Merge pull request #400 from diogob/order_by_computed_column

Order by computed column

CHANGELOG.md

@@ -9,6 +9,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Miscalculation of time used for expiring tokens - @calebmer
 - Remove bcrypt dependency to fix Windows build - @begriffs
 
+### Added
+- Allow order by computed columns - @diogob
+
 ## [0.3.0.1] - 2015-11-27
 
 ### Fixed

docs/api/reading.md

@@ -171,6 +171,11 @@ If you care where nulls are sorted, add `nullsfirst` or `nullslast`:
 GET /people?order=age.nullsfirst
 ```
 
+You can also use [computed
+columns](http://www.postgresql.org/docs/current/interactive/xfunc-sql.html#XFUNC-SQL-COMPOSITE-FUNCTIONS)
+to order the results, even though the computed
+columns will not appear in the output.
+
 ### Limiting and Pagination
 
 #### Pagination by Limit-Offset

src/PostgREST/QueryBuilder.hs

@@ -200,6 +200,17 @@ requestToQuery schema (DbRead (Node (Select colSelects tbls conditions ord, (mai
       ("WHERE " <> intercalate " AND " ( map (pgFmtCondition qi ) conditions )) `emptyOnNull` conditions,
       orderF (fromMaybe [] ord)
       ]
+    orderF ts =
+        if null ts
+            then ""
+            else "ORDER BY " <> clause
+        where
+            clause = intercalate "," (map queryTerm ts)
+            queryTerm :: OrderTerm -> Text
+            queryTerm t = " "
+                <> cs (pgFmtColumn qi $ otTerm t) <> " "
+                <> (cs.show) (otDirection t) <> " "
+                <> maybe "" (cs.show) (otNullOrder t) <> " "
     (withs, selects) = foldr getQueryParts ([],[]) forest
     getQueryParts :: Tree ReadNode -> ([(SqlFragment, Text)], [SqlFragment]) -> ([(SqlFragment,Text)], [SqlFragment])
     getQueryParts (Node n@(_, (table, Just (Relation {relType=Child}))) forst) (w,s) = (w,sel:s)
@@ -337,19 +348,6 @@ getJoinConditions (Relation t cols ft fcs typ lt lc1 lc2) =
 emptyOnNull :: Text -> [a] -> Text
 emptyOnNull val x = if null x then "" else val
 
-orderF :: [OrderTerm] -> SqlFragment
-orderF ts =
-  if null ts
-    then ""
-    else "ORDER BY " <> clause
-  where
-    clause = intercalate "," (map queryTerm ts)
-    queryTerm :: OrderTerm -> Text
-    queryTerm t = " "
-           <> cs (pgFmtIdent $ otTerm t) <> " "
-           <> (cs.show) (otDirection t) <> " "
-           <> maybe "" (cs.show) (otNullOrder t) <> " "
-
 insertableValue :: JSON.Value -> SqlFragment
 insertableValue JSON.Null = "null"
 insertableValue v = (<> "::unknown") . pgFmtLit $ unquoted v

test/Feature/QuerySpec.hs

@@ -130,7 +130,11 @@ spec =
         [json| [{"text_search_vector":"'baz':1 'qux':2"}] |]
 
     it "matches with computed column" $
-      get "/items?always_true=eq.true" `shouldRespondWith`
+      get "/items?always_true=eq.true&order=id.asc" `shouldRespondWith`
+        [json| [{"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}] |]
+
+    it "order by computed column" $
+      get "/items?order=anti_id.desc" `shouldRespondWith`
         [json| [{"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}] |]
 
     it "matches filtering nested items" $

test/fixtures/schema.sql

@@ -462,6 +462,11 @@ CREATE FUNCTION public.always_true(test.items) RETURNS boolean
 
 ALTER FUNCTION public.always_true(test.items) OWNER TO postgrest_test;
 
+CREATE FUNCTION public.anti_id(test.items) RETURNS bigint
+LANGUAGE sql STABLE
+AS $$ SELECT $1.id * -1 $$;
+
+ALTER FUNCTION public.anti_id(test.items) OWNER TO postgrest_test;
 
 
 ALTER TABLE ONLY authors_only