单引用多个对象
关于如何在OO / DB关系中做什么，我有点...
这是DB模型：
CREATE TABLE User
Id
CREATE TABLE Location
userId
// EDIT oups, wrong !
// placeId
// Should be :
seatId
CREATE TABLE Game
locationId
class User
{
private Location locations[]; // need this for several reasons...
public function loadFromDatabase()
{
// Load data from DB
// ...
result = DB::query("SELECT Id FROM Locations WHERE userId="+this->Id);
foreach(result)
{
l = new Location();
l->loadFromDatabase(result);
locations[] = l;
}
}
}
class Location
{
private User user;
public function loadFromDatabase()
{
...
}
}
class Game
{
private Location location;
public loadFromDatabase()
{
/*
Here comes the problem :
how to have a reference to a location
created by the User class ?
*/
}
}
没有找到相关结果
已邀请:
1 个回复
你换
表中有一个，我假设有一个表描述了实际的位置，而表只是表示用户和地点之间的多对多映射。 在这种情况下，不需要有自己的，也不需要是一个类，但确实如此。 要从数据库中仅加载每个对象的一个实例，请将实例缓存在每个类内的静态映射中。class Place { // Static private static Place loadedPlaces[]; public static function get(id) { if (!loadedPlaces[id]) { loadedPlaces[id] = new Place(id); loadedPlaces[id]->loadFromDatabase(); } return loadedPlaces[id]; } // Non-static private id; public function loadFromDatabase() { // ... } }class User { public function loadFromDatabase() { result = DB::query("SELECT placeId FROM Locations WHERE userId="+this->Id); foreach(result) { places[] = Place::get(result); } } } class Game { public function loadFromDatabase() { place = Place::get(place); } }