Using Go's reflect package, is there a way to set a pointer in a struct if the pointer is nil? Looking at the reflect package, if reflect.Value.CanSet()
is false
then any Set()
calls will yield a panic. Is there another way around this, only using the reflect package, not depending on any direct reference to the struct? For example, how can I set the empty last name as "Johnson" in the code below?
package main
import (
"fmt"
"reflect"
)
type Person struct {
FirstName *string
LastName *string
}
func main() {
p := Person{}
firstName := "Ryan"
p.FirstName = &firstName
rp := reflect.ValueOf(p)
fmt.Println("rp:", rp)
for i := 0; i < rp.NumField(); i++ {
fmt.Printf("%s: Pointer: %d CanSet: %t\n", rp.Type().Field(i).Name, rp.Field(i).Pointer(), rp.Field(i).Elem().CanSet())
}
rp.Field(0).Elem().SetString("Brian")
fmt.Println(*p.FirstName)
// Yields nil pointer error
// rp.Field(1).Elem().SetString("Johnson")
// fmt.Println(*p.LastName)
fmt.Println(rp.Field(1).Type())
fmt.Println(rp.Field(1).CanSet())
// fmt.Println(rp.Field(1).Elem().Type()) // nil pointer here also
fmt.Println(rp.Field(1).Elem().CanSet())
}
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