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