feature #4: create function for article

implement generate_version_number()

resources/functions/article/upsert_article.sql

@@ -0,0 +1,23 @@
+create or replace procedure upsert_article(inout resource json)
+    language plpgsql as
+$$
+declare
+    new_id uuid;
+begin
+    insert into article (version_id, created_by_id, title, annonymous, content, description, tags)
+    select
+       version_id,
+       (resource#>>'{created_by, id}')::uuid,
+       title,
+       annonymous,
+       content,
+       description,
+       tags
+    from json_populate_record(null::article, resource)
+    returning id into new_id;
+
+    select find_article_by_id(new_id) into resource;
+end;
+$$;
+
+-- drop procedure if exists upsert_article(inout json);