Add Preference-Applied header for POST upsert

- Ensure creating nothing on ignore-duplicates succeeds
- Refactor locationF query

src/PostgREST/ApiRequest.hs

@@ -116,8 +116,8 @@ userApiRequest schema req reqBody
       , iPreferRepresentation = representation
       , iPreferSingleObjectParameter = singleObject
       , iPreferCount = hasPrefer "count=exact"
-      , iPreferResolution = if hasPrefer "resolution=merge-duplicates" then Just MergeDuplicates
+      , iPreferResolution = if hasPrefer (show MergeDuplicates) then Just MergeDuplicates
-                            else if hasPrefer "resolution=ignore-duplicates" then Just IgnoreDuplicates
+                            else if hasPrefer (show IgnoreDuplicates) then Just IgnoreDuplicates
                             else Nothing
       , iFilters = filters
       , iLogic = [(toS k, toS $ fromJust v) | (k,v) <- qParams, isJust v, endingIn ["and", "or"] k ]

src/PostgREST/App.hs

@@ -157,10 +157,10 @@ app dbStructure proc conf apiRequest =
                  && iPreferRepresentation apiRequest == Full
                 then return $ singularityError (toInteger nRows)
                 else do
-                  let stm = createWriteStatement sq mq
+                  let pkCols = tablePKCols dbStructure tSchema tName
+                      stm = createWriteStatement sq mq
                         (contentType == CTSingularJSON) isSingle
-                        (contentType == CTTextCSV) (iPreferRepresentation apiRequest)
+                        (contentType == CTTextCSV) (iPreferRepresentation apiRequest) pkCols
-                        (tablePKCols dbStructure tSchema tName)
                   row <- H.query (toS pjRaw) stm
                   let (_, _, fs, body) = extractQueryResult row
                       headers = catMaybes [
@@ -172,6 +172,9 @@ app dbStructure proc conf apiRequest =
                             else Nothing
                         , Just . contentRangeH 1 0 $
                             toInteger <$> if shouldCount then Just nRows else Nothing
+                        , if null pkCols
+                            then Nothing
+                            else (\x -> ("Preference-Applied", show x)) <$> iPreferResolution apiRequest
                         ]
 
                   return . responseLBS status201 headers $

src/PostgREST/QueryBuilder.hs

@@ -121,7 +121,7 @@ createWriteStatement selectQuery mutateQuery wantSingle wantHdrs asCsv rep pKeys
       "'' AS total_result_set", -- when updateing it does not make sense
       "pg_catalog.count(_postgrest_t) AS page_total",
       if wantHdrs
-         then locationF pKeys
+         then "coalesce(" <> locationF pKeys <> ", " <> noLocationF <> ")"
          else noLocationF <> " AS header",
       if rep == Full
          then bodyF <> " AS body"
@@ -278,7 +278,7 @@ requestToQuery schema isParent (DbRead (Node (Select colSelects tbls logicForest
 requestToQuery schema _ (DbMutate (Insert mainTbl pkCols p@(PayloadJSON _ pType pKeys) onConflct logicForest returnings)) =
   unwords [
     ("WITH " <> ignoredBody) `emptyOnFalse` not payloadIsEmpty,
-    "INSERT INTO ", fromQi qi, if payloadIsEmpty then " " else "(" <> cols <> ") ",
+    "INSERT INTO ", fromQi qi, if payloadIsEmpty then " " else "(" <> cols <> ")",
     case (pType, payloadIsEmpty) of
       (PJArray _, True) -> "SELECT null WHERE false"
       (PJObject, True)  -> "DEFAULT VALUES"
@@ -369,16 +369,12 @@ asBinaryF :: FieldName -> SqlFragment
 asBinaryF fieldName = "coalesce(string_agg(_postgrest_t." <> pgFmtIdent fieldName <> ", ''), '')"
 
 locationF :: [Text] -> SqlFragment
-locationF pKeys =
+locationF pKeys = [qc|(
-    "(" <>
+  WITH data AS (SELECT row_to_json(_) AS row FROM {sourceCTEName} AS _ LIMIT 1)
-    " WITH s AS (SELECT row_to_json(ss) as r from " <> sourceCTEName <> " as ss  limit 1)" <>
+  SELECT array_agg(json_data.key || '=' || coalesce('eq.' || json_data.value, 'is.null'))
-    " SELECT array_agg(json_data.key || '=' || coalesce('eq.' || json_data.value, 'is.null'))" <>
+  FROM data CROSS JOIN json_each_text(data.row) AS json_data
-    " FROM s, json_each_text(s.r) AS json_data" <>
+  {("WHERE json_data.key IN ('" <> intercalate "','" pKeys <> "')") `emptyOnFalse` null pKeys}
-    (
+)|]
-      if null pKeys
-      then ""
-      else " WHERE json_data.key IN ('" <> intercalate "','" pKeys <> "')"
-    ) <> ")"
 
 limitF :: NonnegRange -> SqlFragment
 limitF r  = if r == allRange

src/PostgREST/Types.hs

@@ -26,7 +26,10 @@ data ApiRequestError = ActionInappropriate
                      | InvalidFilters
                      deriving (Show, Eq)
 
-data PreferResolution = MergeDuplicates | IgnoreDuplicates deriving (Eq, Show)
+data PreferResolution = MergeDuplicates | IgnoreDuplicates deriving Eq
+instance Show PreferResolution where
+  show MergeDuplicates  = "resolution=merge-duplicates"
+  show IgnoreDuplicates = "resolution=ignore-duplicates"
 
 data DbStructure = DbStructure {
   dbTables      :: [Table]

test/Feature/UpsertSpec.hs

@@ -28,7 +28,7 @@ spec =
               { "name": "C", "rank": 1 }
             ]|]
             { matchStatus = 201
-            , matchHeaders = [matchContentTypeJson]
+            , matchHeaders = ["Preference-Applied" <:> "resolution=merge-duplicates", matchContentTypeJson]
             }
 
         it "INSERTs and UPDATEs row on composite pk conflict" $
@@ -41,7 +41,7 @@ spec =
               { "first_name": "Peter S.", "last_name": "Yang", "salary": "$42,000.00", "company": null, "occupation": null }
             ]|]
             { matchStatus = 201
-            , matchHeaders = [matchContentTypeJson]
+            , matchHeaders = ["Preference-Applied" <:> "resolution=merge-duplicates", matchContentTypeJson]
             }
 
       context "when Prefer: resolution=ignore-duplicates is specified" $ do
@@ -54,7 +54,7 @@ spec =
               { "name": "PHP", "rank": 9 }
             ]|]
             { matchStatus = 201
-            , matchHeaders = [matchContentTypeJson]
+            , matchHeaders = ["Preference-Applied" <:> "resolution=ignore-duplicates", matchContentTypeJson]
             }
 
         it "INSERTs and ignores rows on composite pk conflict" $
@@ -66,25 +66,40 @@ spec =
               { "first_name": "Sara M.", "last_name": "Torpey", "salary": "$60,000.00", "company": "Burstein-Applebee", "occupation": "Soil scientist" }
             ]|]
             { matchStatus = 201
-            , matchHeaders = [matchContentTypeJson]
+            , matchHeaders = ["Preference-Applied" <:> "resolution=ignore-duplicates", matchContentTypeJson]
             }
 
       it "succeeds if the table has only PK cols and no other cols" $ do
         request methodPost "/only_pk" [("Prefer", "return=representation"), ("Prefer", "resolution=ignore-duplicates")]
           [json|[ { "id": 1 }, { "id": 2 }, { "id": 3} ]|]
           `shouldRespondWith`
-          [json|[ { "id": 3} ]|] { matchStatus = 201 , matchHeaders = [matchContentTypeJson] }
+          [json|[ { "id": 3} ]|]
+          { matchStatus = 201 ,
+            matchHeaders = ["Preference-Applied" <:> "resolution=ignore-duplicates",
+            matchContentTypeJson] }
+
         request methodPost "/only_pk" [("Prefer", "return=representation"), ("Prefer", "resolution=merge-duplicates")]
           [json|[ { "id": 1 }, { "id": 2 }, { "id": 4} ]|]
           `shouldRespondWith`
-          [json|[ { "id": 1 }, { "id": 2 }, { "id": 4} ]|] { matchStatus = 201 , matchHeaders = [matchContentTypeJson] }
+          [json|[ { "id": 1 }, { "id": 2 }, { "id": 4} ]|]
+          { matchStatus = 201 ,
+            matchHeaders = ["Preference-Applied" <:> "resolution=merge-duplicates",
+            matchContentTypeJson] }
 
-      it "succeeds and ignores the Prefer: resolution header if the table has no PK" $
+      it "succeeds and ignores the Prefer: resolution header(no Preference-Applied present) if the table has no PK" $
         request methodPost "/no_pk" [("Prefer", "return=representation"), ("Prefer", "resolution=merge-duplicates")]
           [json|[ { "a": "1", "b": "0" } ]|]
           `shouldRespondWith`
           [json|[ { "a": "1", "b": "0" } ]|] { matchStatus = 201 , matchHeaders = [matchContentTypeJson] }
 
+      it "succeeds if not a single resource is created" $ do
+        request methodPost "/tiobe_pls" [("Prefer", "return=representation"), ("Prefer", "resolution=ignore-duplicates")]
+          [json|[ { "name": "Java", "rank": 1 } ]|] `shouldRespondWith`
+          [json|[]|] { matchStatus = 201 , matchHeaders = [matchContentTypeJson] }
+        request methodPost "/tiobe_pls" [("Prefer", "return=representation"), ("Prefer", "resolution=ignore-duplicates")]
+          [json|[ { "name": "Java", "rank": 1 }, { "name": "C", "rank": 2 } ]|] `shouldRespondWith`
+          [json|[]|] { matchStatus = 201 , matchHeaders = [matchContentTypeJson] }
+
     context "with PUT" $ do
       context "Restrictions" $ do
         it "fails if Range is specified" $