Objectmapper: Subclassing and Realm

[jpmcglone]

I have this class

import ObjectMapper
import RealmSwift

class Base: Object, Mappable {
    dynamic var id: String?
    dynamic var objectType: String?
    dynamic var createdAt: String? // TODO: make sure this gets converted to an NSDate!

    required convenience init?(_ map: Map) {
        self.init()
    }

    func mapping(map: Map) {
        id <- map["id"]
        createdAt <- map["created_at"]
        objectType <- map["_class"]
    }
}

and then I subclass it here:

import ObjectMapper
import RealmSwift

class User: Base {
    dynamic var username: String?
    dynamic var bio: String?

    override func mapping(map: Map) {
        super.mapping(map)
        username <- map["username"]
        bio <- map["bio"]
    }
}

And it won't build. Some reason, I'm getting this error:
<unknown>:0: error: must call a designated initializer of the superclass 'Base'

worries me >_<

Is there something I'm missing??

[jpmcglone]

Ok, so I figured out that every subclass (we have many) needs to have these requireds

    // MARK: - Requireds
    required init() { super.init() }
    required init?(_ map: Map) { super.init() }
    required init(value: AnyObject, schema: RLMSchema) { super.init(value: value, schema: schema) }
    required init(realm: RLMRealm, schema: RLMObjectSchema) { super.init(realm: realm, schema: schema) }

I get this is probably more a swift question now, and not a realm or objectmapper question, but can someone explain to me why I need to do this in every subclass? Or is there a way to get it from super? Calling only super.init on everything makes little sense

[jpsim]

This shouldn't be necessary if you remove the required from the required convenience init?(_ map: Map) declaration.

[jpmcglone]

Thanks! I will try this. If it works, you just made the code look 1000x cleaner.

[jpmcglone]

Well damn. Initializer requirement 'init' can only be satisfied by arequiredinitializer in non-final class 'Base'

[jpmcglone]

Unrelated: it's nice to meet a fellow JP.

[liuxuleidota]

Should subclass add an initializer?
eg. required convenience init?(_ map: Map) { self.init() }
Since I got a build error without doing that.
must call a designated initializer of the superclass

[robbiet480]

Any updates on this? Hitting the same error that @jpmcglone was getting about Initializer requirement...

[maasim94]

I have exact same error following help me to solve it, i'm not sure if it is correct way but it solves my problem
basically i don't call super.init in child class
//Base class

class CookJson:Object, Mappable {
dynamic var cookID:Int = 0
dynamic var cuts_id:Int = 0
dynamic var doneness:String = ""
dynamic var duration:String = ""
dynamic var tempreature:String = ""
override class func primaryKey() -> String {
return "cookID"
}
required convenience init?(_ map: Map) {
self.init()
}
func mapping(map: Map) {
cookID <- map["id"]
cuts_id <- map["cuts_id"]
doneness <- map["doneness"]
duration <- map["duration"]
tempreature <- map["tempreature"]
}
}
//Child class
class CookbyWeightJson:CookJson {
dynamic var high_weight:String = ""
dynamic var low_weight:String = ""
required convenience init?(_ map: Map) {
self.init()
}
override func mapping(map: Map) {
super.mapping(map)
high_weight <- (map["high_weight"])
low_weight <- map["low_weight"]
}
}

[robbiet480]

@maasim94 Just tried your code and got this error:

<unknown>:0: error: must call a designated initializer of the superclass 'Entity'
/Users/robbiet480/Repos/HomeAssistant/HomeAssistant/Entity.swift:77:26: note: convenience initializer is declared here
    required convenience init?(_ map: Map) {

[chrixrux]

Any updates on this topic? I'm getting the same error as @robbiet480

[geodesicer]

I use the following in my base class (called RBase), and in addition this solves AFAIK the update problem in writing a JSON from within a Realm write:

class RBase: Object, Mappable {

dynamic var filename = ""
dynamic var id = NSUUID().UUIDString
dynamic var idz = "" {
    didSet {
        idz = id
    }
}
dynamic var rType: String = ""

internal override init(value: AnyObject)
{
    super.init(value: value)
    rType = String(self.dynamicType)
}

required init() {
    super.init()
    rType = String(self.dynamicType)
}

required init?(_ map: Map) {
    if let theType = map.JSONDictionary["rType"] {
        if let theString = theType as? String {
            if theString == String(self.dynamicType) {
                super.init()
                return
            }
        }
    }

    return nil
}

required init(value: AnyObject, schema: RLMSchema) {
    super.init(value: value, schema: schema)
    rType = String(self.dynamicType)
}

required init(realm: RLMRealm, schema: RLMObjectSchema) {
    super.init(realm: realm, schema: schema)
    rType = String(self.dynamicType)
}

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

func mapping(map: Map) {
    filename <- map["filename"]
    rType <- map["rType"]
    idz <- map["id"]
    idz <- map["idz"]
}

}

[MadeByDouglas]

Anyone find a clean solution to this?

[jpmcglone]

We're still just adding the required inits unfortunately. At least I can make it a copy paste solution that goes at the bottom (or top) of the file. /shrug

[MadeByDouglas]

ok, looks like ill do that too then, cant find a better alternative

[tristanhimmelman]

I have just released v1.5.0. This update now allows ObjectMapper to be implemented purely within an extension. Using the updated StaticMappable protocol, you will only need to implement the following two functions:

mutating func mapping(map: Map)
static func objectForMapping(map: Map) -> BaseMappable?

This should make working with Realm significantly easier. Hope this helps!

[jpmcglone]

I'll try it some time this week @tristanhimmelman

[robbiet480]

Can the 1.5.0 changes be merged into the Swift 3 branch?

[tristanhimmelman]

@robbiet480 they already have been :)

[robbiet480]

Whoops, didn't notice, just saw the merge commit. Thanks @tristanhimmelman! I plan to test this out at some point today and will report back.

[robbiet480]

@tristanhimmelman Looks like this change may have broken AlamofireObjectMapper.

If you are going to go fix that, I'd suggest that https://github.com/tristanhimmelman/AlamofireObjectMapper/pull/137 gets merged beforehand to fix the Alamofire class renaming that occurred in the last few days.

[tristanhimmelman]

@robbiet480 I have updated AlamofireObjectMapper to work with the latest Alamofire using Xcode 8 GM. Let me know if you are still having problems

[robbiet480]

@tristanhimmelman Had to make another change to get it working, see https://github.com/tristanhimmelman/AlamofireObjectMapper/pull/143

[robbiet480]

@tristanhimmelman I still need to keep the required inits in. Otherwise I get fixable errors that they are missing. So it appears StaticMappable didn't change anything :(

[tristanhimmelman]

@robbiet480 StaticMappable and Realm are working fine for me. See the model I am testing for AlamofireObjectMapper

class Forecast: Object, StaticMappable {
    dynamic var day = ""
    dynamic var temperature: Int = 0
    dynamic var conditions = ""

    class func objectForMapping(_ map: Map) -> BaseMappable? {
        return Forecast()
    }

    func mapping(_ map: Map) {
        day <- map["day"]
        temperature <- map["temperature"]
        conditions <- map["conditions"]
    }
}

I'm not sure why you are getting errors wrt the initializers. Perhaps you can post your class so we can help you out.

[robbiet480]

@tristanhimmelman I got it working! It's because I had a custom init function I wrote in my base Entity class. Once I removed that everything worked. Thanks!

[tristanhimmelman]

Closing this ticket as the issues should be resolved by using the updated StaticMappable protocol

[mitchtreece]

@tristanhimmelman Still trying to get this working with Realm. I'm using StaticMappable like this:

class Parent: Object, StaticMappable {

    dynamic var uid: String = ""

    static func objectForMapping(map: Map) -> BaseMappable? {
        return Parent()
    }

    func mapping(map: Map) {
        uid <- map["uid"]
    }

}

class Child: Parent {

    dynamic var name: String = ""

    override func mapping(map: Map) {
        super.mapping(map: map)
        name <- map["name"]
    }

}

Everything compiles fine, but mapping these objects fails. After some stepping around, I found that when calling map(), this code in Mappable.swift cannot grab the object. It just returns nil.

...

if var object = klass.objectForMapping(map: map) as? N {
    object.mapping(map: map)
    return object
}

Any ideas?

[robbiet480]

static func objectForMapping(map: Map) -> BaseMappable? {
    return Parent()
}

My understanding is that objectForMapping should be inspecting the incoming map and determining what child class the object should be and then returning that class.

[mitchtreece]

@robbiet480 Is that the only way? What if the JSON I'm getting is generic (no "type" property).

[tristanhimmelman]

@mitchtreece the other solution is to override the objectForMapping function in Child:

    override class func objectForMapping(map: Map) -> BaseMappable? {
        return Child()
    }

Note you will have to change static to class.

Your original implementation wasn't working because Mapper was trying to cast the Parent object returned in objectForMapping to a Child. This would always evaluate to nil in this scenario.

[mitchtreece]

@tristanhimmelman Wow I can't believed I missed that. That's exactly what I needed. Thank you 😄

[vincentSuwenliang]

class RegisteredService: Object, StaticMappable {
    dynamic var service_id: Int = 0
    dynamic var client_id: Int = 0
    dynamic var expiry_date: Date?

    class func objectForMapping(map: Map) -> BaseMappable? {
        return TableShared_Time()
    }

    func mapping(map: Map) {

        service_id <- map["service_id"]
        client_id <- map["client_id"]
        expiry_date <- (map["expiry_date"], YMDDateTransform())

    }

}


class TableShared_Time: Object, Mappable {
    dynamic var creation_time: Date?
    dynamic var last_update_time: Date?
    dynamic var visible: Bool = true

    required convenience init?(map: Map) {
        self.init()
    }

    func mapping(map: Map) {
        creation_time <- (map["creation_time"], YMDTimeDateTransform())
        last_update_time <- (map["last_update_time"], YMDTimeDateTransform())
        visible <- (map["visible"], BoolTransform())
    }

}

hi, could you please help me to find out the solution of this error? Use StaticMapple solved the init problem, but can not access the son's property when get response