Redesign JSON output, ditch jsono, offer variants controlled by parameter instead

[simonw]

I want to support three variants for the rows output:

• a list of lists, with a columns key saying what they are
• a list of dictionaries
• a single dictionary where the keys are the primary keys of the rows and the values are the row dictionaries themselves

I also want to make the various bits of metadata opt-in - so you don't get the SQL statement unless you ask for it.

These output options should be controlled by query string arguments.

I will set the .jsono URL to redirect to .json with the corresponding options.

[simonw]

For the overall shape of the rows:

?_shape=lists (default), ?_shape=objects, ?_shape=object (primary key as object keys)

For getting back extra keys:

?_extras=schema,query,timing

For expanding columns:

?_expand_all=1

Or ?_expand=qSpecies&_expand=qCaretaker

The template view will only be allowed to work with data it can request using extra options.

That leaves one sighted nasty edge-case: the default view will expand all columns, but the .json view of it won't?

I think that's OK. The default view won't include the extras used by the template to render the page either.

[simonw]

This calls for refactoring the code so the table view, the row view and the custom SQL view share as much logic as possible.

[simonw]

To start with, I could just ditch the .jsono in favour of the new _shape argument.

[simonw]

I think .json should continue to return rows as list-of-lists - it's a nice default because it produces a smaller overall JSON file. Encouraging people to specify an alternative shape to get the current .jsono format feels appropriate.

[simonw]

The new documentation for the _shape= parameter is now live at http://datasette.readthedocs.io/en/latest/json_api.html