在Swift中使用swiftyJSON成功写入JSON到Realm DB

Question

我试图从JSON文件(使用swiftyJSON)写入一个Realm DB得到以下错误:

libc + + abi。dylib:以未捕获的NSException类型异常结束***由于未捕获异常'RLMException'而终止应用程序，原因:'无效值'{"vehicle":真的,"viewable":真的,"id": 0,"weapon":假的,"genres": "[幻想，一般]"，"name":";Car"}'初始化'Item'类型的对象:缺少键'id "

我的JSON文件结构如下:

[
{
"id": 0,
"name": "Car",
"genres": "[Fantasy, General]",
"viewable": true,
"weapon": false,
"vehicle": true
},
{
"id": 1,
"name": "Truck",
"genres": "[General]",
"viewable": true,
"weapon": false,
"vehicle": true
},
]

My Realm DB Class is:

class Item: Object {
@objc dynamic var id: Int = 0
@objc dynamic var name = ""
let genres = List<String>()
@objc dynamic var visable: Bool = false
@objc dynamic var weapon: Bool = false
@objc dynamic var vehicle: Bool = false

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

override static func indexedProperties() -> [String] {
return ["genre", "visable"]
}

}

，将JSON写入RealmDB的代码如下所示:

func jsonAdd() {
if let path = Bundle.main.path(forResource: "Data", ofType: "json") {
do {
let data = try Data(contentsOf: URL(fileURLWithPath: path), options: .mappedIfSafe)
let json = JSON(data)

for (index,subJson):(String, JSON) in json {

do {
try realm.write {

realm.create(Item.self, value: subJson, update: .modified)

}

} catch let error as NSError {
print("Unable to write")
print(error)
}

}

} catch {
print("Error")
}

}
}

我认为这个问题是一个JSON映射，但任何帮助将非常感谢将JSON写入到Realm DB，包括流派作为列表。

NB:在' write '函数之前，我已经设法使用以下代码(基于Realm文档)写到Realm DB，但似乎无法让它为我的JSON结构工作。

let newdata = "{"id": 0, "name": "Car", "genres": ["Fantasy","General"], "viewable": true, "weapon": false, "vehicle": true}".data(using: .utf8)!

let json = try! JSONSerialization.jsonObject(with: newdata, options: [])

谢谢!

Answer 1

通过以下方法解决:

1. 对JSON结构进行如下修改:

   [
   {
   "id": 0,
   "name": "Car",
   "genres": ["Fantasy", "General"],
   "viewable": true,
   "weapon": false,
   "vehicle": true
   },
   {
   "id": 1,
   "name": "Truck",
   "genres": ["Fantasy", "General"],
   "viewable": true,
   "weapon": false,
   "vehicle": true
   }
   ]
   

2. 创建一个新的流派对象，以更好地处理列表

   class Genres: Object {
   @objc dynamic var id = 0
   @objc dynamic var name = ""
   override static func primaryKey() -> String? {
   return "id"
   }
   }
   class Item: Object {
   @objc dynamic var id = 0
   @objc dynamic var name = ""
   var genres = List<Genres>()
   @objc dynamic var viewable: Bool = false
   @objc dynamic var weapon: Bool = false
   @objc dynamic var vehicle: Bool = false
   override static func primaryKey() -> String? {
   return "id"
   }
   override static func indexedProperties() -> [String] {
   return ["genres", "viewable"]
   }
   }
   

3)关键的是，在jsonADD函数中更新了代码以创建一个新的Item Object，然后在尝试写入Realm DB之前将JSON值映射到该对象:

for (key,subJson):(String, JSON) in jsonObjects {

let thisItem = Item()
thisItem.id = subJson["id"].intValue
thisItem.name = subJson["name"].stringValue
thisItem.visable = subJson["viewable"].boolValue
thisItem.weapon = subJson["weapon"].boolValue
thisItem.vehicle = subJson["vehicle"].boolValue

let genreArray = subJson["genres"].arrayValue

for genre in genreArray {
let string = genre.stringValue
let predicate = NSPredicate(format: "name = %@", string)

if let foundGenre = realm.objects(Genres.self).filter(predicate).first {
thisItem.genres.append(foundGenre)
}
}

do {
try realm.write {
realm.create(Item.self, value: thisItem, update: .modified)
}

} catch let error as NSError {
print("Unable to write")
print(error)
}
}