Say I have a UserModel like so:
type (
OrderModel struct {
ID bson.ObjectId `json:"id" bson:"_id"`
...
}
UserModel struct {
...
// What do I store here? Is this an array of strings? An array of bson.ObjectID? Or an Array of OrderModel?
Orders []string `json:"orders" bson:"orders"`
Orders []bson.ObjectId `json:"orders" bson:"orders"`
Orders []OrderModel `json:"orders" bson:"orders"`
...
}
)
func (user *UserModel) PopulateOrders() {
orders := []OrderModel{}
// Query orders and assign to variable orders to then be assigned the the user Object
// {magic query here}
user.Orders = orders
}
In MongoDB, an array of ObjectIDs would be stored to reference the OrderModel documents. Later on, I have a function that will populate the Order documents like described above: PopulateOrders.
What is the best way for the case above?
I would use 2 separate fields, one for the slice of IDs, and one for the slice of lazily loaded objects.
Omit the lazily loaded object slice from saving. It could look like this:
type UserModel struct {
// ...
OrderIDs []bson.ObjectId `json:"orderIDs" bson:"orderIDs"`
Orders []OrderModel `json:"orders" bson:"-"`
// ...
}
Note that I intentionally did not exclude Orders from JSON serialization, as it is (may) be useful in JSON representation.