I can't understand the logic of json.Marshal. Why is the output an empty object?

Question

go

Tell me please. There is this code:

type Test struct {
  text string `json:"test"`
}

var test Test
  test.text = "test message"

  result, err := json.Marshal(test)

  log.Println(test)
  log.Println(result)
  log.Println(err)

Screen

why result = {} and not {"test message"}

Screen

Answer 1

Here the point is that the `text` field is written with a small letter, which means it is not exportable.
That is why this is the result. And when you write it with a capital letter, everything will work as you expect.

Answer 2

As the doc says - https://blog.golang.org/json-and-go

only data structures that can be represented as valid JSON will be encoded:
JSON objects only support strings as keys; to encode a Go map type it must be of the form map[string]T (where T is any Go type supported by the json package).
Channel, complex, and function types cannot be encoded.
Cyclic data structures are not supported; they will cause Marshal to go into an infinite loop.
Pointers will be encoded as the values ​​they point to (or 'null' if the pointer is nil).
The json package only accesses the exported fields of struct types (those that begin with an uppercase letter). Therefore, only the exported fields of a struct will be present in the JSON output.