Merge pull request #608 from ruslantalpa/multilevel_limit

Limit embeded items

CHANGELOG.md

@@ -11,6 +11,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Support column/node renaming `alias:column` - @ruslantalpa
 - Accept posts from HTML forms - @begriffs
 - Ability to order embedded entities - @ruslantalpa
+- Ability to paginate using &limit and &offset parameters - @ruslantalpa
+- Ability to apply limits to embedded entities and enforce --max-rows on all levels - @ruslantalpa, @begriffs 
 
 ### Fixed
 - Return 401 or 403 for access denied rather than 404 - @begriffs

docs/api/reading.md

@@ -172,9 +172,9 @@ GET /people?order=age.nullsfirst
 GET /people?order=age.desc.nullslast
 ```
 
-To filter the embedded items, you need to specify the tree path for the order param like so. 
+To order the embedded items, you need to specify the tree path for the order param like so.
 ```HTTP
-GET /projects?select=id,name,tasks{id,name}&order=id.asc&tasks.order=name.ask
+GET /projects?select=id,name,tasks{id,name}&order=id.asc&tasks.order=name.asc
 ```
 
 
@@ -214,6 +214,15 @@ Range: 0-4
 You can also use open-ended ranges for an offset with no limit:
 `Range: 10-`.
 
+In addition to the `Range` header, you can use `&limit` and `&offset` parameters
+to achieve the same result.
+
+You can also set a limit (but not offset) for the embedded items like so
+```HTTP
+/posts?select=id,title,body,comments{id,email,body}&limit=10&comments.limit=3
+```
+The above request will return the first 10 posts and for each of the posts, 3 comments at most
+
 #### Suppressing Counts
 
 Sometimes knowing the total row count of a query is unnecessary and
@@ -310,6 +319,13 @@ GET /orders?id=eq.1&select=orderId:id, customer:customer_id{customerId:id, custo
 ]
 ```
 
+If you want to apply filters to the embedded items, you can do that like so:
+```HTTP
+GET /clients?id=eq.42&select=id,name,projects{id,name,is_active}&projects.is_active=eq.true
+```
+The above request will return the client with id=42 and all the projects for that client that are still active
+
+
 <div class="admonition note">
     <p class="admonition-title">Design Consideration</p>
     <p>In order for this feature to work as expected after a schema change, PostgREST currently requires to be restarted.</p>

src/PostgREST/ApiRequest.hs

@@ -15,17 +15,18 @@ import           Data.Monoid               ((<>))
 import           Data.Ord                  (comparing)
 import           Data.String.Conversions   (cs)
 import qualified Data.Text                 as T
+import           Text.Read                 (readMaybe)
 import qualified Data.Vector               as V
 import           Network.HTTP.Base         (urlEncodeVars)
 import           Network.HTTP.Types.Header (hAuthorization)
 import           Network.HTTP.Types.URI    (parseSimpleQuery)
 import           Network.Wai               (Request (..))
 import           Network.Wai.Parse         (parseHttpAccept)
-import           PostgREST.RangeQuery      (NonnegRange, rangeRequested)
+import           PostgREST.RangeQuery      (NonnegRange, rangeRequested, restrictRange, rangeGeq, allRange)
 import           PostgREST.Types           (QualifiedIdentifier (..),
                                             Schema, Payload(..),
                                             UniformObjects(..))
-import           Data.Ranged.Ranges        (singletonRange)
+import           Data.Ranged.Ranges        (singletonRange, rangeIntersection)
 
 type RequestBody = BL.ByteString
 
@@ -60,7 +61,7 @@ data ApiRequest = ApiRequest {
   -- | Similar but not identical to HTTP verb, e.g. Create/Invoke both POST
     iAction :: Action
   -- | Requested range of rows within response
-  , iRange  :: NonnegRange
+  , iRange  :: M.HashMap String NonnegRange
   -- | The target, be it calling a proc or accessing a table
   , iTarget :: Target
   -- | The content type the client most desires (or JSON if undecided)
@@ -140,18 +141,19 @@ userApiRequest schema req reqBody =
 
   ApiRequest {
     iAction = action
-  , iRange  = if singular then singletonRange 0 else rangeRequested hdrs
   , iTarget = target
+  , iRange = M.insert "limit" (rangeIntersection headerRange urlRange) $
+      M.fromList [ (cs k, restrictRange (readMaybe =<< v) allRange) | (k,v) <- qParams, isJust v, endingIn ["limit"] k ]
   , iAccepts = pickContentType $ lookupHeader "accept"
   , iPayload = relevantPayload
   , iPreferRepresentation = representation
   , iPreferSingular = singular
   , iPreferCount = not $ singular || hasPrefer "count=none"
-  , iFilters = [ (cs k, fromJust v) | (k,v) <- qParams, isJust v, k /= "select", not (endingIn "order" k) ]
+  , iFilters = [ (cs k, fromJust v) | (k,v) <- qParams, isJust v, k /= "select", k /= "offset", not (endingIn ["order", "limit"] k) ]
   , iSelect = if method == "DELETE"
               then "*"
               else fromMaybe "*" $ fromMaybe (Just "*") $ lookup "select" qParams
-  , iOrder = [(cs k, fromJust v) | (k,v) <- qParams, isJust v, endingIn "order" k ]
+  , iOrder = [(cs k, fromJust v) | (k,v) <- qParams, isJust v, endingIn ["order"] k ]
   , iCanonicalQS = urlEncodeVars
      . sortBy (comparing fst)
      . map (join (***) cs)
@@ -181,10 +183,17 @@ userApiRequest schema req reqBody =
   tokenStr = case T.split (== ' ') (cs auth) of
     ("Bearer" : t : _) -> t
     _                  -> ""
-  endingIn:: T.Text -> T.Text -> Bool
-  endingIn word key = word == lastWord
+  endingIn:: [T.Text] -> T.Text -> Bool
+  endingIn xx key = lastWord `elem` xx
     where lastWord = last $ T.split (=='.') key
 
+  headerRange = if singular then singletonRange 0 else rangeRequested hdrs
+  urlOffsetRange = rangeGeq . fromMaybe (0::Integer) $
+    readMaybe =<< join (lookup "offset" qParams)
+  urlRange = restrictRange
+    (readMaybe =<< join (lookup "limit" qParams))
+    urlOffsetRange
+
 -- PRIVATE ---------------------------------------------------------------
 
 {-|

src/PostgREST/App.hs

@@ -36,6 +36,8 @@ import           Data.Time.Clock.POSIX     (getPOSIXTime)
 import qualified Data.Vector               as V
 import qualified Hasql.Transaction         as H
 
+import qualified Data.HashMap.Strict       as M
+
 import           PostgREST.ApiRequest   (ApiRequest(..), ContentType(..)
                                             , Action(..), Target(..)
                                             , PreferRepresentation (..)
@@ -45,7 +47,7 @@ import           PostgREST.Config          (AppConfig (..))
 import           PostgREST.DbStructure
 import           PostgREST.Error           (errResponse, pgErrResponse)
 import           PostgREST.Parsers
-import           PostgREST.RangeQuery
+import           PostgREST.RangeQuery      (NonnegRange, allRange, rangeOffset, restrictRange)
 import           PostgREST.Middleware
 import           PostgREST.QueryBuilder ( callProc
                                         , addJoinConditions
@@ -101,7 +103,7 @@ app dbStructure conf apiRequest =
         Left e -> return $ responseLBS status400 [jsonH] $ cs e
         Right (q, cq) -> do
           let singular = iPreferSingular apiRequest
-              stm = createReadStatement q cq range singular
+              stm = createReadStatement q cq singular
                     shouldCount (contentType == TextCSV)
           respondToRange $ do
             row <- H.query () stm
@@ -187,7 +189,7 @@ app dbStructure conf apiRequest =
           let p = V.head payload
               jwtSecret = configJwtSecret conf
           respondToRange $ do
-            row <- H.query () (callProc qi p range shouldCount)
+            row <- H.query () (callProc qi p topLevelRange shouldCount)
             returnJWT <- H.query qi doesProcReturnJWT
             let (tableTotal, queryTotal, body) = fromMaybe (Just 0, 0, emptyArray) row
                 (status, contentRange) = rangeHeader queryTotal tableTotal
@@ -219,18 +221,18 @@ app dbStructure conf apiRequest =
   allOrigins = ("Access-Control-Allow-Origin", "*") :: Header
   schema = cs $ configSchema conf
   shouldCount = iPreferCount apiRequest
-  range = restrictRange (configMaxRows conf) $ iRange apiRequest
-  readDbRequest = DbRead <$> buildReadRequest (dbRelations dbStructure) apiRequest
+  topLevelRange = fromMaybe allRange $ M.lookup "limit" $ iRange apiRequest
+  readDbRequest = DbRead <$> buildReadRequest (configMaxRows conf) (dbRelations dbStructure) apiRequest
   mutateDbRequest = DbMutate <$> buildMutateRequest apiRequest
   selectQuery = requestToQuery schema <$> readDbRequest
   countQuery = requestToCountQuery schema <$> readDbRequest
   mutateQuery = requestToQuery schema <$> mutateDbRequest
   readSqlParts = (,) <$> selectQuery <*> countQuery
   mutateSqlParts = (,) <$> selectQuery <*> mutateQuery
-  respondToRange response = if range == emptyRange
+  respondToRange response = if topLevelRange == emptyRange
                             then return $ errResponse status416 "HTTP Range error"
                             else response
-  rangeHeader queryTotal tableTotal = let frm = rangeOffset range
+  rangeHeader queryTotal tableTotal = let frm = rangeOffset topLevelRange
                                           to = frm + toInteger queryTotal - 1
                                           contentRange = contentRangeH frm to (toInteger <$> tableTotal)
                                           status = rangeStatus frm to (toInteger <$> tableTotal)
@@ -287,53 +289,82 @@ augumentRequestWithJoin schema allRels request =
   (first formatRelationError . addRelations schema allRels Nothing) request
   >>= addJoinConditions schema
 
-buildReadRequest :: [Relation] -> ApiRequest -> Either Text ReadRequest
-buildReadRequest allRels apiRequest  =
-  augumentRequestWithJoin schema rels =<<
-  first formatParserError (foldr addFilter <$> (foldr addOrder <$> readRequest <*> ords) <*> flts)
+addFiltersOrdersRanges :: ApiRequest -> Either ParseError (ReadRequest -> ReadRequest)
+addFiltersOrdersRanges apiRequest = foldr1 (liftA2 (.)) [
+    flip (foldr addFilter) <$> filters,
+    flip (foldr addOrder) <$> orders,
+    flip (foldr addRange) <$> ranges
+  ]
+  {-
+  The esence of what is going on above is that we are composing tree functions
+  of type (ReadRequest->ReadRequest) that are in (Either ParseError a) context
+  -}
+  where
+    filters :: Either ParseError [(Path, Filter)]
+    filters = mapM pRequestFilter flts
+      where
+        action = iAction apiRequest
+        flts = if action == ActionRead
+          then iFilters apiRequest
+          else filter (( '.' `elem` ) . fst) $ iFilters apiRequest -- there can be no filters on the root table whre we are doing insert/update
+    orders :: Either ParseError [(Path, [OrderTerm])]
+    orders = mapM pRequestOrder $ iOrder apiRequest
+    ranges :: Either ParseError [(Path, NonnegRange)]
+    ranges = mapM pRequestRange $ M.toList $ iRange apiRequest
+
+treeRestrictRange :: Maybe Integer -> ReadRequest -> Either Text ReadRequest
+treeRestrictRange maxRows_ request = pure $ nodeRestrictRange maxRows_ `fmap` request
+  where
+    nodeRestrictRange :: Maybe Integer -> ReadNode -> ReadNode
+    nodeRestrictRange m (q@Select {range_=r}, i) = (q{range_=restrictRange m r }, i)
+
+buildReadRequest :: Maybe Integer -> [Relation] -> ApiRequest -> Either Text ReadRequest
+buildReadRequest maxRows allRels apiRequest  =
+  treeRestrictRange maxRows =<<
+  augumentRequestWithJoin schema relations =<<
+  first formatParserError readRequest
   where
-    selStr = iSelect apiRequest
-    action = iAction apiRequest
-    target = iTarget apiRequest
     (schema, rootTableName) = fromJust $ -- Make it safe
+      let target = iTarget apiRequest in
       case target of
         (TargetIdent (QualifiedIdentifier s t) ) -> Just (s, t)
         _ -> Nothing
 
-    rootName = if action == ActionRead
-      then rootTableName
-      else sourceCTEName
-    filters = if action == ActionRead
-      then iFilters apiRequest
-      else filter (( '.' `elem` ) . fst) $ iFilters apiRequest -- there can be no filters on the root table whre we are doing insert/update
-    rels = case action of
+    action :: Action
+    action = iAction apiRequest
+
+    readRequest :: Either ParseError ReadRequest
+    readRequest = addFiltersOrdersRanges apiRequest <*>
+      parse (pRequestSelect rootName) ("failed to parse select parameter <<"++selStr++">>") selStr
+      where
+        selStr = iSelect apiRequest
+        rootName = if action == ActionRead
+          then rootTableName
+          else sourceCTEName
+
+    relations :: [Relation]
+    relations = case action of
       ActionCreate -> fakeSourceRelations ++ allRels
       ActionUpdate -> fakeSourceRelations ++ allRels
       _       -> allRels
       where fakeSourceRelations = mapMaybe (toSourceRelation rootTableName) allRels -- see comment in toSourceRelation
-    readRequest = parse (pRequestSelect rootName) ("failed to parse select parameter <<"++selStr++">>") selStr
-    flts = mapM pRequestFilter filters
-    orders = iOrder apiRequest
-    ords = mapM pRequestOrder orders
 
 buildMutateRequest :: ApiRequest -> Either Text MutateRequest
-buildMutateRequest apiRequest =
-  mutateApiRequest
+buildMutateRequest apiRequest = case action of
+  ActionCreate -> Insert rootTableName <$> pure payload
+  ActionUpdate -> Update rootTableName <$> pure payload <*> filters
+  ActionDelete -> Delete rootTableName <$> filters
+  _        -> Left "Unsupported HTTP verb"
   where
     action = iAction apiRequest
-    target = iTarget apiRequest
     payload = fromJust $ iPayload apiRequest
     rootTableName = -- TODO: Make it safe
+      let target = iTarget apiRequest in
       case target of
         (TargetIdent (QualifiedIdentifier _ t) ) -> t
         _ -> undefined
-    mutateApiRequest = case action of
-      ActionCreate -> Insert rootTableName <$> pure payload
-      ActionUpdate -> Update rootTableName <$> pure payload <*> cond
-      ActionDelete -> Delete rootTableName <$> cond
-      _        -> Left "Unsupported HTTP verb"
-    mutateFilters = filter (not . ( '.' `elem` ) . fst) $ iFilters apiRequest -- update/delete filters can be only on the root table
-    cond = first formatParserError $ map snd <$> mapM pRequestFilter mutateFilters
+    filters = first formatParserError $ map snd <$> mapM pRequestFilter mutateFilters
+      where mutateFilters = filter (not . ( '.' `elem` ) . fst) $ iFilters apiRequest -- update/delete filters can be only on the root table
 
 addFilterToNode :: Filter -> ReadRequest -> ReadRequest
 addFilterToNode flt (Node (q@Select {flt_=flts}, i) f) = Node (q {flt_=flt:flts}, i) f
@@ -347,6 +378,12 @@ addOrderToNode o (Node (q,i) f) = Node (q{order=Just o}, i) f
 addOrder :: (Path, [OrderTerm]) -> ReadRequest -> ReadRequest
 addOrder = addProperty addOrderToNode
 
+addRangeToNode :: NonnegRange -> ReadRequest -> ReadRequest
+addRangeToNode r (Node (q,i) f) = Node (q{range_=r}, i) f
+
+addRange :: (Path, NonnegRange) -> ReadRequest -> ReadRequest
+addRange = addProperty addRangeToNode
+
 addProperty :: (a -> ReadRequest -> ReadRequest) -> (Path, a) -> ReadRequest -> ReadRequest
 addProperty f ([], a) n = f a n
 addProperty f (path, a) (Node rn forest) =

src/PostgREST/Parsers.hs

@@ -11,14 +11,14 @@ import           Data.Tree
 import           PostgREST.QueryBuilder        (operators)
 import           PostgREST.Types
 import           Text.ParserCombinators.Parsec hiding (many, (<|>))
-
+import           PostgREST.RangeQuery      (NonnegRange,allRange)
 
 pRequestSelect :: Text -> Parser ReadRequest
 pRequestSelect rootNodeName = do
   fieldTree <- pFieldForest
   return $ foldr treeEntry (Node (readQuery, (rootNodeName, Nothing, Nothing)) []) fieldTree
   where
-    readQuery = Select [] [rootNodeName] [] Nothing
+    readQuery = Select [] [rootNodeName] [] Nothing allRange
     treeEntry :: Tree SelectItem -> ReadRequest -> ReadRequest
     treeEntry (Node fld@((fn, _),_,alias) fldForest) (Node (q, i) rForest) =
       case fldForest of
@@ -26,7 +26,7 @@ pRequestSelect rootNodeName = do
         _  -> Node (q, i) newForest
           where
             newForest =
-              foldr treeEntry (Node (Select [] [fn] [] Nothing, (fn, Nothing, alias)) []) fldForest:rForest
+              foldr treeEntry (Node (Select [] [fn] [] Nothing allRange, (fn, Nothing, alias)) []) fldForest:rForest
 
 pRequestFilter :: (String, String) -> Either ParseError (Path, Filter)
 pRequestFilter (k, v) = (,) <$> path <*> (Filter <$> fld <*> op <*> val)
@@ -45,6 +45,12 @@ pRequestOrder (k, v) = (,) <$> path <*> ord
     path = fst <$> treePath
     ord = parse pOrder ("failed to parse order (" ++ v ++ ")") v
 
+pRequestRange :: (String, NonnegRange) -> Either ParseError (Path, NonnegRange)
+pRequestRange (k, v) = (,) <$> path <*> pure v
+  where
+    treePath = parse pTreePath ("failed to parser tree path (" ++ k ++ ")") k
+    path = fst <$> treePath
+
 ws :: Parser Text
 ws = cs <$> many (oneOf " \t")
 

src/PostgREST/QueryBuilder.hs

@@ -35,7 +35,7 @@ import qualified Hasql.Decoders          as HD
 import qualified Data.Aeson              as JSON
 import           Data.Int                (Int64)
 
-import           PostgREST.RangeQuery    (NonnegRange, rangeLimit, rangeOffset)
+import           PostgREST.RangeQuery    (NonnegRange, rangeLimit, rangeOffset, allRange)
 import           Control.Error           (note, fromMaybe)
 import           Data.Functor.Contravariant (contramap)
 import qualified Data.HashMap.Strict     as HM
@@ -96,14 +96,14 @@ encodeUniformObjs :: HE.Params UniformObjects
 encodeUniformObjs =
   contramap (JSON.Array . V.map JSON.Object . unUniformObjects) (HE.value HE.json)
 
-createReadStatement :: SqlQuery -> SqlQuery -> NonnegRange -> Bool -> Bool -> Bool ->
+createReadStatement :: SqlQuery -> SqlQuery -> Bool -> Bool -> Bool ->
                        H.Query () ResultsWithCount
-createReadStatement selectQuery countQuery range isSingle countTotal asCsv =
+createReadStatement selectQuery countQuery isSingle countTotal asCsv =
   unicodeStatement sql HE.unit decodeStandard True
  where
   sql = [qc|
       WITH {sourceCTEName} AS ({selectQuery}) SELECT {cols}
-      FROM ( SELECT * FROM {sourceCTEName} {limitF range}) t |]
+      FROM ( SELECT * FROM {sourceCTEName}) t |]
   countResultF = if countTotal then "("<>countQuery<>")" else "null"
   cols = intercalate ", " [
       countResultF <> " AS total_result_set",
@@ -260,7 +260,7 @@ pgFmtLit x =
 
 requestToCountQuery :: Schema -> DbRequest -> SqlQuery
 requestToCountQuery _ (DbMutate _) = undefined
-requestToCountQuery schema (DbRead (Node (Select _ _ conditions _, (mainTbl, _, _)) _)) =
+requestToCountQuery schema (DbRead (Node (Select _ _ conditions _ _, (mainTbl, _, _)) _)) =
  unwords [
    "SELECT pg_catalog.count(1)",
    "FROM ", fromQi $ QualifiedIdentifier schema mainTbl,
@@ -274,7 +274,7 @@ requestToCountQuery schema (DbRead (Node (Select _ _ conditions _, (mainTbl, _,
 requestToQuery :: Schema -> DbRequest -> SqlQuery
 requestToQuery _ (DbMutate (Insert _ (PayloadParseError _))) = undefined
 requestToQuery _ (DbMutate (Update _ (PayloadParseError _) _)) = undefined
-requestToQuery schema (DbRead (Node (Select colSelects tbls conditions ord, (nodeName, maybeRelation, _)) forest)) =
+requestToQuery schema (DbRead (Node (Select colSelects tbls conditions ord range, (nodeName, maybeRelation, _)) forest)) =
   query
   where
     -- TODO! the folloing helper functions are just to remove the "schema" part when the table is "source" which is the name
@@ -288,7 +288,8 @@ requestToQuery schema (DbRead (Node (Select colSelects tbls conditions ord, (nod
       "FROM ", intercalate ", " (map (fromQi . toQi) tbls),
       unwords joins,
       ("WHERE " <> intercalate " AND " ( map (pgFmtCondition qi ) conditions )) `emptyOnNull` conditions,
-      orderF (fromMaybe [] ord)
+      orderF (fromMaybe [] ord),
+      limitF range
       ]
     orderF ts =
         if null ts
@@ -408,7 +409,9 @@ locationF pKeys =
     ) <> ")"
 
 limitF :: NonnegRange -> SqlFragment
-limitF r  = "LIMIT " <> limit <> " OFFSET " <> offset
+limitF r  = if r == allRange
+  then ""
+  else "LIMIT " <> limit <> " OFFSET " <> offset
   where
     limit  = maybe "ALL" (cs . show) $ rangeLimit r
     offset = cs . show $ rangeOffset r

src/PostgREST/RangeQuery.hs

@@ -4,13 +4,14 @@ module PostgREST.RangeQuery (
 , rangeLimit
 , rangeOffset
 , restrictRange
+, rangeGeq
+, allRange
 , NonnegRange
 ) where
 
 
 import           Control.Applicative
 import           Network.HTTP.Types.Header
-import           PostgREST.Types           ()
 
 import qualified Data.ByteString.Char8     as BS
 import           Data.Ranged.Boundaries
@@ -34,18 +35,19 @@ rangeParse range = do
     Just parsedRange ->
       let [_, from, to] = readMaybe . cs <$> parsedRange
           lower         = fromMaybe emptyRange   (rangeGeq <$> from)
-          upper         = fromMaybe (rangeGeq 0) (rangeLeq <$> to) in
+          upper         = fromMaybe allRange (rangeLeq <$> to) in
       rangeIntersection lower upper
-    Nothing -> rangeGeq 0
+    Nothing -> allRange
 
 rangeRequested :: RequestHeaders -> NonnegRange
-rangeRequested = rangeParse . fromMaybe "" . lookup hRange
+rangeRequested headers = fromMaybe allRange $
+  rangeParse <$> lookup hRange headers
 
 restrictRange :: Maybe Integer -> NonnegRange -> NonnegRange
 restrictRange Nothing r = r
 restrictRange (Just limit) r =
-  rangeIntersection r $
-    Range BoundaryBelowAll (BoundaryAbove $ rangeOffset r + limit - 1)
+   rangeIntersection r $
+     Range BoundaryBelowAll (BoundaryAbove $ rangeOffset r + limit - 1)
 
 rangeLimit :: NonnegRange -> Maybe Integer
 rangeLimit range =
@@ -63,6 +65,9 @@ rangeGeq :: Integer -> NonnegRange
 rangeGeq n =
   Range (BoundaryBelow n) BoundaryAboveAll
 
+allRange :: NonnegRange
+allRange = rangeGeq 0
+
 rangeLeq :: Integer -> NonnegRange
 rangeLeq n =
   Range BoundaryBelowAll (BoundaryAbove n)

src/PostgREST/Types.hs

@@ -6,6 +6,7 @@ import           Data.Int             (Int32)
 import           Data.Text
 import           Data.Tree
 import qualified Data.Vector          as V
+import           PostgREST.RangeQuery (NonnegRange)
 
 data DbStructure = DbStructure {
   dbTables      :: [Table]
@@ -111,7 +112,7 @@ type Cast = Text
 type NodeName = Text
 type SelectItem = (Field, Maybe Cast, Maybe Alias)
 type Path = [Text]
-data ReadQuery = Select { select::[SelectItem], from::[TableName], flt_::[Filter], order::Maybe [OrderTerm] } deriving (Show, Eq)
+data ReadQuery = Select { select::[SelectItem], from::[TableName], flt_::[Filter], order::Maybe [OrderTerm], range_::NonnegRange } deriving (Show, Eq)
 data MutateQuery = Insert { in_::TableName, qPayload::Payload }
                  | Delete { in_::TableName, where_::[Filter] }
                  | Update { in_::TableName, qPayload::Payload, where_::[Filter] } deriving (Show, Eq)

test/Feature/QueryLimitedSpec.hs

@@ -5,7 +5,7 @@ import Test.Hspec.Wai
 import Test.Hspec.Wai.JSON
 import Network.HTTP.Types
 import Network.Wai.Test (SResponse(simpleHeaders, simpleStatus))
-
+import Text.Heredoc
 import SpecHelper
 import Network.Wai (Application)
 
@@ -15,15 +15,23 @@ spec =
     it "restricts results" $
       get "/items"
         `shouldRespondWith` ResponseMatcher {
-          matchBody    = Just [json| [{"id":1},{"id":2},{"id":3}] |]
+          matchBody    = Just [json| [{"id":1},{"id":2}] |]
         , matchStatus  = 206
-        , matchHeaders = ["Content-Range" <:> "0-2/15"]
+        , matchHeaders = ["Content-Range" <:> "0-1/15"]
         }
 
     it "respects additional client limiting" $ do
       r <- request methodGet  "/items"
-                   (rangeHdrs $ ByteRangeFromTo 0 1) ""
+                   (rangeHdrs $ ByteRangeFromTo 0 0) ""
       liftIO $ do
         simpleHeaders r `shouldSatisfy`
-          matchHeader "Content-Range" "0-1/15"
+          matchHeader "Content-Range" "0-0/15"
         simpleStatus r `shouldBe` partialContent206
+
+    it "limit works on all levels" $
+      get "/users?select=id,tasks{id}&order=id.asc&tasks.order=id.asc"
+        `shouldRespondWith` ResponseMatcher {
+          matchBody    = Just [str|[{"id":1,"tasks":[{"id":1},{"id":2}]},{"id":2,"tasks":[{"id":5},{"id":6}]}]|]
+        , matchStatus  = 206
+        , matchHeaders = ["Content-Range" <:> "0-1/3"]
+        }

test/Feature/RangeSpec.hs

@@ -9,6 +9,7 @@ import Network.Wai.Test (SResponse(simpleHeaders,simpleStatus))
 import qualified Data.ByteString.Lazy         as BL
 
 import SpecHelper
+import Text.Heredoc
 import Network.Wai (Application)
 
 defaultRange :: BL.ByteString
@@ -142,6 +143,50 @@ spec = do
             , matchHeaders = ["Content-Range" <:> "0-0/*"]
             }
 
+    context "with limit/offset parameters" $ do
+      it "no parameters return everything" $
+        get "/items?select=id&order=id.asc"
+          `shouldRespondWith` ResponseMatcher {
+            matchBody    = Just [str|[{"id":1},{"id":2},{"id":3},{"id":4},{"id":5},{"id":6},{"id":7},{"id":8},{"id":9},{"id":10},{"id":11},{"id":12},{"id":13},{"id":14},{"id":15}]|]
+          , matchStatus  = 200
+          , matchHeaders = ["Content-Range" <:> "0-14/15"]
+          }
+      it "top level limit with parameter" $
+        get "/items?select=id&order=id.asc&limit=3"
+          `shouldRespondWith` ResponseMatcher {
+            matchBody    = Just [str|[{"id":1},{"id":2},{"id":3}]|]
+          , matchStatus  = 206
+          , matchHeaders = ["Content-Range" <:> "0-2/15"]
+          }
+      it "headers override get parameters" $
+        request methodGet  "/items?select=id&order=id.asc&limit=3"
+                     (rangeHdrs $ ByteRangeFromTo 0 1) ""
+          `shouldRespondWith` ResponseMatcher {
+            matchBody    = Just [str|[{"id":1},{"id":2}]|]
+          , matchStatus  = 206
+          , matchHeaders = ["Content-Range" <:> "0-1/15"]
+          }
+
+      it "limit works on all levels" $
+        get "/clients?select=id,projects{id,tasks{id}}&order=id.asc&limit=1&projects.order=id.asc&projects.limit=1&projects.tasks.order=id.asc&projects.tasks.limit=2"
+          `shouldRespondWith` ResponseMatcher {
+            matchBody    = Just [str|[{"id":1,"projects":[{"id":1,"tasks":[{"id":1},{"id":2}]}]}]|]
+          , matchStatus  = 206
+          , matchHeaders = ["Content-Range" <:> "0-0/2"]
+          }
+
+      it "fails on offset specified below level 1" $
+        get "/clients?select=id,projects{id,tasks{id}}&projects.offset=2&projects.limit=1"
+          `shouldRespondWith` 400
+
+      it "limit and offset works on first level" $
+        get "/items?select=id&order=id.asc&limit=3&offset=2"
+          `shouldRespondWith` ResponseMatcher {
+            matchBody    = Just [str|[{"id":3},{"id":4},{"id":5}]|]
+          , matchStatus  = 206
+          , matchHeaders = ["Content-Range" <:> "2-4/15"]
+          }
+
     context "with range headers" $ do
 
       context "of acceptable range" $ do

test/SpecHelper.hs

@@ -27,7 +27,7 @@ testUnicodeCfg =
 
 testLtdRowsCfg :: AppConfig
 testLtdRowsCfg =
-  AppConfig testDbConn "postgrest_test_anonymous" "test" 3000 (secret "safe") 10 (Just 3) True
+  AppConfig testDbConn "postgrest_test_anonymous" "test" 3000 (secret "safe") 10 (Just 2) True
 
 setupDb :: IO ()
 setupDb = do