feat: add limited delete

CHANGELOG.md

@@ -18,7 +18,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
    + #1689, Add the ability to run without `db-anon-role` disabling anonymous access. - @wolfgangwalther
  - #1543, Allow access to fields of composite types in select=, order= and filters through JSON operators -> and ->>. - @wolfgangwalther
  - #2075, Allow access to array items in ?select=, ?order= and filters through JSON operators -> and ->>. - @wolfgangwalther
- - #2156, Allow applying `limit/offset` to UPDATE to only affect a subset of rows - @steve-chavez
+ - #2156, Allow applying `limit/offset` to UPDATE/DELETE to only affect a subset of rows - @steve-chavez
    + Uses the table primary key, so it needs a select privilege on the primary key columns
    + If no primary key is available, it will fallback to using the "ctid" system column(will also require a select privilege on it)
    + Will work on views if the PK(or "ctid") is present on its SELECT clause
@@ -47,7 +47,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
  - #2001, Return 204 No Content without Content-Type for RPCs returning VOID - @wolfgangwalther
    + Previously, those RPCs would return "null" as a body with Content-Type: application/json.
- - #2156, `limit/offset` now limits the affected rows on UPDATE  - @steve-chavez
+ - #2156, `limit/offset` now limits the affected rows on UPDATE/DELETE  - @steve-chavez
    + Previously, `limit/offset` only limited the returned rows but not the actual updated rows
 
 ## [9.0.0] - 2021-11-25

src/PostgREST/Query/QueryBuilder.hs

@@ -125,13 +125,13 @@ mutateRequestToQuery (Update mainQi uCols body logicForest (range, rangeId) retu
     "WITH " <> normalizedBody body <> ", " <>
     "pgrst_update_body AS (SELECT * FROM json_populate_recordset (null::" <> mainTbl <> " , " <> SQL.sql selectBody <> " ) LIMIT 1), " <>
     "pgrst_affected_rows AS (" <>
-      "SELECT " <> SQL.sql _rangeId <> " FROM " <> mainTbl <>
+      "SELECT " <> SQL.sql rangeIdF <> " FROM " <> mainTbl <>
        whereLogic <> " " <>
-      "ORDER BY " <> SQL.sql _rangeId <> " " <> limitOffsetF range <>
+      "ORDER BY " <> SQL.sql rangeIdF <> " " <> limitOffsetF range <>
     ") " <>
     "UPDATE " <> mainTbl <> " SET " <> SQL.sql rangeCols <>
     "FROM pgrst_affected_rows " <>
-    "WHERE " <> SQL.sql whereRangeId <> " " <>
+    "WHERE " <> SQL.sql whereRangeIdF <> " " <>
     SQL.sql (returningF mainQi returnings)
 
   where
@@ -140,14 +140,29 @@ mutateRequestToQuery (Update mainQi uCols body logicForest (range, rangeId) retu
     emptyBodyReturnedColumns = if null returnings then "NULL" else BS.intercalate ", " (pgFmtColumn (QualifiedIdentifier mempty $ qiName mainQi) <$> returnings)
     nonRangeCols = BS.intercalate ", " (pgFmtIdent <> const " = _." <> pgFmtIdent <$> S.toList uCols)
     rangeCols = BS.intercalate ", " ((\col -> pgFmtIdent col <> " = (SELECT " <> pgFmtIdent col <> " FROM pgrst_update_body) ") <$> S.toList uCols)
-    _rangeId = if null rangeId then pgFmtColumn mainQi "ctid" else BS.intercalate ", " (pgFmtColumn mainQi <$> rangeId)
+    (whereRangeIdF, rangeIdF) = mutRangeF mainQi rangeId
-    whereRangeId = BS.intercalate " AND " $
-      (\col -> pgFmtColumn mainQi col <> " = " <> pgFmtColumn (QualifiedIdentifier mempty "pgrst_affected_rows") col) <$> (if null rangeId then ["ctid"] else rangeId)
 
-mutateRequestToQuery (Delete mainQi logicForest returnings) =
+mutateRequestToQuery (Delete mainQi logicForest (range, rangeId) returnings)
-  "DELETE FROM " <> SQL.sql (fromQi mainQi) <> " " <>
+  | range == allRange =
-  (if null logicForest then mempty else "WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree mainQi) logicForest)) <> " " <>
+    "DELETE FROM " <> SQL.sql (fromQi mainQi) <> " " <>
-  SQL.sql (returningF mainQi returnings)
+    whereLogic <> " " <>
+    SQL.sql (returningF mainQi returnings)
+
+  | otherwise =
+    "WITH " <>
+    "pgrst_affected_rows AS (" <>
+      "SELECT " <> SQL.sql rangeIdF <> " FROM " <> SQL.sql (fromQi mainQi) <>
+       whereLogic <> " " <>
+      "ORDER BY " <> SQL.sql rangeIdF <> " " <> limitOffsetF range <>
+    ") " <>
+    "DELETE FROM " <> SQL.sql (fromQi mainQi) <> " " <>
+    "USING pgrst_affected_rows " <>
+    "WHERE " <> SQL.sql whereRangeIdF <> " " <>
+    SQL.sql (returningF mainQi returnings)
+
+  where
+    whereLogic = if null logicForest then mempty else " WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree mainQi <$> logicForest)
+    (whereRangeIdF, rangeIdF) = mutRangeF mainQi rangeId
 
 requestToCallProcQuery :: CallRequest -> SQL.Snippet
 requestToCallProcQuery (FunctionCall qi params args returnsScalar multipleCall returnings) =

src/PostgREST/Query/SqlFragment.hs

@@ -17,6 +17,7 @@ module PostgREST.Query.SqlFragment
   , fromQi
   , limitOffsetF
   , locationF
+  , mutRangeF
   , normalizedBody
   , pgFmtColumn
   , pgFmtIdent
@@ -334,3 +335,12 @@ unknownLiteral = unknownEncoder . encodeUtf8
 intercalateSnippet :: ByteString -> [SQL.Snippet] -> SQL.Snippet
 intercalateSnippet _ [] = mempty
 intercalateSnippet frag snippets = foldr1 (\a b -> a <> SQL.sql frag <> b) snippets
+
+-- the "ctid" system column is always available to tables
+mutRangeF :: QualifiedIdentifier -> [FieldName] -> (SqlFragment, SqlFragment)
+mutRangeF mainQi rangeId = (
+    BS.intercalate " AND " $
+          (\col -> pgFmtColumn mainQi col <> " = " <> pgFmtColumn (QualifiedIdentifier mempty "pgrst_affected_rows") col) <$>
+          (if null rangeId then ["ctid"] else rangeId)
+  , if null rangeId then pgFmtColumn mainQi "ctid" else BS.intercalate ", " (pgFmtColumn mainQi <$> rangeId)
+  )

src/PostgREST/Request/DbRequestBuilder.hs

@@ -332,7 +332,7 @@ mutateRequest mutation schema tName ApiRequest{..} pkCols readReq = mapLeft ApiR
           then Right $ Insert qi iColumns body (Just (MergeDuplicates, pkCols)) combinedLogic returnings
         else
           Left InvalidFilters
-    MutationDelete -> Right $ Delete qi combinedLogic returnings
+    MutationDelete -> Right $ Delete qi combinedLogic (iTopLevelRange, pkCols) returnings
   where
     confCols = fromMaybe pkCols qsOnConflict
     QueryParams.QueryParams{..} = iQueryParams

src/PostgREST/Request/Types.hs

@@ -141,6 +141,7 @@ data MutateQuery
   | Delete
       { in_       :: QualifiedIdentifier
       , where_    :: [LogicTree]
+      , mutRange  :: (NonnegRange, [FieldName])
       , returning :: [FieldName]
       }
 

test/spec/Feature/Query/DeleteSpec.hs

@@ -115,3 +115,164 @@ spec =
             { matchStatus = 204
             , matchHeaders = [matchHeaderAbsent hContentType]
             }
+
+    context "limited delete" $ do
+      it "works with the limit and offset query params" $ do
+        get "/limited_delete_items"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 2, "name": "item-2" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodDelete "/limited_delete_items?limit=1&offset=1"
+            [("Prefer", "tx=commit")]
+            mempty
+          `shouldRespondWith`
+            ""
+            { matchStatus  = 204
+            , matchHeaders = [ matchHeaderAbsent hContentType
+                             , "Preference-Applied" <:> "tx=commit" ]
+            }
+
+        get "/limited_delete_items?order=id"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodPost "/rpc/reset_limited_items"
+          [("Prefer", "tx=commit")]
+          [json| {"tbl_name": "limited_delete_items"} |]
+          `shouldRespondWith` ""
+          { matchStatus  = 204 }
+
+      it "works with the limit query param plus a filter" $ do
+        get "/limited_delete_items"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 2, "name": "item-2" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodDelete "/limited_delete_items?limit=1&id=gt.1"
+            [("Prefer", "tx=commit")]
+            mempty
+          `shouldRespondWith`
+            ""
+            { matchStatus  = 204
+            , matchHeaders = [ matchHeaderAbsent hContentType
+                             , "Preference-Applied" <:> "tx=commit" ]
+            }
+
+        get "/limited_delete_items?order=id"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodPost "/rpc/reset_limited_items"
+          [("Prefer", "tx=commit")]
+          [json| {"tbl_name": "limited_delete_items"} |]
+          `shouldRespondWith` ""
+          { matchStatus  = 204 }
+
+      it "works on a table with a composite pk" $ do
+        get "/limited_delete_items_cpk"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 2, "name": "item-2" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodDelete "/limited_delete_items_cpk?limit=1&offset=1"
+            [("Prefer", "tx=commit")]
+            mempty
+          `shouldRespondWith`
+            ""
+            { matchStatus  = 204
+            , matchHeaders = [ matchHeaderAbsent hContentType
+                             , "Preference-Applied" <:> "tx=commit" ]
+            }
+
+        get "/limited_delete_items_cpk"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodPost "/rpc/reset_limited_items"
+          [("Prefer", "tx=commit")]
+          [json| {"tbl_name": "limited_delete_items_cpk"} |]
+          `shouldRespondWith` ""
+          { matchStatus  = 204 }
+
+      it "works with views with an inferred pk" $ do
+        get "/limited_delete_items_view"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 2, "name": "item-2" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodDelete "/limited_delete_items_view?limit=1&offset=1"
+            [("Prefer", "tx=commit")]
+            mempty
+          `shouldRespondWith`
+            ""
+            { matchStatus  = 204
+            , matchHeaders = [ matchHeaderAbsent hContentType
+                             , "Preference-Applied" <:> "tx=commit" ]
+            }
+
+        get "/limited_delete_items_view"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodPost "/rpc/reset_limited_items"
+          [("Prefer", "tx=commit")]
+          [json| {"tbl_name": "limited_delete_items_view"} |]
+          `shouldRespondWith` ""
+          { matchStatus  = 204 }
+
+      it "works on a table without a pk" $ do
+        get "/limited_delete_items_no_pk"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 2, "name": "item-2" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodDelete "/limited_delete_items_no_pk?limit=1&offset=1"
+            [("Prefer", "tx=commit")]
+            mempty
+          `shouldRespondWith`
+            ""
+            { matchStatus  = 204
+            , matchHeaders = [ matchHeaderAbsent hContentType
+                             , "Preference-Applied" <:> "tx=commit" ]
+            }
+
+        get "/limited_delete_items_no_pk"
+          `shouldRespondWith`
+            [json|[
+              { "id": 1, "name": "item-1" }
+            , { "id": 3, "name": "item-3" }
+            ]|]
+
+        request methodPost "/rpc/reset_limited_items"
+          [("Prefer", "tx=commit")]
+          [json| {"tbl_name": "limited_delete_items_no_pk"} |]
+          `shouldRespondWith` ""
+          { matchStatus  = 204 }

test/spec/fixtures/data.sql

@@ -737,11 +737,20 @@ INSERT INTO test.fav_numbers VALUES (ROW(0.5, 0.5), 'A'),  (ROW(0.6, 0.6), 'B');
 TRUNCATE TABLE test.arrays CASCADE;
 INSERT INTO test.arrays VALUES (0, '{1,2,3}', '{{1,2,3},{4,5,6},{7,8,9}}'), (1, '{11,12,13}', '{{11,12,13},{14,15,16},{17,18,19}}');
 
-TRUNCATE TABLE test.limited_updated_items CASCADE;
+TRUNCATE TABLE test.limited_update_items CASCADE;
-INSERT INTO test.limited_updated_items VALUES (1, 'item-1'), (2, 'item-2'), (3, 'item-3');
+INSERT INTO test.limited_update_items VALUES (1, 'item-1'), (2, 'item-2'), (3, 'item-3');
 
-TRUNCATE TABLE test.limited_updated_items_cpk CASCADE;
+TRUNCATE TABLE test.limited_update_items_cpk CASCADE;
-INSERT INTO test.limited_updated_items_cpk VALUES (1, 'item-1'), (2, 'item-2'), (3, 'item-3');
+INSERT INTO test.limited_update_items_cpk VALUES (1, 'item-1'), (2, 'item-2'), (3, 'item-3');
 
-TRUNCATE TABLE test.limited_updated_items_no_pk CASCADE;
+TRUNCATE TABLE test.limited_update_items_no_pk CASCADE;
-INSERT INTO test.limited_updated_items_no_pk VALUES (1, 'item-1'), (2, 'item-2'), (3, 'item-3');
+INSERT INTO test.limited_update_items_no_pk VALUES (1, 'item-1'), (2, 'item-2'), (3, 'item-3');
+
+TRUNCATE TABLE test.limited_delete_items CASCADE;
+INSERT INTO test.limited_delete_items VALUES (1, 'item-1'), (2, 'item-2'), (3, 'item-3');
+
+TRUNCATE TABLE test.limited_delete_items_cpk CASCADE;
+INSERT INTO test.limited_delete_items_cpk VALUES (1, 'item-1'), (2, 'item-2'), (3, 'item-3');
+
+TRUNCATE TABLE test.limited_delete_items_no_pk CASCADE;
+INSERT INTO test.limited_delete_items_no_pk VALUES (1, 'item-1'), (2, 'item-2'), (3, 'item-3');

test/spec/fixtures/privileges.sql

@@ -163,10 +163,14 @@ GRANT ALL ON TABLE
     , clientinfo
     , contact
     , chores
-    , limited_mut_items
+    , limited_update_items
-    , limited_mut_items_cpk
+    , limited_update_items_cpk
-    , limited_mut_items_no_pk
+    , limited_update_items_no_pk
-    , limited_mut_items_view
+    , limited_update_items_view
+    , limited_delete_items
+    , limited_delete_items_cpk
+    , limited_delete_items_no_pk
+    , limited_delete_items_view
 TO postgrest_test_anonymous;
 
 GRANT INSERT ON TABLE insertonly TO postgrest_test_anonymous;

test/spec/fixtures/schema.sql

@@ -2488,6 +2488,25 @@ create table limited_update_items_no_pk(
 create view limited_update_items_view as
 select * from limited_update_items;
 
+create table limited_delete_items(
+  id int primary key
+, name text
+);
+
+create table limited_delete_items_cpk(
+  id int
+, name text
+, primary key (id, name)
+);
+
+create table limited_delete_items_no_pk(
+  id int
+, name text
+);
+
+create view limited_delete_items_view as
+select * from limited_delete_items;
+
 create function reset_limited_items(tbl_name text default '') returns void as $_$ begin
   execute format(
   $$