feature #7: add function "find_comments_by_parent"

src/main/resources/sql/functions/comment/find_comments_by_parent.sql

@@ -0,0 +1,26 @@
+create or replace function find_comments_by_parent(
+    _parent_id uuid,
+    "limit" int default 50,
+    "offset" int default 0,
+    out resource json,
+    out total int
+) language plpgsql as
+$$
+begin
+    select json_agg(t), (select count(id) from "comment" com where com.parents_ids @> array[_parent_id])
+    into resource, total
+    from (
+        select
+            com.*,
+            json_build_object('id', com.target_id) as target,
+            find_citizen_by_id(com.citizen_id) as citizen
+        from "comment" as com
+        where com.parents_ids @> array[_parent_id]
+        order by com.parents_ids nulls first, created_at desc,
+        com.created_at desc
+        limit "limit" offset "offset"
+    ) as t;
+end;
+$$;
+
+-- drop function if exists find_comments_by_parent(uuid, int, int);

src/test/sql/comment.sql

@@ -31,6 +31,7 @@ declare
     _selected_comments json;
     _selected_comments_total int;
     _find_comments_by_target_result json;
+    _find_comments_by_parent_result json;
 begin
     -- insert user for context
     select insert_user(created_user) into created_user;
@@ -110,6 +111,13 @@ begin
     assert (_find_comments_by_target_result#>>'{1,content}') = 'God not exist', 'the second content must contain "God not exist", "' || (_find_comments_by_target_result#>>'{1,content}') || '" returned';
     assert (_find_comments_by_target_result#>>'{2,content}') = 'are you really sure ?', 'the third content must contain "are you really sure ?", "' || (_find_comments_by_target_result#>>'{2,content}') || '" returned';
 
+    select resource into _find_comments_by_parent_result
+    from find_comments_by_parent((_find_comments_by_target_result#>>'{0,id}')::uuid);
+    assert json_array_length(_find_comments_by_parent_result) = 2,
+        'the result should contain 2 comment, ' || json_array_length(_find_comments_by_parent_result) || ' returned';
+    assert (_find_comments_by_parent_result#>>'{0,content}') = 'God not exist', 'the second content must contain "God not exist", "' || (_find_comments_by_parent_result#>>'{0,content}') || '" returned';
+    assert (_find_comments_by_parent_result#>>'{1,content}') = 'are you really sure ?', 'the third content must contain "are you really sure ?", "' || (_find_comments_by_parent_result#>>'{1,content}') || '" returned';
+
     -- delete comment and context
     delete from "comment";
     delete from article;