Datasette previously only supported one type of faceting: exact column value counting.
With this change, faceting logic is extracted out into one or more separate classes which can implement other patterns of faceting - this is discussed in #427, but potential upcoming facet types include facet-by-date, facet-by-JSON-array, facet-by-many-2-many and more.
A new plugin hook, register_facet_classes, can be used by plugins to add in additional facet classes.
Each class must implement two methods: suggest(), which scans columns in the table to decide if they might be worth suggesting for faceting, and facet_results(), which executes the facet operation and returns results ready to be displayed in the UI.
Also introduced a mechanism whereby table counts are calculated against a time limit
but immutable databases have their table counts calculated on server startup.
Thanks @russss!
* Add register_output_renderer hook
This changeset refactors out the JSON renderer and then adds a hook and
dispatcher system to allow custom output renderers to be registered.
The CSV output renderer is untouched because supporting streaming
renderers through this system would be significantly more complex, and
probably not worthwhile.
We can't simply allow hooks to be called at request time because we need
a list of supported file extensions when the request is being routed in
order to resolve ambiguous database/table names. So, renderers need to
be registered at startup.
I've tried to make this API independent of Sanic's request/response
objects so that this can remain stable during the switch to ASGI. I'm
using dictionaries to keep it simple and to make adding additional
options in the future easy.
Fixes#440
Prior to this commit Datasette would calculate the content hash of every
database and redirect to a URL containing that hash, like so:
https://v0-27.datasette.io/fixtures => https://v0-27.datasette.io/fixtures-dd88475
This assumed that all databases were opened in immutable mode and were not
expected to change.
This will be changing as a result of #419 - so this commit takes the first step
in implementing that change by changing this default behaviour. Datasette will
now only redirect hash-free URLs under two circumstances:
* The new `hash_urls` config option is set to true (it defaults to false).
* The user passes `?_hash=1` in the URL
If you start Datasette with no files, it will connect to :memory: instead.
When starting it with files you can add --memory to also get a :memory: database.
Means `datasette publish heroku` can work under Travis, unlike this failure:
https://travis-ci.org/simonw/fivethirtyeight-datasette/builds/488047550
```
2.25s$ datasette publish heroku fivethirtyeight.db -m metadata.json -n fivethirtyeight-datasette
tar: unrecognized option '--exclude-vcs-ignores'
Try 'tar --help' or 'tar --usage' for more information.
▸ Command failed: tar cz -C /tmp/tmpuaxm7i8f --exclude-vcs-ignores --exclude
▸ .git --exclude .gitmodules . >
▸ /tmp/f49440e0-1bf3-4d3f-9eb0-fbc2967d1fd4.tar.gz
▸ tar: unrecognized option '--exclude-vcs-ignores'
▸ Try 'tar --help' or 'tar --usage' for more information.
▸
The command "datasette publish heroku fivethirtyeight.db -m metadata.json -n fivethirtyeight-datasette" exited with 0.
```
The fix for that issue is to call the heroku command like this:
heroku builds:create -a app_name --include-vcs-ignore
The extra_css_urls and extra_js_urls hooks now take additional optional
parameters.
Also refactored them out of the Datasette class and into RenderMixin.
Plus improved plugin documentation to explicitly list parameters.