复合主键 realm/swift

Question

我是 swift 领域的新手。我想制作一个复合主键，当我尝试这样的事情时：

class DbLocation : Object {
 dynamic var id = 0
 dynamic var tourId = 0

 dynamic var uuid : String  {
    return "\(id)\(tourId)"
 }

 override static func primaryKey() -> String? {
    return "uuid"
 }
}

我收到此错误： '主键属性 'uuid' 在对象 'DbLocation'

上不存在

谁能帮我举例说明如何创建复合主键？

Answer 1

1.0.1+ 领域：

class DbLocation: Object{
    dynamic var id = 0
    dynamic var tourId = 0
    dynamic var compoundKey = ""

    override static func primaryKey() -> String? {
        return "compoundKey"
    }

    func setup(id: Int, tourId: Int){
        self.id = id
        self.tourId = tourId
        self.compoundKey = compoundKeyValue()
    }

    func compoundKeyValue() -> String {
        return "\(id)\(tourId)"
    }
}

用法示例：

let location = DbLocation()
location.setup(id: 0, tourId: 1) 
print(location.compoundKey) // "01"

当然，您可以尝试在 id 和 tourId 上使用各种 didSet 侦听器，以确保每次更改值时都能正确重写 compoundKey。

pre-1.0.1 领域：

class DbLocation: Object {
    dynamic var id = 0
    dynamic var tourId = 0

    func setCompoundID(id: Int) {
        self.id = id
        compoundKey = compoundKeyValue()
    }

    func setCompoundTourId(tourId: Int) {
        self.tourId = tourId
        compoundKey = compoundKeyValue()
    }

    dynamic lazy var compoundKey: String = self.compoundKeyValue()

    override static func primaryKey() -> String? {
        return "compoundKey"
    }

    func compoundKeyValue() -> String {
        return "\(id)\(tourId)"
    }
}

自定义设置器确保 compoundKey 始终更新，惰性关键字确保您第一次访问它时，它将派生自您已经设置的内容。

在讨论此问题的 this thread 中找到有关此主题的更多信息。

Answer 2

简单地创建一个新的属性，其值设置为您希望作为复合主键的其他感兴趣的属性。

class DbLocation: Object {
            dynamic var id = 0
            dynamic var tourId = 0
            dynamic var compoundKey: String? = ""

        override static func primaryKey() -> String? {
                return "compoundKey"
            }
        }
    let location = DbLocation()
    location.tourId = 1
    location.id = 5
    location.compoundKey = "\(id) \(tourId)"

Answer 3

对于 Swift 和 Realm 的最新版本，我会做这样的事情。

dynamic private var compoundKey: String = ""

required convenience init?(map: Map) {
  self.init()
  if let firstValue = map.JSON["firstValue"] as? String,
    let secondValue = map.JSON["secondValue"] as? Int {
    compoundKey = firstValue + "|someStringToDistinguish|" + "\(secondValue)"
  }
}

复合主键 realm/swift

composite primary key realm/swift

realm

ios

swift