删除 Realm 对象所有未来出现的正确方法是什么? [英] What's the correct way to delete all future occurrences of a Realm object?
问题描述
目前,我正在使用此代码删除所有未来的重复交易:
Currently, I am using this code to delete all future repeat transactions:
let futureRecurringTransactions = self.transactions.filter(NSPredicate(format: "transactionDescription == %@ && transactionDate >= %@ && transactionCategory == %@", transaction!.transactionDescription!, transaction!.transactionDate as CVarArg, transaction!.transactionCategory!))
for transaction in futureRecurringTransactions {
try! self.realm.write {
self.realm.delete(transaction)
}
}
这是我的 Realm 数据模型:
Here is my Realm data model:
import RealmSwift
class Transaction: Object {
@objc dynamic var transactionDescription: String? = nil
@objc dynamic var transactionAmount = 0.0
@objc dynamic var transactionDate = Date()
@objc dynamic var transactionCategory: Category? = nil
@objc dynamic var repeatInterval = ""
@objc dynamic var isCleared = false
@objc dynamic var transactionName = ""
@objc dynamic var transactionID = UUID().uuidString
convenience init(theDate: Date) {
self.init()
self.transactionDate = theDate
}
override static func primaryKey() -> String? {
return "transactionID"
}
}
代码有效,但感觉我的做法是业余的和笨拙的.有没有更准确、更合适的更好的方法?
The code works, but it feels like the way I'm doing it is amateur and clunky. Is there a better way that is more accurate and proper?
我认为使用 transactionID 可能会很好,但每个交易都有一个唯一的 transactionID,所以我不确定它是如何工作的.
I thought it might be good to utilize the transactionID , but each transaction has a unique transactionID, so I'm not sure how that would work.
推荐答案
我通常做的是为要放置在集合上的每个约束创建一个唯一的 NSPredicate.您可以混合和匹配每个谓词以形成一组独特的过滤器.例如:
What I typically do is create a unique NSPredicate for each constraint you want to place on the collection. You can mix and match each predicate to form a unique set of filters. For example:
extension NSPredicate {
static func transactionDescriptionEqualTo(_ description: String?) -> NSPredicate {
if let description = description {
return .init(format: "transactionDescription == %@", description)
}
return .init(format: "transactionDescription == nil")
}
static func transactionCategoryEqualTo(_ category: Category?) -> NSPredicate {
if let category = category {
return .init(format: "transactionCategory == %@", category)
}
return .init(format: "transactionCategory == nil")
}
static func transactionDateIsAfter(_ date: Date) -> NSPredicate {
return .init(format: "transactionDate >= %@", date as NSDate)
}
static func transactionIDNotEqualTo(_ id: String) -> NSPredicate {
return .init(format: "transactionID != %@", id)
}
static func futureRepeats(of transaction: Transaction) -> NSPredicate {
return NSCompoundPredicate(andPredicateWithSubpredicates: [
.transactionDescriptionEqualTo(transaction.transactionDescription),
.transactionCategoryEqualTo(transaction.transactionCategory),
.transactionDateIsAfter(transaction.transactionDate),
.transactionIDNotEqualTo(transaction.transactionID),
])
}
}
另请注意,您不需要遍历结果.您可以像这样删除结果中的所有对象:
Also note that you don't need to loop over the results. You can delete all objects in the results like this:
let realm = try Realm()
try realm.write {
realm.delete(transactions.filter(.futureRepeats(of: transaction)))
}
最后,将 transactionID 作为约束包含在内是一个好主意.否则原始交易将包含在结果中.
Lastly, it's a good idea to include the transactionID as a constraint. Otherwise the original transaction will be included in the results.
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