Error handling is very important in software development.
1. A missing value is an error
Assume we have UserRepo and want to define a method to get User by id .
1) C++/Java style
func (s *UserRepo) Get(ctx context.Context, id int64) (*User)2) Go Style
func (s *UserRepo) Get(ctx context.Context, id int64) (u *User, err error)Someone prefers to use err as DB query error, u = nil to represent user not found, which would bring troubles to the caller.
u, err := userRepo.Get(ctx, id)
if err != nil {
return err
}if u != nil {
return errors.New("user not found")
}...
Actually, we should use err to represent user not found , e.g. declare an error ErrNotExist . If err is not nil, u is nil or invalid value. Thus, the caller only needs to check one value instead of two.
u, err := userRepo.Get(ctx, id)
if err != nil {
return err
}...
2. Never ignore any error
Rember to check every error. Usually, we have two options:
1) Handle error appropriately
2) Return error if you don’t know how to handle
Avoid using panic , most errors can be handled or recoverable.
