fix: Make recursive view parsing work with XMLTABLE + DEFAULT

CHANGELOG.md

@@ -12,6 +12,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
  - #2020, Execute deferred constraint triggers when using `Prefer: tx=rollback` - @wolfgangwalther
  - #2058, Return 204 No Content without Content-Type for PUT - @wolfgangwalther
  - #2077, Fix `is` not working with upper or mixed case values like `NULL, TrUe, FaLsE` - @steve-chavez
+ - #2024, Fix schema cache loading when views with XMLTABLE and DEFAULT are present - @wolfgangwalther
 
 ## [9.0.0] - 2021-11-25
 

src/PostgREST/DbStructure.hs

@@ -792,7 +792,6 @@ pfkSourceColumns cols =
             replace(
             replace(
             replace(
-            replace(
             regexp_replace(
             replace(
             replace(
@@ -803,6 +802,7 @@ pfkSourceColumns cols =
             replace(
             replace(
             replace(
+            replace(
             replace(
               view_definition::text,
             -- This conversion to json is heavily optimized for performance.
@@ -814,9 +814,15 @@ pfkSourceColumns cols =
             -- -----------------------------------------------
             -- pattern           | replacement         | flags
             -- -----------------------------------------------
+            -- `<>` in pg_node_tree is the same as `null` in JSON, but due to very poor performance of json_typeof
+            -- we need to make this an empty array here to prevent json_array_elements from throwing an error
+            -- when the targetList is null.
+            -- We'll need to put it first, to make the node protection below work for node lists that start with
+            -- null: `(<> ...`, too. This is the case for coldefexprs, when the first column does not have a default value.
+               '<>'              , '()'
             -- `,` is not part of the pg_node_tree format, but used in the regex.
             -- This removes all `,` that might be part of column names.
-               ','               , ''
+            ), ','               , ''
             -- The same applies for `{` and `}`, although those are used a lot in pg_node_tree.
             -- We remove the escaped ones, which might be part of column names again.
             ), E'\\{'            , ''
@@ -851,10 +857,6 @@ pfkSourceColumns cols =
             ), ')'               , ']'
             -- pg_node_tree has ` ` between list items, but JSON uses `,`
             ), ' '             , ','
-            -- `<>` in pg_node_tree is the same as `null` in JSON, but due to very poor performance of json_typeof
-            -- we need to make this an empty array here to prevent json_array_elements from throwing an error
-            -- when the targetList is null.
-            ), '<>'              , '[]'
           )::json as view_definition
         from views
       ),

test/fixtures/schema.sql

@@ -2462,3 +2462,21 @@ BEGIN
 
   INSERT INTO deferrable_unique_constraint VALUES (1), (1);
 END$$;
+
+-- This view is not used in any requests but just parsed by the pfkSourceColumns query.
+-- XMLTABLE is only supported from PG 10 on
+DO $do$
+BEGIN
+  IF current_setting('server_version_num')::INT >= 100000 THEN
+    CREATE VIEW test.xml AS
+    SELECT *
+      FROM (SELECT ''::xml AS data) _,
+           XMLTABLE(
+             ''
+             PASSING data
+             COLUMNS id int PATH '@id',
+                     premier_name text PATH 'PREMIER_NAME' DEFAULT 'not specified'
+           );
+  END IF;
+END
+$do$;