Type has no field or method

Question

I have a problem with a struct's method. In one file (same package) I a struct:

type Task struct {
    ID       int    `json:"id"`
    Priority string `json:"priority"`
    Content  string `json:"content"`
}

The Task comes as a body in POST. Parsing the JSON to this struct works well. In other file I have a method:

func (task *Task) createTask() (err error) {
    data, err := bson.Marshal(&task)
    if err != nil {
        return errors.New("error in parsing incoming task")
    }
    rslt, err := collection.InsertOne(context.Background(), data)
    if err != nil {
        return errors.New("error in saving task to database")
    }
    fmt.Println(rslt.InsertedID)
    return nil
}

The Task structure is in the same file with my server. createTask() method is in the file which handles communication to mongoDB. When I run my server I have this error:

./server.go:53:12: task.createTask undefined (type Task has no field or method createTask)

Here is how I am calling the method:

var task Task
json.Unmarshal(body, &task)
err = task.createTask()

Do you have any ideas what am I doing wrong?

Answer 1

This got me as well >.<

Go only considers functions that begin with a capital letter to be exported; including member functions. So you need to change:

func (task *Task) createTask() (err error) {
   ...

to

func (task *Task) CreateTask() (err error) {
   ...

and similarly at the call site.

Go's error unfortunately doesn't tell you how to fix this if you wrote the module and intend for the function to be exported.