Quick way to detect empty values via reflection in Go

Question

I have a int/string/bool/etc.. value stored in an interface{} and want to determine if it's uninitialized, meaning that it has a value of either

• 0
• ""
• false
• or nil

How do I check this?

Answer 1

From what I understand, you want something like:

func IsZeroOfUnderlyingType(x interface{}) bool {     return x == reflect.Zero(reflect.TypeOf(x)).Interface() } 

When talking about interfaces and nil, people always get confused with two very different and unrelated things:

1. A nil interface value, which is an interface value that doesn't have an underlying value. This is the zero value of an interface type.
2. A non-nil interface value (i.e. it has an underlying value), but its underlying value is the zero value of its underlying type. e.g. the underlying value is a nil map, nil pointer, or 0 number, etc.

It is my understanding that you are asking about the second thing.

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Update: Due to the above code using ==, it won't work for types that are not comparable. I believe that using reflect.DeepEqual() instead will make it work for all types:

func IsZeroOfUnderlyingType(x interface{}) bool {     return reflect.DeepEqual(x, reflect.Zero(reflect.TypeOf(x)).Interface()) }