swift – Realm.create会用同一个主键更新对象吗？

发布时间：2020-12-14 02:26:25 所属栏目：百科来源：网络整理

导读：我只是好奇,如果我调用realm.create,它会从领域结果自动更新领域对象吗？ // Assuming a "Book" with a primary key of `1` already exists.try! realm.write {realm.create(Book.self,value: ["id": 1,"price": 9000.0],update: true)// the book's `title`

我只是好奇,如果我调用realm.create,它会从领域结果自动更新领域对象吗？

// Assuming a "Book" with a primary key of `1` already exists.
try! realm.write {
realm.create(Book.self,value: ["id": 1,"price": 9000.0],update:   true)
// the book's `title` property will remain unchanged.
}

目前看起来我需要再次从领域读取以获取最新的对象.如果我错了,请纠正我.

谢谢

是的,在调用Realm.create(_：value：update :)时指定update：true将导致更新现有对象.

这是基于您提供的代码的片段,演示了这一点：

class Book: Object {
    dynamic var id = ""
    dynamic var title = ""
    dynamic var price = 0.0

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


let realm = try! Realm()
let book = Book(value: ["1","To Kill a Mockingbird",9.99])
try! realm.write {
    realm.add(book)
}

let results = realm.allObjects(ofType: Book.self)

try! realm.write {
    realm.createObject(ofType: Book.self,populatedWith: ["id": "1","price": 7.99],update: true)
}

print(book)
print(results)

此代码生成以下输出：

Book {
    id = 1;
    title = To Kill a Mockingbird;
    price = 7.99;
}
Results<Book> (
    [0] Book {
        id = 1;
        title = To Kill a Mockingbird;
        price = 7.99;
    }
)

如您所见,现有对象的price属性已更新为新值.

（编辑：李大同）

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