CODEWITHSUNDEEP
gonullreflect
Zouglou
Zouglou

Reputation: 129

How to check reflect.Value is nil or not?

I have this code:

package main

import (
    "fmt"
    "reflect"
)


type cmd struct{
    Echo func(string) (string,error)
}



func main() {
    cmd := cmd{
        Echo : func(arg string) (string, error) {
            return arg, nil
        },
    }
    result := reflect.ValueOf(cmd).FieldByName("Echo").Call([]reflect.Value{reflect.ValueOf("test")})
    if result[1] == nil{
        fmt.Println("ok")
    }
}

I want to check if my error is nil, but in my code, it doesn't work cuz it has different types. I try to make like this :

reflect[1] == reflect.Value(reflect.ValueOf(nil))

So it has the same type but the value of reflect.Value(reflect.ValueOf(nil)) isn't nil, it is <invalid reflect.Value>.

Upvotes: 4

Views: 10899

Answers (1)

Eklavya
Eklavya

Reputation: 18480

Use .IsNil() to check whether the value that's stored in reflect.Value is nil.

if result[1].IsNil() {
   fmt.Println("ok")
}

Or you can use .Interface() to get the actual value that's stored in reflect.Value and check whether this is nil.

if result[1].Interface() == nil {
    fmt.Println("ok")
}

Upvotes: 10

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