Swift で Firebase Database を安全に使う便利なやつたち. README.md にちょっと説明書いた.

README.md

Firebase Datbase の難しい & 嫌なところ

• Database.database().reference() が長い
• Database.database().reference().child("hoge").child(uid") って Query を作るのに間違いが発生しやすい
• そのオブジェクト Readonly なの？ それとも Read, Write なの？
  • firebase database の Rule によって出来る操作が違う
• snapshot.value が Any だから辛い
• snapshot.value のパース処理を書くのがだるい
• 全体的に型がないから辛い

良くした

• Query を作るところを隠蔽した -> Query だけ作ってテストできる
• モデルの型が Unboxable に適合していれば snapshot.value のパース処理の実装が不要
  • SwiftFirebase.swift の public extension FirebaseModelRef where Model: Unboxable など
• モデルの型に適合させる protocol によって Readonly や Read, Write な操作だけに出来る -> Rule をコードに反映できる
  • SystemStatus は Readonly, Configs は Read, Write

Config.swift

//
//  Config.swift
//  SwiftFirebase
//
//  Created by mironal on 2017/05/27.
//  Copyright © 2017年 covelline. All rights reserved.
//

import Foundation
import Unbox
import FirebaseDatabase.FIRDatabaseQuery

/*
 
 readwrite なモデル.
 
 {
   "configs": { <- 全体を取得したいときは ConfigsRef を使って参照. この参照で childByAutoId() を使った書き込みもできる.
     "uid": { <- 特定の uid の Config を取得したいときは ConfigRef を使って参照. この参照で書き込みもできる.
       "canSomething": <boolean>
     },
     "uid": {
       "canSomething": <boolean>
     }
   }
 }

 */
struct Config {
    let canSomething: Bool
}

extension Config: Unboxable {

    init(unboxer: Unboxer) throws {
        canSomething = try unboxer.unbox(key: "canSomething")
    }
}

extension Config: FirebaseModel {}
extension Config: FirebaseStorable {
    func firebaseValue() -> [AnyHashable : Any] {
        return ["canSomething": canSomething]
    }
}

/// "configs/{uid}" への参照
struct ConfigRef {
    let uid: String
}

extension ConfigRef: FirebaseModelRef {
    typealias Model = Config

    var query: DatabaseQuery {
        return rootRef.child("configs").child(uid)
    }
}

extension ConfigRef: FirebaseCreatableValueRef {}
extension ConfigRef: FirebaseRemovableValueRef {}

/// "configs" への参照
struct ConfigsRef {}

extension ConfigsRef: FirebaseArrayModelRef {
    typealias Model = Config

    var query: DatabaseQuery {
        return rootRef.child("configs")
    }
}

extension ConfigsRef: FirebaseChildCreatableValueRef {}

struct OrderedConfigsRef: FirebaseArrayModelRef {
    typealias Model = Config

    var query: DatabaseQuery {
        return rootRef.child("configs").queryOrderedByKey()
    }
}

SwiftFirebase.swift

//
//  SwiftFirebase.swift
//  SwiftFirebase
//
//  Created by mironal on 2017/05/27.
//  Copyright © 2017年 covelline. All rights reserved.
//

import Foundation

import FirebaseDatabase
import Unbox

/// firebase に保存可能であることを示す
public protocol FirebaseStorable {
    func firebaseValue() -> [AnyHashable: Any]
}

/// Firebase Database のモデル
public protocol FirebaseModel {}

/// Firebase Database のモデルへの参照
public protocol FirebaseRef {

    /// この参照が示すモデルの型
    associatedtype Model: FirebaseModel

    /// Database.database().reference() の alias
    var rootRef: DatabaseReference { get }

    /// この参照への query
    var query: DatabaseQuery { get }
}

public extension FirebaseRef {
    var rootRef: DatabaseReference {
        return Database.database().reference()
    }
}

/// このモデルへの参照が値を作成可能であることを示す
/// 対象となるオブジェクトが既に FirebaseModelRef に適合している場合はデフォルトの実装が存在する
public protocol FirebaseCreatableValueRef: FirebaseRef {

    associatedtype Model: FirebaseStorable

    /// firebase の setValue(_ value: Any?, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)
    func setValue(_ value: Model, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)

    /// firebase の setValue(_ value: Any?, andPriority priority: Any?, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)
    func setValue(_ value: Model, andPriority priority: Any?, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)

    /// firebase の updateChildValues(_ values: [AnyHashable : Any], withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)
    func updateChildValues(_ values: Model, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)
}

/// このモデルへの参照が childByAutoId を使用した値を作成可能であることを示す
/// 対象となるオブジェクトが既に FirebaseArrayModelRef に適合している場合はデフォルトの実装が存在する
public protocol FirebaseChildCreatableValueRef: FirebaseRef {

    associatedtype Model: FirebaseStorable

    /// childByAutoId で value を作る
    func setChildValue(_ value: Model, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)

    /// firebase の func setValue(_ value: Any?, andPriority priority: Any?, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)
    func setChildValue(_ value: Model, andPriority priority: Any?, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)
}

/// このモデルへの参照が値を削除可能であることを示す
/// 対象となるオブジェクトが既に FirebaseModelRef に適合している場合はデフォルトの実装が存在する
public protocol FirebaseRemovableValueRef: FirebaseRef {

    /// firebase の　removeValue(completionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)
    func removeValue(completionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void)
}

/// モデル単体への参照
public protocol FirebaseModelRef: FirebaseRef {

    /// firebase の observeSingleEvent(of eventType: DataEventType, with block: @escaping (DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)? = nil)
    func observeSingleEvent(of eventType: DataEventType, with block: @escaping (Model, DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)?)

    /// firebase の observe(_ eventType: DataEventType, with block: @escaping (DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)? = nil) -> UInt
    func observe(_ eventType: DataEventType, with block: @escaping (Model, DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)?) -> UInt
}

/// モデル単体集合への参照
public protocol FirebaseArrayModelRef: FirebaseRef {

    /// firebase の observeSingleEvent(of eventType: DataEventType, with block: @escaping (DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)? = nil)
    func observeSingleEvent(of eventType: DataEventType, with block: @escaping ([String: Model], DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)?)

    /// firebase の observe(_ eventType: DataEventType, with block: @escaping (DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)? = nil) -> UInt
    func observe(_ eventType: DataEventType, with block: @escaping ([String: Model], DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)?) -> UInt
}

enum SwiftFirebaseError: Error {
    case paseError
}

// MARK - 便利なデフォルト実装達

public extension FirebaseModelRef where Model: Unboxable {

    func observeSingleEvent(of eventType: DataEventType, with block: @escaping (Model, DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)?) {

        query.observeSingleEvent(of: eventType, with: { snapshot in
            parse(snapshot: snapshot, block, withCancel: cancelBlock)
        }, withCancel: cancelBlock)
    }

    func observe(_ eventType: DataEventType, with block: @escaping (Model, DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)?) -> UInt {

        return query.observe(eventType, with: { snapshot in
            parse(snapshot: snapshot, block, withCancel: cancelBlock)
        }, withCancel: cancelBlock)
    }
}

public extension FirebaseArrayModelRef where Model: Unboxable {

    func observeSingleEvent(of eventType: DataEventType, with block: @escaping ([String: Model], DataSnapshot) -> Swift.Void, withCancel
        cancelBlock: ((Error) -> Swift.Void)? = nil) {

        query.observeSingleEvent(of: eventType, with: { snapshot in
            parse(snapshot: snapshot, block, withCancel: cancelBlock)
        }, withCancel: cancelBlock)
    }

    func observe(_ eventType: DataEventType, with block: @escaping ([String: Model], DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)?) -> UInt {

        return query.observe(eventType, with: { snapshot in
            parse(snapshot: snapshot, block, withCancel: cancelBlock)
        }, withCancel: cancelBlock)
    }
}

private func parse<Model: Unboxable>(snapshot: DataSnapshot, _ block: @escaping (Model, DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)?) {
    if let dictionary = snapshot.value as? [String: AnyObject], let model: Model = try? unbox(dictionary: dictionary) {
        block(model, snapshot)
    } else {
        print("Parse error \(Model.self)")
        cancelBlock?(SwiftFirebaseError.paseError)
    }
}

private func parse<Model: Unboxable>(snapshot: DataSnapshot, _ block: @escaping ([String: Model], DataSnapshot) -> Swift.Void, withCancel cancelBlock: ((Error) -> Swift.Void)?) {

    var error: SwiftFirebaseError?
    let models: [String: Model] = snapshot.children.reduce([:], { (result, child) -> [String: Model] in

        var result = result
        if let child = child as? DataSnapshot,
            let dict = child.value as? [String: Any],
            let model: Model = try? unbox(dictionary: dict) {

            result[child.key] = model
        } else {
            error = SwiftFirebaseError.paseError
            print("Parse error \(Model.self)")
        }
        return result
    })

    if let error = error {
        cancelBlock?(error)
    } else {
        block(models, snapshot)
    }
}

public extension FirebaseChildCreatableValueRef where Self: FirebaseArrayModelRef {

    var childRef: DatabaseReference {
        return query.ref.childByAutoId()
    }

    func setChildValue(_ value: Model, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void) {
        childRef.setValue(value.firebaseValue(), withCompletionBlock: block)
    }

    func setChildValue(_ value: Model, andPriority priority: Any?, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void) {
        childRef.setValue(value.firebaseValue(), andPriority: priority, withCompletionBlock: block)
    }
}

public extension FirebaseCreatableValueRef where Self: FirebaseModelRef {

    func setValue(_ value: Model, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void) {
        query.ref.setValue(value.firebaseValue(), withCompletionBlock: block)
    }

    func setValue(_ value: Model, andPriority priority: Any?, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void) {
        query.ref.setValue(value.firebaseValue(), andPriority: priority, withCompletionBlock: block)
    }

    func updateChildValues(_ values: Model, withCompletionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void) {
        query.ref.updateChildValues(values.firebaseValue(), withCompletionBlock: block)
    }
}

public extension FirebaseRemovableValueRef where Self: FirebaseModelRef {
    func removeValue(completionBlock block: @escaping (Error?, DatabaseReference) -> Swift.Void) {
        query.ref.removeValue(completionBlock: block)
    }
}

SystemStatus.swift

//
//  SystemStatus.swift
//  SwiftFirebase
//
//  Created by mironal on 2017/05/27.
//  Copyright © 2017年 covelline. All rights reserved.
//

import Foundation
import Unbox
import FirebaseDatabase.FIRDatabaseQuery

/*
 
 readonly なモデル.
 ## model

 {
   "systemStatus": {
     "good": <boolean>
   }
 }
 
 ## rule

 {
   "rules": {
     ".read": "false,
     ".write": "false"
      "systemStatus": {
        ".read: "auth != nil"
      }
    }
 }

 */
struct SystemStatus {
    let good: Bool
}
extension SystemStatus: FirebaseModel {}

extension SystemStatus: Unboxable {
    init(unboxer: Unboxer) throws {
        good = try unboxer.unbox(key: "good")
    }
}

struct SystemStatusRef {}

extension SystemStatusRef: FirebaseModelRef {
    var query: DatabaseQuery {
        return rootRef.child("systemStatus")
    }

    typealias Model = SystemStatus
}

ViewController.swift

//
//  ViewController.swift
//  SwiftFirebaseDemo
//
//  Created by mironal on 2017/05/27.
//  Copyright © 2017年 covelline. All rights reserved.
//

import UIKit

import FirebaseDatabase

class ViewController: UIViewController {

    @IBAction func pushConfig(_ sender: Any) {
        // Database.database().reference().child("configs").child("1").observeSingleEvent(of: ... & パース処理) が以下の1行で書ける
        ConfigRef(uid: "1").observeSingleEvent(of: .value, with: { (config, snapshot) in
            print(config)
        }) { error in
            print(error)
        }
    }

    @IBAction func pushConfigs(_ sender: Any) {

        ConfigsRef().observeSingleEvent(of: .value, with: { (configs, snapshot) in
            print(configs)
        }) { error in
            print(error)
        }
    }
    @IBAction func pushOrderdConfigs(_ sender: Any) {
        OrderedConfigsRef().observeSingleEvent(of: .value, with: { (configs, snapshot) in
            print(configs)
        }) { error in
            print(error)
        }
    }

    @IBAction func pushCreateAutoId(_ sender: Any) {

        let config = Config(canSomething: true)

        ConfigsRef().setChildValue(config) { (error, reference) in

        }
    }

    @IBAction func pushCreateSpecificId(_ sender: Any) {

        let config = Config(canSomething: true)

        ConfigRef(uid: "1").setValue(config) { (error, reference) in

        }
    }

    @IBAction func pushRemoveConfig(_ sender: Any) {
        ConfigRef(uid: "1").removeValue { (error, reference) in
            
        }
    }

}