Servant.Util.Combinators.Sorting.Backend

Applying sorting specifications.

Documentation

class SortingBackend backend where

Implementation of filtering backend.

Associated Types

type SortedValue backend a :: *

The part of object which we are filtering on, provided by server backend implementor.

type SortedValueConstraint backend a :: Constraint

What we require from sorted values in order to be sortable.

type SortedValueConstraint backend a = ()

type BackendOrdering backend :: *

A resulting ordering.

Methods

backendFieldSort :: SortedValueConstraint backend a => SortedValue backend a -> SortingApp backend ('TyNamedParam name a)

Implement SortingApp as sorting on the given field.

fieldSort :: forall name a backend. (SortingBackend backend, SortedValueConstraint backend a) => SortedValue backend a -> SortingApp backend ('TyNamedParam name a)

newtype SortingApp backend param

A function defining a way to apply the given SortingItem (which is sorting order on a single parameter).

Constructors

SortingApp (SortingItemTagged param -> BackendOrdering backend)

type SortingSpecApp backend (allParams :: [TyNamedParam *]) = HList (SortingApp backend) allParams

List of SortingApp functions. Describes how to apply SortingSpec params (each of possible SortingItem) to an SQL query.

Instance of this type can be created using fieldSort function. For example:

sortingSpecApp :: SortingSpecApp ["course" ?: Course, "desc" ?: Text]
sortingSpecApp =
    fieldSort "course" courseField .*.
    fieldSort "desc" descField .*.
    HNil

Annotating fieldSort call with parameter name is not mandatory but recommended to prevent possible mistakes in fieldSorts ordering.

class ApplyToSortItem backend params where

Lookup for appropriate SortingApp in SortingSpecApp and apply it to SortingItem.

Methods

applyToSortItem :: SortingSpecApp backend params -> SortingItem -> Maybe (BackendOrdering backend)

Apply spec app to the given SortingItem We return Maybe here (instead of forcing presence at type-level) for convenience.

Instances

ApplyToSortItem backend ('[] :: [TyNamedParam Type])

Defined in Servant.Util.Combinators.Sorting.Backend

Methods

applyToSortItem :: SortingSpecApp backend '[] -> SortingItem -> Maybe (BackendOrdering backend)

(KnownSymbol name, ApplyToSortItem backend params) => ApplyToSortItem backend ('TyNamedParam name p ': params)

Defined in Servant.Util.Combinators.Sorting.Backend

Methods

applyToSortItem :: SortingSpecApp backend ('TyNamedParam name p ': params) -> SortingItem -> Maybe (BackendOrdering backend)

backendApplySorting :: forall provided base allParams backend. (allParams ~ AllSortingParams provided base, ApplyToSortItem backend allParams) => SortingSpec provided base -> SortingSpecApp backend allParams -> [BackendOrdering backend]

Apply a given SortingSpecApp to a SortingSpec producing a pack of ordering values which define lexicographical sorting order.