从PostGres DB获取结构

Question

I followed a thread in here and came up with this

var b Button

queryErr := connection.QueryRow("SELECT id_printer, name, has_children FROM button WHERE id_parent IS NULL;").Scan(&b.ID, &b.Name, &b.Children)
if queryErr != nil {
    response, err := json.MarshalIndent(b, "", "  ")
    fmt.Fprint(w, string(response))
    if err != nil {
        log.Println("Error on jsonmarshalindent Starter")
    }
} else {
    log.Println("Error on queryErr  starter")
    log.Println(queryErr)

    fmt.Fprint(w, "Error getting starter button")
}

it has 2 problems:

1. It breaks on b.Children
2. I don't know how to make it dynamically. for instance, the query returns 3 rows, but it depends on the company's client, it can be 3 or any number.

the struct is

type Starter struct {
    Buttons []Button `json:buttons`
}

type Button struct {
    ID       int    `json:id`
    Name     string `json:name`
    Children bool   `json:children`
}

Can someone shed some light in this please?

Answer 1

For the bool, it depends on the type of the actual column. If it isn't boolean, it won't map directly.

You may need to store in a temporary variable first and then translate and assign to the field in Button to match.

As for reading all rows, here's an example adapted from the docs.

You use Query instead of QueryRow to get all rows.

rows, err := db.Query("SELECT id_printer, name, has_children FROM button WHERE id_parent IS NULL;")
if err != nil {
        log.Fatal(err)
}
defer rows.Close()
var buttons []Button
for rows.Next() {
        var b Button
        if err := rows.Scan(&b.ID, &b.Name, &b.Children); err != nil {
                log.Fatal(err)
        }
        buttons = append(buttons,b)
}
// At this point, you have all your rows in the "buttons" variable