db/schema/000_immutable.sql
2023-06-10 17:57:23 -05:00

44 lines
2.5 KiB
PL/PgSQL

create function mark_columns_immutable(schema text, table_ text, columns text[])
returns void
language plpgsql
as $$
declare
col text;
qualified_name text := concat(schema, '.', table_);
do_table_immutable_columns text := concat('do_', table_, '_immutable_columns');
trigger_table_immutable_columns text := concat('trigger_', table_, '_immutable_columns');
create_do_table_immutable_columns text;
create_trigger_table_immutable_columns text;
begin
create_do_table_immutable_columns := concat( create_do_table_immutable_columns
, 'create function ', schema, '.', do_table_immutable_columns, E'() returns trigger language plpgsql as \$\$\n'
, E'begin\n'
, ' if OLD.', columns[1], ' <> NEW.', columns[1], E' then\n'
, E' raise exception \'', qualified_name, '.', columns[1], E' is immutable\' using errcode = \'restrict_violation\';\n'
);
foreach col in array columns[2:] loop
create_do_table_immutable_columns := concat( create_do_table_immutable_columns
, E' elsif OLD.', col, ' <> NEW.', col, E' then\n'
, E' raise exception \'', qualified_name, '.', col, E' is immutable\' using errcode = \'restrict_violation\';\n'
);
end loop;
create_do_table_immutable_columns := concat( create_do_table_immutable_columns
, E' end if;\n'
, E'\n'
, E' return NEW;\n'
, E'end;\n'
, E'\$\$;\n'
);
create_trigger_table_immutable_columns := concat( create_trigger_table_immutable_columns
, 'create trigger ', trigger_table_immutable_columns, E'\n'
, 'before update on ', qualified_name, E'\n'
, 'for each row execute function ', do_table_immutable_columns, '();'
);
execute create_do_table_immutable_columns;
execute create_trigger_table_immutable_columns;
end;
$$;