golang可有效处理Null *类型

Question

If one is working with a database, a Null* type is useful for most scenarios as one typically does not want a "zero" value going through, you want the NOT NULL constraints etc. to kick up and remind you that you haven't passed in all the data necessary.

So you create a structure like the following:

type Role struct {
    Id   sql.NullInt64
    Code sql.NullString
}

Thats great, but now you cannot get direct access to the properties and have to use Role.Id.Value to both get and set, this is going to get pretty old in a large app when you have to have the extra step every single time you want access to the properties.

It would be nice if you could assign directly eg. Role.Code = "Fsfs", and be able to do something like Role.Code.IsNull when you are interested in null checking. Is such a thing possible?

Answer 1

Is using intermediate pointer value(s) an option?

package main

import "fmt"

type tmp struct {
    Value int
}

func getInt() *int {
    i := 123

    return &i
}

func main() {
    // Re
    var v *int

    v = nil

    fmt.Printf("%T / %v
", v, v)

    if v == nil {
        println("nil...")
    }

    v = getInt()

    fmt.Printf("%T / %v
", v, *v)

    if v != nil {
        println("not nil...")
    }

    s := tmp{*v}

    fmt.Printf("%T / %v
", s, s)
}

http://play.golang.org/p/lBrwTKh6-v