This tool generates sql.Scanner and sql.Valuer interfaces for your own structs and type aliases. It is tested with Postgres and lib/pq library, others might work. The command is quite self explanatory, use the --help option to understand the parameters.
The example folder provides you with tests and structs to understand how this tool works. Run go generate in the example folder to generate the interfaces. Then you can run go test to see if all works. It tries to connect to a local postgres instance and needs a database named custom.
The -array param generates array types as well, the -sql param adds a Init function that can be used to create the composite type in postgres.
There is support for type aliases. To generate scanner and valuer for type aliases you can pass them through the alias param.