Typson.Pathing

Pathing

Components for constructing JSON paths for queries.

data key :-> path infixr 4

A type operator for building a JSON query path from multiple components.

   type MyQuery = "foo" :-> "bar" :-> 2 :-> "baz"

Instances

(ReflectPath key, ReflectPath path) => ReflectPath (key :-> path :: Type)

Defined in Typson.Pathing

Methods

reflectPath :: proxy (key :-> path) -> NonEmpty PathComponent

type family TypeAtPath (obj :: Type) (tree :: Tree) (path :: k) :: Type where ...

Determine the type of the query result for a path into a JSON schema. Nullability is propagated so that the result will be wrapped with Maybe if one or more components of the path are nullable.

Equations

TypeAtPath obj ('Node aggr ('Edge fieldName q field subTree ': rest)) fieldName = ApQuantity q field

TypeAtPath (f obj) ('IndexedNode k subTree) (key :: k) = ApQuantity 'Nullable obj

TypeAtPath (f obj) ('IndexedNode k subTree) ((key :: k) :-> nextKey) = ApQuantity 'Nullable (TypeAtPath obj subTree nextKey)

TypeAtPath obj ('IndexedNode k subTree) key = TypeError (((((('Text "Invalid JSON path: expected a " :<>: 'ShowType k) :<>: 'Text " index for ") :<>: 'ShowType obj) :<>: 'Text " but got \"") :<>: 'ShowType key) :<>: 'Text "\".")

TypeAtPath obj ('Node aggr ('Edge fieldName q field subFields ': rest)) (fieldName :-> nextKey) = ApQuantity q (TypeAtPath field subFields nextKey)

TypeAtPath obj ('Node aggr ('Edge fieldName q field subFields ': rest)) key = TypeAtPath obj ('Node aggr rest) key

TypeAtPath obj tree (key :: Symbol) = TypeError (MissingKey obj key)

TypeAtPath obj tree ((key :: Symbol) :-> path) = TypeError (MissingKey obj key)

TypeAtPath obj tree (idx :-> nextKey) = TypeError (InvalidKey idx obj)

TypeAtPath obj tree idx = TypeError (InvalidKey idx obj)

typeAtPath

Arguments

:: proxy path

A path proxy

-> repr tree obj

Schema for the type being queried

-> Proxy (TypeAtPath obj tree path)

Get the result type for a query at a given path.

Path Reflection

data PathComponent

Constructors

Key String

Idx Integer

class ReflectPath path where

Methods

reflectPath :: proxy path -> NonEmpty PathComponent

Reflect a type-level path to it's value level PathComponents.

Instances

KnownNat idx => ReflectPath (idx :: Nat)

Defined in Typson.Pathing

Methods

reflectPath :: proxy idx -> NonEmpty PathComponent

KnownSymbol key => ReflectPath (key :: Symbol)

Defined in Typson.Pathing

Methods

reflectPath :: proxy key -> NonEmpty PathComponent

(ReflectPath key, ReflectPath path) => ReflectPath (key :-> path :: Type)

Defined in Typson.Pathing

Methods

reflectPath :: proxy (key :-> path) -> NonEmpty PathComponent

sqlPath :: ReflectPath path => proxy path -> String

Reflect a path as an SQL JSON path string