Empty default string does not work with string pointer type.

[fuhrmannb]

In this kind of structure:

type A struct {
	StrPtr *string `default:""`
}

A.StrPtr is not set to a pointer of String("") but is still nil.

Example of program highlighting this bug

package main

import (
	"fmt"

	"github.com/creasty/defaults"
)

type A struct {
	StrPtr *string `default:""`
}

func main() {
	var data A
	err := defaults.Set(&data)
	if err != nil {
		panic(err)
	}

	fmt.Println(data.StrPtr)
}

My guess is it's related to https://github.com/creasty/defaults/blob/master/defaults.go#L238 that does not change the field if the tag is empty, or an empty tag could be an empty string here.

I'm wondering if just returning true at the end of the shouldInitializeField method can work or it may break other cases?

[creasty]

We'd like to utilize Lookup() here to exclude fields without a tag, and then change shouldInitializeField to return true at the end.

defaults/defaults.go

Line 36 in abebf4b

if defaultVal := t.Field(i).Tag.Get(fieldName); defaultVal != "-" {