ID() (string, time.Time) cannot match to entity without rounding

[tvanriper]

Take a structure like this:

type Session struct {
	Start        time.Time   `json:"start"`
	End          time.Time   `json:"end"`
	Client       string      `json:"client"`
}

and try to devise an 'ID' that refers to "start", say with:

// ID provides a unique identifier for this session
func (s Session) ID() (string, interface{}) {
	return "start", s.Start.UnixNano()
}

The records never match.

• time.Time doesn't honor '==', requiring time.Time.Equal(time.Time) to denote equality, so ID() can't return s.Start per the example.
• s.Start.UnixNano() doesn't seem to match, perhaps because there's some randomness.
• s.Start.Unix() works, but requires something like Session.Start = time.Now().Round(time.Second) to work.
• s.Start.Format(time.RFC3339) also works, but requires Session.Start = time.Now().Round(time.Second)