Allow returning XML from single-column queries

test/spec/Feature/Query/QuerySpec.hs

@@ -1010,6 +1010,14 @@ spec actualPgVersion = do
         , matchHeaders = ["Content-Type" <:> "text/plain; charset=utf-8"]
         }
 
+    it "can get raw xml output with Accept: text/xml" $
+      request methodGet "/xmltest?select=xml" (acceptHdrs "text/xml") ""
+        `shouldRespondWith`
+        "<myxml>foo</myxml>bar<foobar><baz/></foobar>"
+        { matchStatus = 200
+        , matchHeaders = ["Content-Type" <:> "text/xml; charset=utf-8"]
+        }
+
     it "fails if a single column is not selected" $ do
       request methodGet "/images?select=img,name&name=eq.A.png" (acceptHdrs "application/octet-stream") ""
         `shouldRespondWith`

test/spec/fixtures/privileges.sql

@@ -178,6 +178,7 @@ GRANT ALL ON TABLE
     , limited_delete_items_wnonuniq_view
     , limited_delete_items_cpk_view
     , limited_update_items_cpk_view
+    , xmltest
 TO postgrest_test_anonymous;
 
 GRANT INSERT ON TABLE insertonly TO postgrest_test_anonymous;

test/spec/fixtures/schema.sql

@@ -2583,3 +2583,13 @@ select $$
   </body>
 </html>$$::pg_catalog.xml;
 $_$;
+
+CREATE TABLE test.xmltest (
+    id integer primary key,
+    xml pg_catalog.xml NOT NULL
+);
+
+INSERT INTO test.xmltest VALUES
+(1, '<myxml>foo</myxml>'),
+(2, 'bar'),
+(3, '<foobar><baz/></foobar>');