Polymorphism

Subtopics

EdgeQL Tutorial

Polymorphism

In our schema, the abstract type Content is extended by the concrete types Movie and Show, making Content polymorphic: it's a single interface to more than one type.

To make a polymorphic query inside a shape, you can use the is keyword followed by a concrete type, all inside square brackets. For example, to get all the different Content objects starring a particular actor, try:

Input

Run

select Content {
  title,
  [is Movie].release_year,
  [is Show].num_seasons,
}
filter .actors.name = 'Patrick Stewart';

select Content {
  title,
  [is Movie].release_year,
  [is Show].num_seasons,
}
filter .actors.name = 'Patrick Stewart';

Output Objects

Press the 'Run' button to evaluate the input

Finally, all the data necessary to render a user's page with their watchlist organized by title and release_year as well as the featured suggestions from above can be packed into a single query:

Input

Run

select Account {
  username,
  watchlist: {
    title,
    [is Movie].release_year,
    [is Show].num_seasons,
  }
  # We'll order by the first word of the title.
  order by re_match(r'\w+', .title)[0] asc
  # We can refer to release_year here because we've defined
  # how that should be included in the shape.
        then .release_year desc,
  suggested := (
    select Content {
      title,
      [is Movie].release_year,
      [is Show].num_seasons,
    }
    filter .actors.name = 'Patrick Stewart'
  ),
}
filter .username = 'Alice';

select Account {
  username,
  watchlist: {
    title,
    [is Movie].release_year,
    [is Show].num_seasons,
  }
  # We'll order by the first word of the title.
  order by re_match(r'\w+', .title)[0] asc
  # We can refer to release_year here because we've defined
  # how that should be included in the shape.
        then .release_year desc,
  suggested := (
    select Content {
      title,
      [is Movie].release_year,
      [is Show].num_seasons,
    }
    filter .actors.name = 'Patrick Stewart'
  ),
}
filter .username = 'Alice';

Output Objects

Press the 'Run' button to evaluate the input

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