Alamofire, Objectmapper, Realm: Nested Objects

问题:

I'm using Alamofire, Objectmapper, Realm and everything is working beside one thing: I can't map nested objects.

class Voting: Object, Mappable {      dynamic var votingID: String = ""     dynamic var question: String = ""     var votingOptions = List()      required convenience init?(_ map: Map) {         self.init()     }      func mapping(map: Map) {         votingID  String {         return "votingID"     }    }  class VotingOption: Object, Mappable{      dynamic var optionID: String = ""     dynamic var text: String = ""       required convenience init?(_ map: Map) {         self.init()     }      func mapping(map: Map) {         optionID  String {         return "optionID"     }    } 

The JSON that I'm trying to map is:

{     "Voting": [         {             "question": "Which option do yo prefer?",             "id": "7f073efd-6f3d-43f2-9fe4-5cad683b77a2",             "votingOptions": [                 {                     "optionText": "Option 3",                     "id": "3bc0a618-8791-4862-a7fd-5f2df464697d"                 },                 {                     "optionText": "Option 1",                     "id": "84c6a830-814b-40c8-a252-c074be5d689a"                 },                 {                     "optionText": "Option 2",                     "id": "8872ef6f-fc70-445a-802e-d39944006467"                 }             ]         }     ] } 

The mapping funktion in VotingOption never gets called.

回答1:

The old ListTransform solution no longer works in Swift 3.

This is what I'm using now; put this in a file called, ListExtensions.swift, for example.

import Foundation import ObjectMapper import RealmSwift  /// Maps object of Realm's List type func (left: List, right: Map) {     var array: [T]?      if right.mappingType == .toJSON {         array = Array(left)     }      array 

This allows you can simply use it like this:

class Parent: Object, Mappable {     dynamic var id: Int = 0     var children = List()      required convenience init?(_ map: Map) {         self.init()     }      func mapping(map: Map) {         id 

回答2:

The problem you're seeing is due to ObjectMapper having no knowledge of Realm's List type. It is not aware that it is a collection type, and that it must be mutated in place rather than being assigned to. You can see discussion of this, including some suggested workarounds, in ObjectMapper GitHub issue #143.

Note also that any List properties on Object subclasses should be declared with let rather than var.

回答3:

class ListTransform : TransformType where T:Mappable {     typealias Object = List     typealias JSON = [AnyObject]      let mapper = Mapper()      func transformFromJSON(_ value: Any?) -> Object? {         let results = List()         if let objects = mapper.mapArray(JSONObject: value) {             for object in objects {                 results.append(object)             }         }         return results     }      func transformToJSON(_ value: Object?) -> JSON? {         var results = [AnyObject]()         if let value = value {             for obj in value {                 let json = mapper.toJSON(obj)                 results.append(json as AnyObject)             }         }         return results     } } 

Then in your model something like this.

class Parent: Object, Mappable {     dynamic var id: Int = 0     var children = List()      required convenience init?(_ map: Map) {         self.init()     }      func mapping(map: Map) {         id ())     } } 

回答4:

You can extend ObjectMapper for Realm.List type with a operator function like as:

public func (left: List, right: Map) {   if right.mappingType == MappingType.FromJSON {     if let value = right.currentValue {       left.removeAll()       if let json = value as? [[String : AnyObject]] {         let objs = RealmS().add(T.self, json: json)         left.appendContentsOf(objs)       }     }   } } 

Try yourself.

ObjectMappper + Realm List type

文章来源: Alamofire, Objectmapper, Realm: Nested Objects