squeal-postgresql-0.9.0.0: Squeal PostgreSQL Library
Copyright(c) Eitan Chatav 2019
Maintainereitan@morphism.tech
Stabilityexperimental
Safe HaskellNone
LanguageHaskell2010

Squeal.PostgreSQL.Expression.Parameter

Description

out-of-line parameters

Synopsis

Parameter

class KnownNat ix => HasParameter (ix :: Nat) (params :: [NullType]) (ty :: NullType) | ix 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

Instances details
(KnownNat ix, HasParameter' ix params ix params x) => HasParameter ix params x Source # 
Instance details

Defined in Squeal.PostgreSQL.Expression.Parameter

Methods

parameter :: forall (db :: SchemasType) (grp :: Grouping) (lat :: FromType) (with :: FromType) (from :: FromType). TypeExpression db x -> Expression grp lat with db params from x Source #

(TypeError ('Text "Tried to get the param at index 0, but params are 1-indexed") :: Constraint, x ~ (Any :: NullType)) => HasParameter 0 params x Source # 
Instance details

Defined in Squeal.PostgreSQL.Expression.Parameter

Methods

parameter :: forall (db :: SchemasType) (grp :: Grouping) (lat :: FromType) (with :: FromType) (from :: FromType). TypeExpression db x -> Expression grp lat with db params from x Source #

param Source #

Arguments

:: forall n ty lat with db params from grp. (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)

Parameter Internals

class KnownNat ix => HasParameter' (originalIx :: Nat) (allParams :: [NullType]) (ix :: Nat) (params :: [NullType]) (ty :: NullType) | ix params -> ty Source #

HasParameter' is an implementation detail of HasParameter allowing us to include the full parameter list in our errors.

Instances

Instances details
(KnownNat ix, HasParameter' originalIx allParams (ix - 1) xs x, params ~ (y ': xs), ParamOutOfBoundsError originalIx allParams params) => HasParameter' originalIx allParams ix params x Source # 
Instance details

Defined in Squeal.PostgreSQL.Expression.Parameter

(params ~ (y ': xs), y ~ x, ParamOutOfBoundsError originalIx allParams params, ParamTypeMismatchError originalIx allParams x y) => HasParameter' originalIx allParams 1 params x Source # 
Instance details

Defined in Squeal.PostgreSQL.Expression.Parameter

type family ParamOutOfBoundsError (originalIx :: Nat) (allParams :: [NullType]) (params :: [NullType]) :: Constraint where ... Source #

ParamOutOfBoundsError reports a nicer error with more context when we try to do an out-of-bounds lookup successfully do a lookup but find a different field than we expected, or when we find ourself out of bounds

Equations

ParamOutOfBoundsError originalIx allParams '[] = TypeError ((('Text "Index " :<>: 'ShowType originalIx) :<>: 'Text " is out of bounds in 1-indexed parameter list:") :$$: 'ShowType allParams) 
ParamOutOfBoundsError _ _ _ = () 

type family ParamTypeMismatchError (originalIx :: Nat) (allParams :: [NullType]) (found :: NullType) (expected :: NullType) :: Constraint where ... Source #

ParamTypeMismatchError reports a nicer error with more context when we successfully do a lookup but find a different field than we expected, or when we find ourself out of bounds

Equations

ParamTypeMismatchError _ _ found found = () 
ParamTypeMismatchError originalIx allParams found expected = TypeError ((((((('Text "Type mismatch when looking up param at index " :<>: 'ShowType originalIx) :$$: 'Text "in 1-indexed parameter list:") :$$: ('Text " " :<>: 'ShowType allParams)) :$$: 'Text "") :$$: ('Text "Expected: " :<>: 'ShowType expected)) :$$: ('Text "But found: " :<>: 'ShowType found)) :$$: 'Text "")