danilValeev/ObjectMapper operator for Realm.md

## ObjectMapper operator for Realm.md

      
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              ObjectMapper operator for Realm.md
            
          
    This code helps using ObjectMapper with RealmSwift.
RealmSwift uses List<T> collection for "to many" relashionships and RealmOptional<T> for optional primitive types, but ObjectMapper can't map directly to List<T> and RealmOptional<T>.
With this operators you can properly define RealmSwift's relashionships and optional properties and use <- operator to map them.
Example

import Foundation
import RealmSwift
import ObjectMapper

class Chat: Object, Mappable {

    let messages = List<Message>()

    func mapping(map: Map) {
        // use <- operator to map a List
        messages <- map["messages"]
    }

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

class Message: Object, Mappable {

    dynamic var text: String? = nil

    let length = RealmOptional<Int>()

    func mapping(map: Map) {
        text <- map["text"]
        // use <- operator to map a RealmOptional
        length <- map["length"]
    }

    required convenience init?(map: Map) {
        self.init()
    }
    
}
Swift 3

import Foundation
import RealmSwift
import ObjectMapper

infix operator <-

/// Object of Realm's List type
public func <- <T: Mappable>(left: List<T>, right: Map) {
    var array: [T]?

    if right.mappingType == .toJSON {
        array = Array(left)
    }

    array <- right

    if right.mappingType == .fromJSON {
        if let theArray = array {
            left.append(objectsIn: theArray)
        }
    }
}

/// Object of Realm's RealmOptional type
public func <- <T>(left: RealmOptional<T>, right: Map) {
    var optional: T?

    if right.mappingType == .toJSON {
        optional = left.value
    }

    optional <- right

    if right.mappingType == .fromJSON {
        if let theOptional = optional {
            left.value = theOptional
        }
    }
}
Swift 2

infix operator <- {}

/// Object of Realm's List type
public func <- <T: Mappable>(left: List<T>, right: Map) {
    var array: [T]?

    if right.mappingType == .ToJSON {
        array = Array(left)
    }

    array <- right

    if right.mappingType == .FromJSON {
        if let theArray = array {
            left.appendContentsOf(theArray)
        }
    }
}

/// Object of Realm's RealmOptional type
public func <- <T>(left: RealmOptional<T>, right: Map) {
    var optional: T?

    if right.mappingType == .ToJSON {
        optional = left.value
    }

    optional <- right

    if right.mappingType == .FromJSON {
        if let theOptional = optional {
            left.value = theOptional
        }
    }
}