转到使用db.Query返回多个列

Question

In the Go SQL docs they give an example here of a query that only returns 1 column (poor example in my opinion, at least return 2...)

age := 27
rows, err := db.Query("SELECT name FROM users WHERE age=?", age)
if err != nil {
        log.Fatal(err)
}
for rows.Next() {
        var name string
        if err := rows.Scan(&name); err != nil {
                log.Fatal(err)
        }
        fmt.Printf("%s is %d
", name, age)
}
if err := rows.Err(); err != nil {
        log.Fatal(err)
}

The docs state here that Scan copies the columns in the current row into the values pointed at by dest.

How does this work with a struct, lets say I have a struct

type User struct{
    Name string
    Age int
}

and I modify my query to SELECT name, age from users where age=?

How do I unpack *Rows into my struct? I did find this example, but it didn't deal with structs. I will be following Active Record pattern conventions so my structs will map to my database via snake case conversion.

Answer 1

Looking at the source, it seems the copy is done with ... syntax on destination pointers:

func (rs *Rows) Scan(dest ...interface{}) error

So in your example, you can do for instance:

for rows.Next() {
    u := User{} // An empty user
    ...
    if err := rows.Scan(&u.Name, &u.Age); err != nil {
        ...
    }
 }

As long as you pass the exact number of pointers, this should work, whether they are from a struct or not.