datasette 1.0a8 on Python PyPI

This alpha release continues the migration of Datasette's configuration from metadata.yaml to the new datasette.yaml configuration file, introduces a new system for JavaScript plugins and adds several new plugin hooks.

See Datasette 1.0a8: JavaScript plugins, new plugin hooks and plugin configuration in datasette.yaml for an annotated version of these release notes.

Configuration

Plugin configuration now lives in the datasette.yaml configuration file, passed to Datasette using the -c/--config option. Thanks, Alex Garcia. (#2093)
```
datasette  -c  datasette.yaml
```
Where datasette.yaml contains configuration that looks like this:
```
plugins:
  datasette-cluster-map:
    latitude_column: xlat
    longitude_column: xlon
```
Previously plugins were configured in metadata.yaml, which was confusing as plugin settings were unrelated to database and table metadata.
The -s/--setting option can now be used to set plugin configuration as well. See Configuration via the command-line for details. (#2252)
The above YAML configuration example using -s/--setting looks like this:
```
datasette  mydatabase.db\
  -s  plugins.datasette-cluster-map.latitude_column  xlat\
  -s  plugins.datasette-cluster-map.longitude_column  xlon
```
The new /-/config page shows the current instance configuration, after redacting keys that could contain sensitive data such as API keys or passwords. (#2254)
Existing Datasette installations may already have configuration set in metadata.yaml that should be migrated to datasette.yaml. To avoid breaking these installations, Datasette will silently treat table configuration, plugin configuration and allow blocks in metadata as if they had been specified in configuration instead. (#2247) (#2248) (#2249)

Note that the datasette publish command has not yet been updated to accept a datasette.yaml configuration file. This will be addressed in #2195 but for the moment you can include those settings in metadata.yaml instead.

JavaScript plugins

Datasette now includes a JavaScript plugins mechanism, allowing JavaScript to customize Datasette in a way that can collaborate with other plugins.

This provides two initial hooks, with more to come in the future:

makeAboveTablePanelConfigs() can add additional panels to the top of the table page.
makeColumnActions() can add additional actions to the column menu.

Thanks Cameron Yick for contributing this feature. (#2052)

Plugin hooks

New jinja2_environment_from_request(datasette, request, env) plugin hook, which can be used to customize the current Jinja environment based on the incoming request. This can be used to modify the template lookup path based on the incoming request hostname, among other things. (#2225)
New family of template slot plugin hooks: top_homepage, top_database, top_table, top_row, top_query, top_canned_query. Plugins can use these to provide additional HTML to be injected at the top of the corresponding pages. (#1191)
New track_event() mechanism for plugins to emit and receive events when certain events occur within Datasette. (#2240)
- Plugins can register additional event classes using register_events(datasette).
- They can then trigger those events with the datasette.track_event(event) internal method.
- Plugins can subscribe to notifications of events using the track_event(datasette, event) plugin hook.
- Datasette core now emits login, logout, create-token, create-table, drop-table, insert-rows, upsert-rows, update-row, delete-row events, documented here.
New internal function for plugin authors: await db.execute_isolated_fn(fn), for creating a new SQLite connection, executing code and then closing that connection, all while preventing other code from writing to that particular database. This connection will not have the prepare_connection() plugin hook executed against it, allowing plugins to perform actions that might otherwise be blocked by existing connection configuration. (#2218)

Documentation

Documentation describing how to write tests that use signed actor cookies using datasette.client.actor_cookie(). (#1830)
Documentation on how to register a plugin for the duration of a test. (#2234)
The configuration documentation now shows examples of both YAML and JSON for each setting.

Minor fixes

Datasette no longer attempts to run SQL queries in parallel when rendering a table page, as this was leading to some rare crashing bugs. (#2189)
Fixed warning: DeprecationWarning: pkg_resources is deprecated as an API (#2057)
Fixed bug where ?_extra=columns parameter returned an incorrectly shaped response. (#2230)