issue_comments

But then what kind of magic parameters might plugins want to add?

Here's a crazy idea: _scrapedcontent_url - it would look for the url column on the data being inserted, scrape the content from it and insert that. This does suggest that the magic resolving function scrapedcontent() would need to optionally be sent the full row dictionary being inserted too.

Brainstorming more potential magic parameters:

• _actor_id
• _actor_name
• _request_ip
• _request_user_agent
• _cookie_cookiename
• _signedcookie_cookiename - reading signed cookies would be cool, not sure how to specify namespace though, maybe always use the same one? Or have the namespace come last, _signedcookie_cookiename_mynamespace. Might not need special signed cookie support since actor is already usually from a signed cookie.
• _timestamp_unix (not happy with these names yet)
• _timestamp_localtime
• _timestamp_datetime
• _timestamp_utc

I'd be OK with the first version of this not including a plugin hook.

If every magic parameter has a prefix and suffix, like _request_ip and _actor_id, then plugins could register a function for a prefix. Register a function to _actor and actor("id")will be called for _actor_id.

But does it make sense for every magic parameter to be of form _a_b? I think so.

The _actor_id param makes this a bit trickier, because we can't just say "if you see an unknown parameter called X call this function" - our magic parameter logic isn't adding single parameters, it might add a whole family of them.

Yes that can work - and using __missing__ (new in Python 3) is nicer because then the regular dictionary gets checked first: ```python import sqlite3

conn = sqlite3.connect(":memory:")

class Magic(dict): def missing(self, key): return key.upper()

conn.execute("select :name", Magic()).fetchall() Outputs: [('NAME',)] ```

It would be nice if Datasette didn't have to do any additional work to find e.g. _request_ip if that parameter turned out not to be used by the query.

Could I do this with a custom class that implements __getitem__() and then gets passed as SQLite arguments?