jimmy/postgrest
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

refactor: move content negotiation logic to Negotiate.hs

Browse Source 
Moves the `negotiateContent` function to `Plan/Negotiate.hs`
module. This also adds comments to describe the current approach
we have for negotiation.

Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>
This commit is contained in:
Taimoor Zaeem
2026-01-02 06:32:17 +08:00
committed by Steve Chavez
parent 76e0e1fbff
commit 9ec5b030ce
3 changed files with 84 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files
postgrest.cabal
+1
View File
@@ -81,6 +81,7 @@ library
PostgREST.Plan
PostgREST.Plan.CallPlan
PostgREST.Plan.MutatePlan
PostgREST.Plan.Negotiate
PostgREST.Plan.ReadPlan
PostgREST.Plan.Types
PostgREST.RangeQuery
src/PostgREST/Plan.hs
+1 -35
View File
@@ -43,6 +43,7 @@ import PostgREST.Error (ApiRequestError (..),
Error (..),
SchemaCacheError (..))
import PostgREST.MediaType (MediaType (..))
import PostgREST.Plan.Negotiate (negotiateContent)
import PostgREST.Query.SqlFragment (sourceCTEName)
import PostgREST.RangeQuery (NonnegRange, allRange,
convertToLimitZeroRange,
@@ -50,7 +51,6 @@ import PostgREST.RangeQuery (NonnegRange, allRange,
import PostgREST.SchemaCache (SchemaCache (..))
import PostgREST.SchemaCache.Identifiers (FieldName,
QualifiedIdentifier (..),
RelIdentifier (..),
Schema)
import PostgREST.SchemaCache.Relationship (Cardinality (..),
Junction (..),
@@ -60,8 +60,6 @@ import PostgREST.SchemaCache.Relationship (Cardinality (..),
import PostgREST.SchemaCache.Representations (DataRepresentation (..),
RepresentationsMap)
import PostgREST.SchemaCache.Routine (MediaHandler (..),
MediaHandlerMap,
ResolvedHandler,
Routine (..),
RoutineMap,
RoutineParam (..),
@@ -1116,35 +1114,3 @@ inferColsEmbedNeeds (Node ReadPlan{select} forest) pkCols
-- they are later concatenated with AND in the QueryBuilder
addFilterToLogicForest :: CoercibleFilter -> [CoercibleLogicTree] -> [CoercibleLogicTree]
addFilterToLogicForest flt lf = CoercibleStmnt flt : lf
-- | Do content negotiation. i.e. choose a media type based on the intersection of accepted/produced media types.
negotiateContent :: AppConfig -> ApiRequest -> QualifiedIdentifier -> [MediaType] -> MediaHandlerMap -> Bool -> Either ApiRequestError ResolvedHandler
negotiateContent conf ApiRequest{iAction=act, iPreferences=Preferences{preferRepresentation=rep}} identifier accepts produces defaultSelect =
case (act, firstAcceptedPick) of
(_, Nothing) -> Left . MediaTypeError $ map MediaType.toMime accepts
(ActDb (ActRelationMut _ _), Just (x, mt)) -> Right (if rep == Just Full then x else NoAgg, mt)
-- no need for an aggregate on HEAD https://github.com/PostgREST/postgrest/issues/2849
-- TODO: despite no aggregate, these are responding with a Content-Type, which is not correct.
(ActDb (ActRelationRead _ True), Just (_, mt)) -> Right (NoAgg, mt)
(ActDb (ActRoutine _ (InvRead True)), Just (_, mt)) -> Right (NoAgg, mt)
(_, Just (x, mt)) -> Right (x, mt)
where
firstAcceptedPick = listToMaybe $ mapMaybe matchMT accepts -- If there are multiple accepted media types, pick the first. This is usual in content negotiation.
matchMT mt = case mt of
-- all the vendored media types have special handling as they have media type parameters, they cannot be overridden
m@(MTVndSingularJSON strip) -> Just (BuiltinAggSingleJson strip, m)
m@MTVndArrayJSONStrip -> Just (BuiltinAggArrayJsonStrip, m)
m@(MTVndPlan (MTVndSingularJSON strip) _ _) -> mtPlanToNothing $ Just (BuiltinAggSingleJson strip, m)
m@(MTVndPlan MTVndArrayJSONStrip _ _) -> mtPlanToNothing $ Just (BuiltinAggArrayJsonStrip, m)
-- TODO the plan should have its own MediaHandler instead of relying on MediaType
m@(MTVndPlan mType _ _) -> mtPlanToNothing $ ((,) . fst <$> lookupHandler mType) <*> pure m
-- all the other media types can be overridden
x -> lookupHandler x
mtPlanToNothing x = if configDbPlanEnabled conf then x else Nothing -- don't find anything if the plan media type is not allowed
lookupHandler mt =
when' defaultSelect (HM.lookup (RelId identifier, MTAny) produces) <|> -- lookup for identifier and `*/*`
when' defaultSelect (HM.lookup (RelId identifier, mt) produces) <|> -- lookup for identifier and a particular media type
HM.lookup (RelAnyElement, mt) produces -- lookup for anyelement and a particular media type
when' :: Bool -> Maybe a -> Maybe a
when' True (Just a) = Just a
when' _ _ = Nothing
src/PostgREST/Plan/Negotiate.hs
+82
View File
@@ -0,0 +1,82 @@
{-|
Module : PostgREST.Plan.Negotiate
Description : PostgREST Content Negotiation
This module contains logic for content negotiation.
RFC: https://datatracker.ietf.org/doc/html/rfc7231#section-3.4
-}
module PostgREST.Plan.Negotiate
( negotiateContent
) where
import qualified Data.HashMap.Strict as HM
import PostgREST.ApiRequest (ApiRequest (..))
import PostgREST.Config (AppConfig (..))
import PostgREST.Error (ApiRequestError (..))
import PostgREST.MediaType (MediaType (..))
import PostgREST.SchemaCache.Identifiers (QualifiedIdentifier (..),
RelIdentifier (..))
import PostgREST.SchemaCache.Routine (MediaHandler (..),
MediaHandlerMap,
ResolvedHandler)
import PostgREST.ApiRequest.Preferences
import PostgREST.ApiRequest.Types
import qualified PostgREST.MediaType as MediaType
import Protolude hiding (from)
-- We have two general cases of return values from database objects
-- (tables/views/functions):
--
-- 1. "un-mime-typed" values, in most of the cases this is a composite/row
-- value, for example for tables or views, but also often for functions.
-- It can be simple integer values or text or bytea as well.
--
-- For this, we need handlers to transform the "non-mime-typed" values
-- into "mimetypes". We have a default builtin handler that does
-- "application/json". We can add more handlers via aggregates.
--
-- 2. "mime-typed" values, which specifically return a domain type that is
-- associated to a certain mimetype. e.g, a function returning only
-- "image/png".
--
-- FIXME:
-- If the function returns a domain type - let's say image/png, we should
-- accept */*, image/*, and image/png.
-- Related issue: https://github.com/PostgREST/postgrest/issues/3391
-- | Do content negotiation. i.e. choose a media type based on the
-- intersection of accepted/produced media types.
negotiateContent :: AppConfig -> ApiRequest -> QualifiedIdentifier -> [MediaType] -> MediaHandlerMap -> Bool -> Either ApiRequestError ResolvedHandler
negotiateContent conf ApiRequest{iAction=act, iPreferences=Preferences{preferRepresentation=rep}} identifier accepts produces defaultSelect =
case (act, firstAcceptedPick) of
(_, Nothing) -> Left . MediaTypeError $ map MediaType.toMime accepts
(ActDb (ActRelationMut _ _), Just (x, mt)) -> Right (if rep == Just Full then x else NoAgg, mt)
-- no need for an aggregate on HEAD https://github.com/PostgREST/postgrest/issues/2849
-- TODO: despite no aggregate, these are responding with a Content-Type, which is not correct.
(ActDb (ActRelationRead _ True), Just (_, mt)) -> Right (NoAgg, mt)
(ActDb (ActRoutine _ (InvRead True)), Just (_, mt)) -> Right (NoAgg, mt)
(_, Just (x, mt)) -> Right (x, mt)
where
firstAcceptedPick = listToMaybe $ mapMaybe matchMT accepts -- If there are multiple accepted media types, pick the first. This is usual in content negotiation.
matchMT mt = case mt of
-- all the vendored media types have special handling as they have media type parameters, they cannot be overridden
m@(MTVndSingularJSON strip) -> Just (BuiltinAggSingleJson strip, m)
m@MTVndArrayJSONStrip -> Just (BuiltinAggArrayJsonStrip, m)
m@(MTVndPlan (MTVndSingularJSON strip) _ _) -> mtPlanToNothing $ Just (BuiltinAggSingleJson strip, m)
m@(MTVndPlan MTVndArrayJSONStrip _ _) -> mtPlanToNothing $ Just (BuiltinAggArrayJsonStrip, m)
-- TODO the plan should have its own MediaHandler instead of relying on MediaType
m@(MTVndPlan mType _ _) -> mtPlanToNothing $ ((,) . fst <$> lookupHandler mType) <*> pure m
-- all the other media types can be overridden
x -> lookupHandler x
mtPlanToNothing x = if configDbPlanEnabled conf then x else Nothing -- don't find anything if the plan media type is not allowed
lookupHandler mt =
when' defaultSelect (HM.lookup (RelId identifier, MTAny) produces) <|> -- lookup for identifier and `*/*`
when' defaultSelect (HM.lookup (RelId identifier, mt) produces) <|> -- lookup for identifier and a particular media type
HM.lookup (RelAnyElement, mt) produces -- lookup for anyelement and a particular media type
when' :: Bool -> Maybe a -> Maybe a
when' True (Just a) = Just a
when' _ _ = Nothing