Provide a implementation of diesel::connection::Connection for the connection type in this crate

[weiznich]

As part of the diesel 2.0 release we reworked large parts of diesels internals, such that it should now be possible to provide a custom Connection implementation for the existing diesel mysql backend outside of the main crate. Your crate would be a good candidate for this as it already provides a pure rust mysql connection implementation. I expect that there would be a certain demand in having a pure rust connection implementation supported by diesel as well.

A diesel connection implementation would enable the usage of any supported diesel feature with a connection type from your crate. This includes all of the existing query DSL, all methods to load and map results to rust struct and even the existing migration infrastructure.

This would require implementing diesel::connection::Connection either directly for your connection type or indirectly via a wrapper type. Providing this implementation as part of your crate would enable a better integration with optimizations like prepared statement caching.

If you are interested in such feature I'm happy to provide guidance on writing the corresponding code. I might even be able to help writing parts of the implementation.

[blackbeam]

Hi. This sounds great.
I'll work on this as soon as my vacation is over (since May).

[somehowchris]

Just started out, @weiznich is there a way to split the mysql backend and mysql connection parts of diesel via features? Currently the mysql feature automatically enables the mysqlclient-sys feature

[somehowchris]

nvm, sry saw that upstream there is a mysql_backend feature, but as 2.0 isn't yet released, cargo add didn't show me these features

[weiznich]

Yes such an implementation should depend on diesel 2.0 and use the mysql_backend feature. You can use the 2.0.0-rc.1 for the initial development. Hopefully we are able to release a final 2.0 version this month. There are no large breaking changes planed that could affect a third party connection implementation.

[somehowchris]

Is there anything against deriving Debug for diesel::connection::AnsiTransactionManager?

[weiznich]

Not really. Adding such a derive should be fine. It's likly just an oversight that it is not already there. I will open a PR for this later today.
For now you can use TransactionManager::transaction_manager_status_mut to get access to the only inner field. That type returned there already implements Debug.