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.
Tables and custom SQL query results can now be exported as CSV.
The easiest way to do this is to use the .csv extension, e.g.
/test_tables/facet_cities.csv
By default this is served as Content-Type: text/plain so you can see it in
your browser. If you want to download the file (using text/csv and with an
appropriate Content-Disposition: attachment header) you can do so like this:
/test_tables/facet_cities.csv?_dl=1
We link to the CSV and downloadable CSV URLs from the table and query pages.
The links use ?_size=max and so by default will return 1,000 rows.
Also fixes#303 - table names ending in .json or .csv are now detected and
URLs are generated that look like this instead:
/test_tables/table%2Fwith%2Fslashes.csv?_format=csv
The ?_format= option is available for everything else too, but we link to the
.csv / .json versions in most cases because they are aesthetically pleasing.
If the user requests some _facet= options that do not successfully execute in
the configured facet_time_limit_ms, we now show a warning message like this:
These facets timed out: rowid, Title
To build this I had to clean up our SQLite interrupted logic. We now raise a
custom InterruptedError exception when SQLite terminates due to exceeding a
time limit.
In implementing this I found and fixed a logic error where invalid SQL was
being generated in some cases for our faceting calculations but the resulting
sqlite3.OperationalError had been incorrectly captured and treated as a
timeout.
Refs #255Closes#269