Looking for go Answers? Try Ask4KnowledgeBase
Looking for go Keywords? Try Ask4Keywords

Go Returning an error


In Go you don't raise an error. Instead, you return an error in case of failure.

// This method can fail
func DoSomething() error {
    // functionThatReportsOK is a side-effecting function that reports its
    // state as a boolean. NOTE: this is not a good practice, so this example
    // turns the boolean value into an error. Normally, you'd rewrite this
    // function if it is under your control.
    if ok := functionThatReportsOK(); !ok {
        return errors.New("functionThatReportsSuccess returned a non-ok state")

    // The method succeeded. You still have to return an error
    // to properly obey to the method signature.
    // But in this case you return a nil error.
    return nil

If the method returns multiple values (and the execution can fail), then the standard convention is to return the error as the last argument.

// This method can fail and, when it succeeds,
// it returns a string.
func DoAndReturnSomething() (string, error) {
    if os.Getenv("ERROR") == "1" {
        return "", errors.New("The method failed")

    s := "Success!"

    // The method succeeded.
    return s, nil

result, err := DoAndReturnSomething()
if err != nil {