Grails GORM：有许多相同的域类

只是想知道是否有人可以建议域类模式应该是什么。我有一个名为Category的域类，但是可以有具有相同域（Category）的子类别。例如，一台烤面包机可以归入厨房类、小家电子类

class Category {
   static hasMany = [appliances: Appliance, categories: Category] 
   String name
}

class Appliance {
   static belongsTo = Category
   static hasMany = [categories: Category]
}

---

需要对Appliance域类进行一些小调整。猜猜看！！：）

对于

类别

，我们不需要在

设备

中使用hasMany关系。这种关系是这样的：

Category --> SubCategory (type of Category) --> Appliance

设备

既属于父类别

，也属于

子类别

，而子类别本身又属于

类别

。因此，在设备中，保持关系就足够了

改用：

class Appliance {
   static belongsTo = Category
   String name
}

class Category {
    String name
    static hasMany = [appliances: Appliance, subCategories: Category]
}

下面是一个可以让您更好地理解事物的测试用例：

//Category
def kitchen = new Category(name: "Kitchen")
kitchen.save()

//Appliance
def toaster = new Appliance(name: "Toaster")
kitchen.addToAppliances(toaster)
kitchen.save()

//Sub Categories
def electrical = new Category(name:  "Electrical")
//Electrical category is a sub category of Kitchen
kitchen.addToSubCategories(electrical)

//Toaster is an appliance of Category Kitchen and Sub Category Electrical
electrical.addToAppliances(toaster)
kitchen.save()

assert kitchen
assert toaster
assert electrical

assert kitchen.appliances.size() == 1
kitchen.appliances.each{assert it.name == 'Toaster'}

assert kitchen.subCategories.size() == 1
kitchen.subCategories.each {assert it.name == 'Electrical'}

assert electrical.appliances.size() == 1
electrical.appliances.each {assert it.name == 'Toaster'}

---

如果仍不清楚，请告知。

谢谢您的详细回答。我明白你的意思，就我的情况而言，我希望能够添加多个类别的产品，而不仅仅是一个类别。例如：厨房和小家电子类别中的烤面包机。也是电气类的烤面包机。