Golang代码结构

Question

Is it worth to group methods in structs: For example:

type UserManager struct {
    DB *sql.DB
}

func (m UserManager) Insert (u User) error {...}
func (m UserManager) Delete (u User) error {...}
...

Or is it simpler support just separate functions.

func InsertUser (u User, db *sql.DB) error {...}

While second approach looks simpler at first, in future this way, there may be to many functions in package. Should I make separate package for every domain aggregate? In examples, I've seen so far, there is just model package. I've been working mainly with OO languages so need some advice for go best practices here.

Answer 1

Your second suggestion is not good go code! Why? Because in the best case a function should take interfaces as an input.

So a InsertUserfunction should look something like that and it would combine your first with your second suggestion:

type Inserter interface {
   Insert(User)error
}
func InsertUser(i Inserter) error {...}

In that case testing of your function is easy, because you can easy mock the inserter.