>>printSQL (param @1 @('Null 'PGint4))($1 :: int4)