Add support for date/time to SQLite

[sgrif]

Currently SQLite has no support for any of the date/time types. Let's add support back for these, as well as SystemTime. We should probably have an intermediate struct which others can reason about, similar to how we handled PgDate and friends.

[aperezdc]

There's an attempt to implement this in PR #344 — which is a bit old and seems to need some love.

[euclio]

Any way I can help get this moving? What still needs to be done?

[kballard]

Same here. I'd love to see this get done, and I'm happy to help if someone wants to provide some direction.

[killercup]

@euclio @kballard sorry, I wasn't watching this issue. We would definitely appreciate your help! I'm not sure I can really follow it, but I think the main issue with #344 is that we need to make sure that SQLite gives us date/times in a format we can definitely parse.

Maybe you can drop by our Gitter room and we see how we can tackle this?

[Eijebong]

Oh, I missed this one :o

Can this be closed now or is SQLite still missing something regarding date/time ? (see #887)

[sgrif]

Yeah, I think so. I had envisioned broader support than #887 added, but I don't see any way to do that since we have to do string parsing with these types.

[gentoo90]

Are there any plans to add schema inference for DATE, TIME, DATETIME and TIMESTAMP?
Currently (master, 560f650) they all fail:

diesel/diesel_cli $ sqlite3 test_datetime.db 'CREATE TABLE test (id INTEGER PRIMARY KEY, dt DATETIME)'
diesel/diesel_cli $ echo 'DATABASE_URL=test_datetime.db' > .env
diesel/diesel_cli $ RUST_BACKTRACE=1 cargo run print-schema
    Finished release [optimized] target(s) in 0.0 secs
     Running `/home/igor/projects/rust/diesel/target/release/diesel print-schema`
thread 'main' panicked at 'Could not load table `test`: StringError("Error determining type of test.dt: Unsupported type: datetime")', /checkout/src/libcore/result.rs:859

[sgrif]

/cc @Eijebong

[Eijebong]

Yeah, it makes sense. Fixing it

Edit: after lunch

[Eijebong]

This is now fixed. @gentoo90, thanks for the report :)

[gentoo90]

Thanks for the fix!