Scan into struct for db.QueryRow

[matrixik]

Hello,
Thank you for really useful package.

Maybe you can consider adding function to scan only one row into struct (for db.QueryRow).

Cheers

[kisielk]

I'm glad you find the package useful. Unfortunately I don't think we can support sql.QueryRow because the sql.Row type doesn't have a Columns() method which we need to decide which struct members to scan the result in to. If you have any suggestions for a possible implementation I'd be glad to hear them.

[matrixik]

Hmm, https://github.com/jmoiron/sqlx have something like that:

// You can also get a single result, a la QueryRow
jason = Person{}
err = db.Get(&jason, "SELECT * FROM person WHERE first_name=$1", "Jason")
fmt.Printf("%#v\n", jason)
// Person{FirstName:"Jason", LastName:"Moiron", Email:"jmoiron@jmoiron.net"}

But I don't have time now to investigate how it works and personally I think sqlx is a little overkill.

[kisielk]

db.Get in sqlx actually uses sql.Query under the hood, not sql.QueryRow, so it has access to Columns() to do the scanning. But yeah, sqlx is a more full-featured complete wrapper around database/sql whereas this package is just a few convenience functions that work with the existing API.

[matrixik]

Maybe something like this:
https://github.com/matrixik/sqlstruct/commit/f5a8e2e385f6304fdf194eacf0906ecccc9499ec

But I don't know if I can copy some of Go database/sql source here:
http://golang.org/src/database/sql/sql.go?s=44347:44803#L1703

[kisielk]

Yeah that works, but that's wrapping query which isn't what I want to do in this library. It doesn't really work analogous to how the Scan function works.

[matrixik]

So, any suggestions how to change it or you don't want something like that in you package?

[matrixik]

that's wrapping query which isn't what I want to do in this library

That's exactly what QueryRow is doing:
http://golang.org/src/database/sql/sql.go#L1001

[kisielk]

I don't want to wrap any sort of DB object and run queries within this package, that's not the intent of the design. At that point sqlx or similar would be better choice. The only way I could see it working is if we could get columns from a sql.Row object, so if the Go developers could be convinced to add a Columns() method to it like sql.Rows has. The chances of that happening are pretty slim I think.

[kisielk]

To put it another way, the package is built to function around anything that implements sqlstruct.Rows, which sql.Row does not. If it did, then it would work :)

[matrixik]

Would that be sufficient: golang/go#5606 ?
Or should I create new issue?

[kisielk]

That wouldn't help here, that issue is for an API for database driver authors. You would need to file a new issue for adding the Columns() method to sql.Row. To be honest I think it's probably not worth the effort, you could just use a simple utility function in your code base, basically what you had here: #5 (comment)

[matrixik]

Thank you for your time.