At the moment it's not easy to tell whether the hook is being called
in (for example) the row or table view, as in both cases the
`database` and `table` parameters are provided.
This passes the `view_name` added in #441 to the `extra_body_script`
hook.
This stops my automatic editor linting from flagging lines which are too
long. It's been lingering in my checkout for ages.
160 is an arbitrary large number - we could alter it if we have any
opinions (but I find the line length limit to be my least favourite part
of PEP8).
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
If an error occurred inside the block the progress handler (used to
enforce a time limit) was not being correctly cleared, resulting in
timeout errors potentially occurring during subsequent SQL queries.
The fix is described here: https://docs.python.org/3/library/contextlib.html#contextlib.contextmanager
