Question

我有一个包含以下NSManagedObjects的核心数据项目：

********************** FSDJump NSManaged Object

extension FSDJump {

@nonobjc public class func fetchRequest() -> NSFetchRequest<FSDJump> {
    return NSFetchRequest<FSDJump>(entityName: "FSDJump")
}

@NSManaged public var starSystem: String
@NSManaged public var starPos: NSArray
@NSManaged public var bodyName: String
@NSManaged public var jumpDist: Float
@NSManaged public var fuelUsed: Float
@NSManaged public var fuelLevel: Float
@NSManaged public var boostUsed: Bool
@NSManaged public var systemFaction: String
@NSManaged public var systemAllegiance: String
@NSManaged public var systemEconomy: String
@NSManaged public var systemGoverment: String
@NSManaged public var systemSecurity: String
@NSManaged public var powers: NSArray
@NSManaged public var powerplayState: String
@NSManaged public var timeStamp: String
@NSManaged public var factionState: String
@NSManaged public var factions: NSSet

}

// MARK：为派系生成的访问者扩展FSDJump {

@objc(addFactionsObject:)
@NSManaged public func addToFactions(_ value: Factions)

@objc(removeFactionsObject:)
@NSManaged public func removeFromFactions(_ value: Factions)

@objc(addFactions:)
@NSManaged public func addToFactions(_ values: NSSet)

@objc(removeFactions:)
@NSManaged public func removeFromFactions(_ values: NSSet)

}

**********************派系NSManaged Object

extension Factions {

@nonobjc public class func fetchRequest() -> NSFetchRequest<Factions> {
    return NSFetchRequest<Factions>(entityName: "Factions")
}

@NSManaged public var name: String
@NSManaged public var allegiance: String
@NSManaged public var factionState: String
@NSManaged public var government: String
@NSManaged public var influence: Float
@NSManaged public var fsdJump: FSDJump

}

在FSDJump和Factions之间定义了一对多的关系（即一个FSDJump可能有多个派系（反向关系定义为＆＃39; fsdJump＆＃39;）。

我使用以下代码来保存多个派系（如果存在的话），如果没有＆＃39;语句保存每个fsdJumpEvent。

                if fsdJumpEvent["Factions"].exists() {

                // save all of the Faction array objects in the variable arrayOfFactions
                let arrayOfFactions = fsdJumpEvent["Factions"]

                // create a newFaction managedObject to save the faction details to
                let newFaction = (Factions(context: contextTCCEDJ))
                for faction in arrayOfFactions {

                    // the following is strictly not necesary but it makes the code easier to read
                    // first allocate the values from faction to a local variable then allocate that variable to the newFaction managedObject
                    // Note faction is a tuple (string, JSON) so the construct 'faction.1' accesses the second value in the tuple
                    // 'faction.0' would access the first value in the tuple which is the array index "0", "1", "2", etc
                    let newFactionName = faction.1["Name"].string!
                    let newFactionState = faction.1["FactionState"].string!
                    let newFactionGovernment = faction.1["Government"].string!
                    let newFactionAllegiance = faction.1["Allegiance"].string!
                    let newFactionInfluence = faction.1["Influence"].float!

                    newFaction.name = newFactionName
                    newFaction.allegiance = newFactionAllegiance
                    newFaction.government = newFactionGovernment
                    newFaction.influence = newFactionInfluence
                    newFaction.factionState = newFactionState
                    // Add the new object to the context allowing it to be saved.
                    fsdJump.addToFactions(newFaction)
                    print("Faction added \(newFaction)")
                }
            }

代码似乎有效。它构建，运行并且print("Faction added \(newFaction)")语句按照预期存在时按照预期打印多个Faction，并根据我正在使用的源数据文件（JSON）打印。

我可以获取结果并在NSTableView中显示它们。我可以在没有任何问题的情况下为FSDJump托管对象加载数据，并在NSTableView中显示它。

获取代码为：

    // Function returns all of the Factions associated with the timeStamp related entry in FSDJumps using the fsdJump relationship
func eventFactionsFetchSavedDataFromPersistenStore (contextTCCEDJ: NSManagedObjectContext, timeStamp: String) -> [Factions] {
    var result = Array<Factions>()
    let localFetchRequest = Factions.fetchRequest() as NSFetchRequest
    localFetchRequest.predicate = NSPredicate(format:"fsdJump.timeStamp == '\(timeStamp)'")
    do {
        result = try contextTCCEDJ.fetch(localFetchRequest)
    } catch {
        print("Error in returning Factions event saved data from the persistent store")
    }
   print(result.count)
    for reSult in result {
    print(reSult.fsdJump.timeStamp)
    }
    return result
}

然而，它似乎只能保存最后一个阵营＆＃39;对于每个关系 - 而不是for faction in arrayOfFactions循环中显示的多个派系。因为fetch语句每次获取只返回一个Faction。即使我删除了谓词语句，它也会返回所有已保存的派系，但每个fsdJumpEvent只保存一个，而不是print语句标识的多个派系。

我已经尝试了所有我能想到的东西。我无法找到与此特定问题相关的先前问题。

我使用的是＆＃39; addToFactions＆＃39;功能不正确？

感谢任何帮助。

（是的 - 对于任何Elite Dangerous粉丝，我正在编写一个macOS应用程序来解析我的日志文件作为我的Windows版精英危险的伴侣应用程序。）

Answer 1

您正在newFaction循环之外创建一个新的for faction in arrayOfFactions实例。因此，每次循环运行时都会使用单newFaction，只是为其分配新值（覆盖以前的值），从而导致最后一组值结束。因此，你会看到一个单一派系的最后一个＆＃39;一组价值观。移动线： Let newFaction = Factions(context: contectTCCEDJ) 在for in循环的内部（开头）。

编辑：您正在将一个阵营添加到一个集合（根据定义需要唯一的实体），因此您当前所做的只是每次重新添加相同的阵营而不是新阵营。 To-many关系指向Set。

核心数据一对多关系未正确保存/按预期

1 个答案: