Pass sql.DB object instead of URL

[gosom]

Hello,

@amacneil and other contributors I would like to thank you for the good job.

I was looking for a way instead passing a database URL to pass an *sql.DB connection.

This does not look possible from my quick research.

I would like also to point out the following:

there is a driver interface

but when you look at the implementation of postgres

I understood that you try to connect to a default database or something .

On top of that Open is used for every command (see Ping also for example).

What is the reason for this behavior?

Wouldn't be more intuitive to create a database connection and perfom the operatios with this connection ?
This probably would allow to pass an *sql.DB already connected, which would be useful when you want to use dbmate as a library

[dossy]

Most of dbmate's functions expects a *sql.DB to act on. The only ones that don't are currently DatabaseExists(), CreateDatabase(), DropDatabase() and Ping().

It could be possible to optionally accept a *sql.DB parameter to those functions, in a backwards-compatible way, but as you point out, some drivers such as postgres need to open a separate connection when creating a database that doesn't exist, as you cannot connect to a database that doesn't exist yet, so we connect to the system postgres database to ensure we can connect, in order to create the database we need to create.

I suppose if you're invoking CreateDatabase() and are using dbmate as a library and want to pass an already-connected *sql.DB, then that means at that time the database already exists (otherwise you wouldn't be able to connect to it and wouldn't have a valid *sql.DB to pass in), and calling CreateDatabase() will be a no-op anyway, so why would you even need to invoke it?