DSN: support / in database name

[derekperkins]

Issue description

I use Vitess as a sharded MySQL instance. To connect to a specific shard of the database, the syntax expects dbname/shardname in the DSN, which looks something like this

mysql://username:password@host:1234/dbname/0?interpolateParams=true

I'm able to successfully use this style of DSN in other language drivers - specifically Python via mycli.

Someone brought up a similar issue in #1193 that was closed. I can see in the parsing code that it relies on finding the last slash
https://github.com/zihengCat/mysql/blob/18e71cd4a02b285470363e0f4ddbe58b549230a7/dsn.go#L295-L297

Would you be open to a PR that supported a slash in the db name?

Related issue:

• I want to use "/" in the name of DB. What should I do? #1193

[methane]

I'm open, but please don't assume I will merge it.
Please be clear about edge cases and backward compatibility.

[derekperkins]

Do you feel that the current test cases are sufficient to cover edge cases and backwards compatibility?

[methane]

I don't know.

[dolmen]

@derekperkins Have you tried filling a Config (use NewConfig) with your settings and call its FormatDSN method to see what it outputs? I expect that your case is already handled (I see a call to url.PathEscape in the code).

Here is a template: https://go.dev/play/p/8E3WFHsTTJc

[derekperkins]

@dolmen I'm not using this driver directly, I'm configuring the backing grafana database. That being said, I've been using the single url option, so maybe setting the individual fields will have a better outcome

https://grafana.com/docs/grafana/latest/setup-grafana/configure-grafana/#url

[dolmen]

@derekperkins mysql://username:password@host:1234/dbname/0?interpolateParams=true is not a valid DSN for the MySQL driver. Our DSN doesn't have that mysql:// prefix. It looks like Grafana has another DSN layer over it. You should start investigating there first.

[dolmen]

Our README says:

dbname is escaped by PathEscape() since v1.8.0. If your database name is dbname/withslash

... but v1.8.0 is not yet released.

This is commit d3e4fe6 from #1432.

So the issue is fixed, but not released yet.

[derekperkins]

Looks like Grafana does a url parse
https://github.com/grafana/grafana/blob/41e3b3bea2d91f9da38d65bfee89f321499ea3f9/pkg/services/sqlstore/sqlstore.go#L471-L491

Then fmt it into a go-sql-driver compatible DSN
https://github.com/grafana/grafana/blob/16d0aff26707b80fda408708d1c67bb2fe0586e9/pkg/services/sqlstore/sqlstore.go#L283-L317C33

I also checked with https://github.com/xo/usql, which uses https://github.com/xo/dburl to parse the agnostic string, and it returned the same error from go-sql-driver.

I can test it out directly to see if it works going straight through the driver

[derekperkins]

So the issue is fixed, but not released yet.

Oh, awesome - sorry for not seeing your comment before I posted. Thanks for tracking down that PR @dolmen and thanks @methane for the implementation!