How to recognize void value and unspecified field when unmarshaling in Go?

Question

I would like to know if it\'s possible to differenciate a void value and an unspecified field value.

Here is an example:

var jsonBlob = []byte(`[
           


        

Answer 1

You can distinguish between empty and missing values if you change your field type to be a pointer. If the value is present in JSON with an empty string value, it will be set to a pointer that points to an empty string. If it is not present in JSON, it will be left nil.

type Category struct {
    Name        string
    Description *string
}

Output (try it on the Go Playground):

[{Name:A Description:0x1050c150} {Name:B Description:<nil>} {Name:C Description:0x1050c158}]