将数据库列扫描到带有切片的结构中

Question

I have a struct with fields containing slices like so, and now I want to collect the columns from a sql-query into these slices

type StructOfSlices struct {
    Column1 []string
    Column2 []string
}

Is there an easier/more scalable/efficient way to do it than the below?

Here I first create a "single" version of the struct...

type StructSingle struct {
    Column1 string
    Column2 string
}

var s StructOfSlices

rows, _ := db.Query("SELECT column1, column2 FROM table")

...and then scan each individual single struct...

for rows.Next() {
    var single StructSingle

    db.Scan(&single.Column1, &single.Column2)

    s.Column1 = append(s.Column1, single.Column1)
    s.Column2 = append(s.Column2, single.Column2)
}

...and then append to the slice struct

Answer 1

No, that's the way to do it. You're basically doing a pivot, there's no way I know of to do that automagically. Given that you've done it in just a couple of lines of code, I don't see a problem with your solution.

Since you're scanning into a variable per column, you don't actually need the StructSingle type at all - you could just use two local string variables, which would make it even simpler:

for rows.Next() {
    var col1, col2 string
    db.Scan(&col1, &col2)

    s.Column1 = append(s.Column1, col1)
    s.Column2 = append(s.Column2, col2)
}

And get rid of the StructSingle type entirely.