Polymorphism

Subtopics

EdgeQL Tutorial

Polymorphism

You can also make polymorphic queries using shapes. For example, to get all the different media from a particular user, try:

Input

SELECT Media {
    hashtags,
    type := .__type__.name,
    [IS Text].title,
    [IS Text].body,
    [IS UploadedMedia].uri,
}
FILTER .author.email = 'dana@tutorial.com';

SELECT Media {
    hashtags,
    type := .__type__.name,
    [IS Text].title,
    [IS Text].body,
    [IS UploadedMedia].uri,
}
FILTER .author.email = 'dana@tutorial.com';

Run

Output

Press the 'Run' button to evaluate the input

Combining more of the things covered earlier in this tutorial you can make a query to fetch the most recent media in a user's feed like this:

Input

SELECT Media {
    hashtags,
    type := .__type__.name,
    [IS Text].title,
    [IS Text].body,
    [IS UploadedMedia].uri,
}
FILTER
    .author.<follows[IS User].email =
        'billie@tutorial.com'
ORDER BY .post_date DESC
LIMIT 5;

SELECT Media {
    hashtags,
    type := .__type__.name,
    [IS Text].title,
    [IS Text].body,
    [IS UploadedMedia].uri,
}
FILTER
    .author.<follows[IS User].email =
        'billie@tutorial.com'
ORDER BY .post_date DESC
LIMIT 5;

Run

Output

Press the 'Run' button to evaluate the input

Finally, all the data necessary to render a user's page with their feed can be packed into a single query:

Input

SELECT User {
    name,
    email,
    last_post := (
        SELECT .<author[IS Media] {
            hashtags,
            type := .__type__.name,
            [IS Text].title,
            [IS Text].body,
            [IS UploadedMedia].uri,
        }
        ORDER BY .post_date DESC
        LIMIT 1
    ),
    feed := (
        SELECT .follows.<author[IS Media] {
            author: {
                name,
                email,
            },
            hashtags,
            type := .__type__.name,
            [IS Text].title,
            [IS Text].body,
            [IS UploadedMedia].uri,
        }
        ORDER BY .post_date DESC
        LIMIT 5
    ),
}
FILTER .email = 'alice@tutorial.com';

SELECT User {
    name,
    email,
    last_post := (
        SELECT .<author[IS Media] {
            hashtags,
            type := .__type__.name,
            [IS Text].title,
            [IS Text].body,
            [IS UploadedMedia].uri,
        }
        ORDER BY .post_date DESC
        LIMIT 1
    ),
    feed := (
        SELECT .follows.<author[IS Media] {
            author: {
                name,
                email,
            },
            hashtags,
            type := .__type__.name,
            [IS Text].title,
            [IS Text].body,
            [IS UploadedMedia].uri,
        }
        ORDER BY .post_date DESC
        LIMIT 5
    ),
}
FILTER .email = 'alice@tutorial.com';

Run

Output

Press the 'Run' button to evaluate the input

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