Chapter 9: Errors that didn't occur, and a missing assert_single

[stevechen]

1. this code

for character_name in {'John Seward', 'Quincey Morris', 'Arthur Holmwood'}
select character_name ++ ' is great';

was suppose to generate error according to the description, but it worked…

3. this code didn't work:

for character_name in {'John Seward', 'Quincey Morris', 'Arthur Holmwood'}
union (
  insert NPC {
    name := character_name,
    places_visited := (select City filter .name = 'London'),
    lover := (select Person filter .name = 'Lucy Westenra'),
  }
);

It needs a assert_single on lover:

for character_name in {'John Seward', 'Quincey Morris', 'Arthur Holmwood'}
union (
  insert NPC {
    name := character_name,
    places_visited := (select City filter .name = 'London'),
    lover := assert_single((select Person filter .name = 'Lucy Westenra')),
  }
);