wucke13
43 lines
2.0 KiB
SQL
43 lines
2.0 KiB
SQL
SELECT 'list' AS component,
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'Navigation' AS title;
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SELECT
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column1 AS title, column2 AS link, column3 AS description_md
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FROM (VALUES
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('Link to arbitrary path', '/api/does/not/actually/exist', 'Covered by `api/404.sql`'),
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('Link to arbitrary file', '/api/nothing.png', 'Covered by `api/404.sql`'),
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('Link to non-existing .sql file', '/api/inexistent.sql', 'Covered by `api/404.sql`'),
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('Link to 404 handler', '/api/404.sql', 'Actually `api/404.sql`'),
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('Link to API landing page', '/api', 'Covered by `api/index.sql`'),
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('Link to arbitrary broken path', '/backend/does/not/actually/exist', 'Not covered by anything, will yield a 404 error')
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);
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SELECT 'text' AS component,
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'
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# Overview
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This demo shows how a `404.sql` file can serve as a fallback error handler. Whenever a `404 Not
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Found` error would be emitted, instead a dedicated `404.sql` is called (if it exists) to serve the
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request. This is usefull in two scenarios:
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1. Providing custom 404 error pages.
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2. To provide content under dynamic paths.
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The former use-case is primarily of cosmetic nature, it allows for more informative, customized
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failure modes, enabling better UX. The latter use-case opens the door especially for REST API
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design, where dynamic paths are often used to convey arguments, i.e. `/api/resource/5` where `5` is
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the id of a resource.
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# Fallback Handler Selection
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When a normal request to either a `.sql` or a static file fails with `404`, the `404` error is
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intercepted. The reuquest path''s target directory is scanned for a `404.sql`. If it exists, it is
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called. Otherwise, the parent directory is scanned for `404.sql`, which will be called if it exists.
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This search traverses up until it reaches the `web_root`. If even the webroot does not contain a
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`404.sql`, then the original `404` error is served as response to the HTTP client.
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The fallback handler is not recursive; i.e. if anything causes another `404` during the call to a
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`404.sql`, then the request fails (emitting a `404` response to the HTTP client).
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' AS contents_md;
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