How to not marshal an empty struct into JSON with Go?

by

As the docs say, “any nil pointer.” — make the struct a pointer. Pointers have obvious “empty” values: nil.

Fix – define the type with a struct pointer field:

type Result struct {
    Data       *MyStruct `json:"data,omitempty"`
    Status     string    `json:"status,omitempty"`
    Reason     string    `json:"reason,omitempty"`
}

Then a value like this:

result := Result{}

Will marshal as:

{}

Explanation: Notice the *MyStruct in our type definition. JSON serialization doesn’t care whether it is a pointer or not — that’s a runtime detail. So making struct fields into pointers only has implications for compiling and runtime).

Just note that if you do change the field type from MyStruct to *MyStruct, you will need pointers to struct values to populate it, like so:

Data: &MyStruct{ /* values */ }

More Related Contents:

  1. How I can encode JSON with multiple elements in Go Lang [closed]
  2. Go JSON Naming strategy about extends
  3. json.Marshal(struct) returns “{}”
  4. JSON and dealing with unexported fields
  5. How to parse/deserialize dynamic JSON
  6. My structures are not marshalling into json [duplicate]
  7. Unmarshal JSON with some known, and some unknown field names
  8. Converting Go struct to JSON
  9. json.Unmarshal returning blank structure
  10. Decoding generic JSON objects to one of many formats
  11. (un)marshalling json golang not working
  12. Taking a JSON string, unmarshaling it into a map[string]interface{}, editing, and marshaling it into a []byte seems more complicated then it should be
  13. Printing Empty Json as a result [duplicate]
  14. Lowercase JSON key names with JSON Marshal in Go
  15. Why struct fields are showing empty?
  16. Unmarshaling nested JSON objects
  17. Unmarshaling json in Go: required field?
  18. How to marshal a byte/uint8 array as json array in Go?
  19. How do I send a JSON string in a POST request in Go
  20. Partly JSON unmarshal into a map in Go
  21. Parsing multiple JSON objects in Go
  22. Is it possible to partially decode and update JSON? (go)
  23. How to parse JSON in golang without unmarshaling twice
  24. Decode JSON as it is still streaming in via net/http
  25. json unmarshal time that isn’t in RFC 3339 format
  26. How to unmarshal JSON into interface{} in Go?
  27. Call json.Unmarshal inside UnmarshalJSON function without causing stack overflow
  28. JSON single value parsing
  29. unmarshalling arbitrary data
  30. How to format timestamp in outgoing JSON

Leave a Comment