Migration (#16)

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+### 1.1.0
+- Added migration between model versions.
+- Refinements.
+
 ### 1.0.0
 
 - Refinements.

README.md

@@ -53,7 +53,7 @@ platform :ios, '10.0'
 use_frameworks!
 
 target '<Your Target Name>' do
-    pod 'CoreDataPlus', '~> 1.0.0'
+    pod 'CoreDataPlus', '~> 1.1.0'
 end
 ```
 
@@ -77,7 +77,7 @@ $ brew install carthage
 To integrate CoreDataPlus into your Xcode project using Carthage, specify it in your `Cartfile`:
 
 ```ogdl
-github "tinrobots/CoreDataPlus" ~> 1.0.0
+github "tinrobots/CoreDataPlus" ~> 1.1.0
 ```
 
 Run `carthage update` to build the framework and drag the built `CoreDataPlus.framework` into your Xcode project.
@@ -89,7 +89,7 @@ Once you have your Swift package set up, adding CoreDataPlus as a dependency is
 
 ```swift
 dependencies: [
-    .package(url: "https://github.com/tinrobots/CoreDataPlus.git", from: "1.0.0")
+    .package(url: "https://github.com/tinrobots/CoreDataPlus.git", from: "1.1.0")
 ]
 ```
 

Sources/CoreDataPlusError.swift

@@ -41,13 +41,14 @@ public enum CoreDataPlusError: Error {
   case fetchFailed(error: Error)
   case persistentStoreCoordinatorNotFound(context: NSManagedObjectContext)
   case saveFailed(error: Error)
+  case migrationFailed(error: Error)
 
   /// **CoreDataPlus**
   ///
   /// The `Error` returned by a system framework associated with a CoreDataPlus failure error.
   public var underlyingError: Error? {
     switch self {
-    case .fetchFailed(let error), .saveFailed(let error):
+    case .executionFailed(let error), .fetchFailed(let error), .saveFailed(let error), .migrationFailed(error: let error):
       return error
     default:
       return nil
@@ -72,13 +73,16 @@ extension CoreDataPlusError: LocalizedError {
       return "Returned multiple objects, expected max 1."
 
     case .fetchFailed(let error):
-      return "The fetch could not be completed because of error:\n\(error.localizedDescription)"
+      return "The fetch could not be completed because of error:\n\(error)"
 
     case .persistentStoreCoordinatorNotFound(let context):
       return "\(context.description) doesn't have a NSPersistentStoreCoordinator."
 
     case .saveFailed(let error):
-      return "The save operation could not be completed because of error:\n\(error.localizedDescription)"
+      return "The save operation could not be completed because of error:\n\(error)"
+
+    case .migrationFailed(error: let error):
+      return "The migration could not be completed because of error:\n\(error)"
     }
   }
 

Sources/Migration/Migration.swift

@@ -0,0 +1,121 @@
+//
+// CoreDataPlus
+//
+// Copyright © 2016-2018 Tinrobots.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+// https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/CoreDataVersioning/Articles/vmLightweightMigration.html
+// https://developer.apple.com/documentation/coredata/heavyweight_migration
+// https://www.objc.io/issues/4-core-data/core-data-migration/
+
+import CoreData
+
+public struct Migration {
+
+  private init() { }
+
+  /// **CoreDataPlus**
+  ///
+  /// Migrates a store to a given version.
+  ///
+  /// - Parameters:
+  ///   - sourceURL: the current store URL.
+  ///   - targetVersion: the ModelVersion to which the store is needed to migrate to.
+  ///   - progress: a Progress instance to monitor the migration.
+  /// - Throws: It throws an error in cases of failure.
+  public static func migrateStore<Version: ModelVersion>(at sourceURL: URL, targetVersion: Version, progress: Progress? = nil) throws {
+    try migrateStore(from: sourceURL, to: sourceURL, targetVersion: targetVersion, deleteSource: false, progress: progress)
+  }
+
+  /// **CoreDataPlus**
+  ///
+  /// Migrates a store to a given version.
+  ///
+  /// - Parameters:
+  ///   - sourceURL: the current store URL.
+  ///   - targetURL: the store URL after the migration phase.
+  ///   - targetVersion: the ModelVersion to which the store is needed to migrate to.
+  ///   - deleteSource: if `true` the initial store will be deleted after the migration phase.
+  ///   - progress: a Progress instance to monitor the migration.
+  /// - Throws: It throws an error in cases of failure.
+  public static func migrateStore<Version: ModelVersion>(from sourceURL: URL, to targetURL: URL, targetVersion: Version, deleteSource: Bool = false, progress: Progress? = nil) throws {
+    guard let sourceVersion = Version(persistentStoreURL: sourceURL as URL) else {
+      fatalError("A ModelVersion for the store at URL \(sourceURL) could not be found.")
+    }
+
+    do {
+      guard try sourceVersion.isMigrationPossible(for: sourceURL, to: targetVersion) else {
+        return
+      }
+
+      var currentURL = sourceURL
+      let steps = sourceVersion.migrationSteps(to: targetVersion)
+
+      guard steps.count > 0 else {
+        return
+      }
+
+      var migrationProgress: Progress?
+
+      if let progress = progress {
+        migrationProgress = Progress(totalUnitCount: Int64(steps.count), parent: progress, pendingUnitCount: progress.totalUnitCount)
+      }
+
+      for step in steps {
+        try autoreleasepool {
+          migrationProgress?.becomeCurrent(withPendingUnitCount: 1)
+          let manager = NSMigrationManager(sourceModel: step.sourceModel, destinationModel: step.destinationModel)
+          migrationProgress?.resignCurrent()
+
+          let destinationURL = URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true).appendingPathComponent(UUID().uuidString)
+
+          for mapping in step.mappings {
+            try manager.migrateStore(from: currentURL,
+                                     sourceType: NSSQLiteStoreType,
+                                     options: nil,
+                                     with: mapping,
+                                     toDestinationURL: destinationURL,
+                                     destinationType: NSSQLiteStoreType,
+                                     destinationOptions: nil)
+          }
+
+          if currentURL != sourceURL {
+            try NSPersistentStoreCoordinator.destroyStore(at: currentURL)
+          }
+          currentURL = destinationURL
+        }
+      }
+
+      try NSPersistentStoreCoordinator.replaceStore(at: targetURL, withStoreAt: currentURL)
+
+      if currentURL != sourceURL {
+        try NSPersistentStoreCoordinator.destroyStore(at: currentURL)
+      }
+
+      if targetURL != sourceURL && deleteSource {
+        try NSPersistentStoreCoordinator.destroyStore(at: sourceURL)
+      }
+
+    } catch {
+      throw CoreDataPlusError.migrationFailed(error: error)
+    }
+
+  }
+
+}

Sources/Migration/MigrationSep.swift

@@ -0,0 +1,39 @@
+//
+// CoreDataPlus
+//
+// Copyright © 2016-2018 Tinrobots.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+import CoreData
+
+/// **CoreDataPlus**
+///
+/// Represents a single step during the migration process.
+public final class MigrationStep {
+  var sourceModel: NSManagedObjectModel
+  var destinationModel: NSManagedObjectModel
+  var mappings: [NSMappingModel]
+
+  init(source: NSManagedObjectModel, destination: NSManagedObjectModel, mappings: [NSMappingModel]) {
+    self.sourceModel = source
+    self.destinationModel = destination
+    self.mappings = mappings
+  }
+}