How Can I Detect Empty Values (Including Nil) in Go Using Reflection?

Detecting Empty Values with Reflection in Go

In Go, when dealing with an interface{} that holds a value of various types such as int, string, bool, or nil, it may be useful to determine if the value is uninitialized. This often corresponds to zero values such as 0 for integers, "" for strings, false for booleans, and nil for pointers.

Intuitive Solution

One approach to this problem is to utilize reflection to inspect the value's type and compare it to the corresponding zero value for that type:

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

Handling Nil Values

It is important to distinguish between a nil interface value and an interface value with an underlying zero value. A nil interface value has no underlying value, while an interface value with an underlying zero value has a value that matches the zero value for its underlying type.

Update for Non-comparable Types

The original solution utilized equality (==) comparison, which may not work for all types. For instance, some structs or types may not implement the equality operator. To ensure compatibility with all types, the DeepEqual function from the reflect package can be used instead:

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

With this update, the code should accurately detect empty values for any type, regardless of its comparability.

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