防止Realm在更新对象时覆盖属性 [英] Prevent Realm from overwriting a property when updating an Object

问题描述

我已经设置了REST API来实现iOS中对象的领域.但是我发现了在对象中创建收藏夹标志的问题.我创建了一个收藏夹布尔，但是每次从API更新对象时，它都会将收藏夹再次设置为默认false.在这里，我希望此标志不被更新，因为收藏夹仅存储在本地.我该如何实现?

I've setup a REST API to realm object in iOS. However I've found an issue with creating a favorite flag in my object. I've created a favorite bool, however everytime the object is updated from the API it sets the favorite to default false again. Here I want this flag to not be updated, since the favorite only is stored locally. How can I achieve this?

class Pet: Object{
    dynamic var id: Int = 1
    dynamic var title: String = ""
    dynamic var type: String = ""
    dynamic var favorite: Bool = false


    override class func primaryKey() -> String {
        return "id"
    }
}

创建或更新

let pet = Pet()
pet.id = 2
pet.name = "Dog"
pet.type = "German Shephard"


try! realm.write {
    realm.add(pet, update: true)
}

推荐答案

有两种解决方法:

1.使用被忽略的属性:

您可以告诉Realm某些属性不应保留.为了防止Realm保留您的favorite属性，您必须执行以下操作:

You can tell Realm that a certain property should not be persisted. To prevent that your favorite property will be persisted by Realm you have to do this:

class Pet: Object{
    dynamic var id: Int = 1
    dynamic var title: String = ""
    dynamic var type: String = ""
    dynamic var favorite: Bool = false

    override class func primaryKey() -> String {
        return "id"
    }

    override static func ignoredProperties() -> [String] {
       return ["favorite"]
   }
}

或者您可以

2.做部分更新

或者您可以在更新Pet对象时明确告诉Realm应该更新哪些属性:

Or you could tell Realm explicitly which properties should be updated when you update your Pet object:

try! realm.write {
  realm.create(Pet.self, value: ["id": 2, "name": "Dog", "type": "German Shepard"], update: true)
}

这样，favorite属性将不会更改.

This way the favorite property will not be changed.

结论

两种方法之间有一个很大的区别:

There is one big difference between the two approaches:

被忽略的属性:领域完全不会存储favorite属性.跟踪它们是您的责任.

Ignored Property: Realm won't store the favorite property at all. It is your responsibility to keep track of them.

部分更新::领域将存储收藏夹"属性，但不会更新.

Partial Update: Realm will store the 'favorite' property, but it won't be updated.

我想部分更新就是您要达到的目的.

I suppose that the partial updates are what you need for your purpose.

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