iOS-Swift：将NSManagedObject序列化为JSON（使用关系） [英] iOS-Swift : Serialize a NSManagedObject to JSON (with relationships)
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问题描述
在花了太多时间寻找最佳做法后，我再次要求您提供一些帮助，希望我不是唯一一个与此有关的人：
import Foundation
import CoreData
class Credential ：NSManagedObject {
@NSManaged var credentialArrivalDate：String？
@NSManaged var credentialBarCode：String？
@NSManaged var credentialComment：String？
@NSManaged var credentialCountCheckIn：Int
@NSManaged var credentialCountCheckOut：Int
@NSManaged var credentialDepartureDate：String？
@NSManaged var credentialId：String？
@NSManaged var credentialIsArrived：Bool
@NSManaged var credentialIsCheckedOut：Bool
@NSManaged var credentialIsHost：Bool
@NSManaged var credentialLastModificationDate：String？
@NSManaged var credentialMemberControlled：String？
@NSManaged var credentialNumberOfPeople：Int
@NSManaged var credentialRSVP：Int
@NSManaged var credentialTypeId：String？
@NSManaged var credentialTypeName：String？
@NSManaged var credentialZoneId：String？
@NSManaged var credentialZoneName：String？
@NSManaged var credentialHosts：Set< Host> ;?
@NSManaged var credentialMember：Member
@NSManaged var credentialExtensionFields：Set< ExtensionFields> ;?
@NSManaged var credentialDeltaFirstCheckIn：String？
@NSManaged var credentialDeltaFirstCheckOut：String？
@NSManaged var credentialIsCheckedIn：Bool
}
与成员实体的关系：
import Foundation
import CoreData
类成员： NSManagedObject {
@NSManaged var memberCompany：String
@NSManaged var memberEMail：String
@NSManaged var memberFirstName：String
@NSManaged var memberId：String
@NSManaged var memberJob：String
@NSManaged var memberLastModificationDate：String
@NSManaged var memberLastName：String
@NSManaged var memberPhoneNumber：String
@NSManaged var memberTitle：String
@NSManaged var memberCredential：Credential
}
我想做什么是使用NSJSONSerialization.dataWithJSONObject将我的Credential对象序列化为JSON以生成我的JSON并POST到服务器。
但是，序列化我的对象时出现错误，我相信这是因为我的对象不尊重这一点（从苹果文档）：
可以转换为JSON的对象必须具有以下属性：
- 顶层对象是NSArray或NSDictionary。
- 所有对象都是NSString，NSNumber， NSArray，NSDictionary或NSNull。
- 所有字典键都是NSString的实例。
- 数字不是NaN或无穷大。
那么如何将我的对象序列化为JSON？我应该找到某种方法将会员转换为字典，然后尝试找到一种方法来设置这个字典作为我与证书的关系的值？
有我错过了处理它的内置映射器？
对不起，如果不清楚，任何帮助将是非常好的。
提前，谢谢。
Hugo
>：
如答案中所示，我试图获取字典而不是NSManagedObject，但记录的字典是空的（但是，相同的代码工作非常简单类有几个字符串属性，没有关系），这里是代码：
/ ********* **********************
TEST：Fetch字典，而不是NSManagedObject
* /
// create Credential entity
let newCredential = NSEntityDescription.insertNewObjectForEntityForName（Credential，inManagedObjectContext：self.managedObjectContext！）as！ Credential
//创建凭据实体
let newMember = NSEntityDescription.insertNewObjectForEntityForName（Member，inManagedObjectContext：self.managedObjectContext！）as！会员
//实例化一些字段
newCredential.credentialId =44444
newMember.memberFirstName =TEST
//设置关系
newCredential.credentialMember = newMember
//检索currentCredential
让requestGuest = NSFetchRequest（entityName：Credential）
//获取字典NSManagedObject
requestGuest.resultType = NSFetchRequestResultType.DictionaryResultType
let fetchedGuest =（managedObjectContext！.executeFetchRequest（requestGuest，error：nil））！ //不需要在这里投？
println（fetchedGuest.description）
/ ************************* **** /
解决方案
没有成功与一对一和一对多的关系。所以我写了一个解析器来将托管对象转换为字典和数组。
//在xCode 6.4上测试 - Swift 1.2
让requestGuest = NSFetchRequest（entityName： Credential）
let fetchedGuest =（managedObjectContext！.executeFetchRequest（requestGuest，error：nil））！
let dataInArr：NSArray = ManagedParser.convertToArray（fetchedGuest）;
NSLog（dataInArr \（dataInArr））;
// -
//
// ManagedParser.swift
//由Shoaib于7/29/15创建。
//
import UIKit
import CoreData
class ManagedParser：NSObject {
class func convertToArray （managedObjects：NSArray ?, parentNode：String？= nil） - > NSArray {
var rtnArr：NSMutableArray = NSMutableArray（）;
// -
如果let managedObjs：[NSManagedObject] = managedObjects as？ [NSManagedObject] {
for managedObject：NSManagedObject in managedObjs {
rtnArr.addObject（self.convertToDictionary（managedObject，parentNode：parentNode））;
}
}
return rtnArr;
} //F.E。
class func convertToDictionary（managedObject：NSManagedObject，parentNode：String？= nil） - > NSDictionary {
var rtnDict：NSMutableDictionary = NSMutableDictionary（）;
// -
let entity：NSEntityDescription = managedObject.entity;
让属性：[String] =（entity.propertiesByName as NSDictionary）.allKeys as！ [串];
// -
let parentNode：String = parentNode？ managedObject.entity.name !;
for property：属性中的字符串{
if（property.caseInsensitiveCompare（parentNode）！= NSComparisonResult.OrderedSame）
{
让值：AnyObject？ = managedObject.valueForKey（property）;
// -
如果let set：NSSet = value as？ NSSet {
rtnDict [property] = self.convertToArray（set.allObjects，parentNode：parentNode）;
} else if let vManagedObject：NSManagedObject = value as？ NSManagedObject {
if（vManagedObject.entity.name！= parentNode）{
rtnDict [property] = self.convertToDictionary（vManagedObject，parentNode：parentNode）;
}
} else if let vData：AnyObject = value {
rtnDict [property] = vData;
}
}
}
return rtnDict;
} //F.E。
} // CLS END
After spending too much time trying to find the best practices, here I am once again asking for some help, hoping I am not the only one struggling with this :
I have NSManaged Objects like these :
import Foundation
import CoreData
class Credential: NSManagedObject {
@NSManaged var credentialArrivalDate: String?
@NSManaged var credentialBarCode: String?
@NSManaged var credentialComment: String?
@NSManaged var credentialCountCheckIn: Int
@NSManaged var credentialCountCheckOut: Int
@NSManaged var credentialDepartureDate: String?
@NSManaged var credentialId: String?
@NSManaged var credentialIsArrived: Bool
@NSManaged var credentialIsCheckedOut: Bool
@NSManaged var credentialIsHost: Bool
@NSManaged var credentialLastModificationDate: String?
@NSManaged var credentialMemberControlled: String?
@NSManaged var credentialNumberOfPeople: Int
@NSManaged var credentialRSVP: Int
@NSManaged var credentialTypeId: String?
@NSManaged var credentialTypeName: String?
@NSManaged var credentialZoneId: String?
@NSManaged var credentialZoneName: String?
@NSManaged var credentialHosts: Set<Host>?
@NSManaged var credentialMember: Member
@NSManaged var credentialExtensionFields: Set<ExtensionFields>?
@NSManaged var credentialDeltaFirstCheckIn: String?
@NSManaged var credentialDeltaFirstCheckOut: String?
@NSManaged var credentialIsCheckedIn: Bool
}
I have a relationship with a Member Entity :
import Foundation
import CoreData
class Member: NSManagedObject {
@NSManaged var memberCompany: String
@NSManaged var memberEMail: String
@NSManaged var memberFirstName: String
@NSManaged var memberId: String
@NSManaged var memberJob: String
@NSManaged var memberLastModificationDate: String
@NSManaged var memberLastName: String
@NSManaged var memberPhoneNumber: String
@NSManaged var memberTitle: String
@NSManaged var memberCredential: Credential
}
What I am trying to do is to serialize my Credential object to JSON using NSJSONSerialization.dataWithJSONObject to generate my JSON and POST it to a Server.
However, I've got an error while serializing my object, and I believe this is because my object does not respect this (from Apple documentation) :
An object that may be converted to JSON must have the following properties:
- The top level object is an NSArray or NSDictionary.
- All objects are instances of NSString, NSNumber, NSArray, NSDictionary, or NSNull.
- All dictionary keys are instances of NSString.
- Numbers are not NaN or infinity.
So how can I Serialize my Object to JSON ? Should I find some way to convert a Member to a Dictionary, then try to find a way to set this dictionary as the value for my relationship with a credential ?
Have I missed a built-in mapper that handles it ?
I am sorry if that is not clear but any help would be very nice.
In advance, thank you.
Hugo
EDIT :
As suggested in an answer, I tried to fetch a dictionary instead of a NSManagedObject but the logged dictionary is empty (however, the same code worked for a very simple class with a few string attributes and no relationship), here is the code :
/*******************************
TEST : Fetch dictionary instead of NSManagedObject
*/
// create Credential entity
let newCredential = NSEntityDescription.insertNewObjectForEntityForName("Credential", inManagedObjectContext: self.managedObjectContext!) as! Credential
// create Credential entity
let newMember = NSEntityDescription.insertNewObjectForEntityForName("Member", inManagedObjectContext: self.managedObjectContext!) as! Member
// instanciate some fields
newCredential.credentialId = "44444"
newMember.memberFirstName = "TEST"
// set the relationship
newCredential.credentialMember = newMember
// retrieve currentCredential
let requestGuest = NSFetchRequest(entityName: "Credential")
// get a dictionary instead of NSManagedObject
requestGuest.resultType = NSFetchRequestResultType.DictionaryResultType
let fetchedGuest = (managedObjectContext!.executeFetchRequest(requestGuest, error:nil))! // no need to cast here ?
println(fetchedGuest.description)
/*******************************/
解决方案
I tried the same but could not get succeed with one to one and one to many relationships. So I wrote a parser to convert managed objects to dictionary and array. You may use it;
//Tested on xCode 6.4 - Swift 1.2
let requestGuest = NSFetchRequest(entityName: "Credential")
let fetchedGuest = (managedObjectContext!.executeFetchRequest(requestGuest, error:nil))!
let dataInArr:NSArray = ManagedParser.convertToArray(fetchedGuest);
NSLog("dataInArr \(dataInArr)");
//--
//
// ManagedParser.swift
// Created by Shoaib on 7/29/15.
//
import UIKit
import CoreData
class ManagedParser: NSObject {
class func convertToArray(managedObjects:NSArray?, parentNode:String? = nil) -> NSArray {
var rtnArr:NSMutableArray = NSMutableArray();
//--
if let managedObjs:[NSManagedObject] = managedObjects as? [NSManagedObject] {
for managedObject:NSManagedObject in managedObjs {
rtnArr.addObject(self.convertToDictionary(managedObject, parentNode: parentNode));
}
}
return rtnArr;
} //F.E.
class func convertToDictionary(managedObject:NSManagedObject, parentNode:String? = nil) -> NSDictionary {
var rtnDict:NSMutableDictionary = NSMutableDictionary();
//-
let entity:NSEntityDescription = managedObject.entity;
let properties:[String] = (entity.propertiesByName as NSDictionary).allKeys as! [String];
//--
let parentNode:String = parentNode ?? managedObject.entity.name!;
for property:String in properties {
if (property.caseInsensitiveCompare(parentNode) != NSComparisonResult.OrderedSame)
{
let value: AnyObject? = managedObject.valueForKey(property);
//--
if let set:NSSet = value as? NSSet {
rtnDict[property] = self.convertToArray(set.allObjects, parentNode: parentNode);
} else if let vManagedObject:NSManagedObject = value as? NSManagedObject {
if (vManagedObject.entity.name != parentNode) {
rtnDict[property] = self.convertToDictionary(vManagedObject, parentNode: parentNode);
}
} else if let vData:AnyObject = value {
rtnDict[property] = vData;
}
}
}
return rtnDict;
} //F.E.
} //CLS END
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