[Core Data] Make new Core Data migration path. Remove models below 30 (#15987)

Author: iamgabrielma

Modules/Sources/Storage/CoreData/CoreDataIterativeMigrator.swift

@@ -59,6 +59,18 @@ final class CoreDataIterativeMigrator {
         // Find the current model used by the store.
         let sourceModel = try model(for: sourceMetadata)
 
+        // Check if we should nuke the DB entirely based on the oldest supported data model.
+        // We will attempt to either move the merchant to the latest model version, or perform an iterative migration
+        // The persistent store coordinator will automatically create a fresh store with the current model as needed.
+        if shouldDestroyPersistentStore(for: sourceModel) {
+            do {
+                try persistentStoreCoordinator.destroyPersistentStore(at: sourceStoreURL, ofType: storeType, options: nil)
+                DDLogInfo("[CoreDataIterativeMigrator] Database at \(sourceStoreURL) destroyed successfully.")
+            } catch {
+                DDLogError("[CoreDataIterativeMigrator] Database destruction failed. Error: \(error). Falling back to iterative migration.")
+            }
+        }
+
         // Get the steps to perform the migration.
         let steps = try MigrationStep.steps(using: modelsInventory, source: sourceModel, target: targetModel)
         guard !steps.isEmpty else {
@@ -176,4 +188,18 @@ private extension CoreDataIterativeMigrator {
             .appendingPathComponent("migration_\(UUID().uuidString)")
             .appendingPathExtension("sqlite")
     }
+
+    func shouldDestroyPersistentStore(for sourceModel: NSManagedObjectModel) -> Bool {
+        guard let sourceVersion = CoreDataMigratorUtils.findSourceVersion(for: sourceModel, in: modelsInventory) else {
+            // If the model is not found in inventory it's from a deleted model version
+            // The database can be destroyed for a fresh start
+            DDLogInfo("Source model not found in available model versions. Will destroy database for fresh start.")
+            return true
+        }
+
+        // Model found in inventory, so it's a supported version. Use iterative migration
+        DDLogInfo("Source model \(sourceVersion.name) found in available versions. Will use iterative migration.")
+        return false
+    }
+
 }

Modules/Sources/Storage/CoreData/CoreDataManager.swift

@@ -242,7 +242,7 @@ public final class CoreDataManager: StorageManagerType {
     }
 
     /// Migrates the current persistent store to the latest data model if needed.
-    /// - Returns: an array of debug messages for logging. Please feel free to remove when #2371 is resolved.
+    /// - Returns: an array of debug messages for logging.
     private static func migrateDataModelIfNecessary(using coordinator: NSPersistentStoreCoordinator,
                                                     storeURL: URL,
                                                     modelsInventory: ManagedObjectModelsInventory) -> [String] {

Modules/Sources/Storage/CoreData/CoreDataMigratorUtils.swift

@@ -0,0 +1,19 @@
+import CoreData
+
+struct CoreDataMigratorUtils {
+    /// Finds the ModelVersion that corresponds to the given NSManagedObjectModel
+    static func findSourceVersion(for sourceModel: NSManagedObjectModel,
+                                  in modelsInventory: ManagedObjectModelsInventory) -> ManagedObjectModelsInventory.ModelVersion? {
+        do {
+            let allModels = try modelsInventory.models(for: modelsInventory.versions)
+            for (index, model) in allModels.enumerated() {
+                if model.isEqual(sourceModel) {
+                    return modelsInventory.versions[index]
+                }
+            }
+        } catch {
+            DDLogError("[CoreDataMigratorUtils] Error loading models for version detection: \(error)")
+        }
+        return nil
+    }
+}

Modules/Sources/Storage/Model/MIGRATIONS.md

@@ -459,50 +459,50 @@ This file documents changes in the WCiOS Storage data model. Please explain any
 - Delete `OrderStats` entity
 - Delete `OrderStatsItem` entity
 
-## Model 29 (Release 4.7.0.0)
+## Model 29 (Release 4.7.0.0) - Deleted
 - @pmusolino 2020-06-29
 - Add `siteID` attribute to `ProductTag` entity
 - Update `ProductTag`'s  `product` relationship to `products`
 - Update `Product`'s `tags` relationship with `nullify` as delete rule
 - Used mapping model: `WooCommerceModelV28toV29.xcmappingmodel` to remove product tags without `siteID`
 
-## Model 28 (Release 4.5.0.0)
+## Model 28 (Release 4.5.0.0) - Deleted
 - @jaclync 2020-06-05
 - Add `buttonText` attribute to `Product` entity
 
-## Model 27 (Release 3.9.0.1)
+## Model 27 (Release 3.9.0.1) - Deleted
 - @ecarrion 2020-03-30
 - Update `ProductCategory`'s `product` relationship to `products`
 - Add `siteID` and `parentID` to  `ProductCategory` entity 
 - Used mapping model: `WooCommerceModelV26toV27.xcmappingmodel` to remove product categories without `siteID`
 
-## Model 26 (Release 3.5.0.0)
+## Model 26 (Release 3.5.0.0) - Deleted
 - @jaclync 2019-01-14
 - Update `Product`'s `images` relationship to be ordered
 
-## Model 25 (Release 3.4.0.0)
+## Model 25 (Release 3.4.0.0) - Deleted
 - @pmusolino 2019-01-7
 - Add `gmtOffset` attribute to `Site` entity
 
-## Model 24 (Release 3.3.0.0)
+## Model 24 (Release 3.3.0.0) - Deleted
 - @jaclync 2019-12-2
 - New `ProductShippingClass` entity
 - Add `dateOnSaleStart` attribute to `Product` entity
 - Add `dateOnSaleEnd` attribute to `Product` entity
 - New `TaxClass` entity
 
-## Model 23 (Release 3.2.0.0)
+## Model 23 (Release 3.2.0.0) - Deleted
 - @jaclync 2019-11-15
 - New `Attribute` entity
 - New `ProductVariation` entity
 - New `Product.productVariations` relationship
 
-## Model 22 (Release 3.1.0.0)
+## Model 22 (Release 3.1.0.0) - Deleted
 - @pmusolino 2019-11-4
 - New `ShippingLine` entity
 - New `Order.shippingLines` relationship
 
-## Model 21 (Release 2.9.0.0)
+## Model 21 (Release 2.9.0.0) - Deleted
 - @mindgraffiti 2019-10-11
 - New `OrderItemTax` entity
 - New `OrderItemTaxRefund` entity
@@ -512,7 +512,7 @@ This file documents changes in the WCiOS Storage data model. Please explain any
 - New `Refund` entity
 - New `Refund.items` relationship
 
-## Model 20 (Release 2.8.0.0)
+## Model 20 (Release 2.8.0.0) - Deleted
 - @jaclync 2019-09-17
 - New `ProductSearchResults` entity
 - New `Product.searchResults` relationship
@@ -524,7 +524,7 @@ This file documents changes in the WCiOS Storage data model. Please explain any
 - New `OrderRefundCondensed` entity
 - New `Order.refunds` relationship
 
-## Model 19 (Release 2.6.0.0)
+## Model 19 (Release 2.6.0.0) - Deleted
 - @ctarda 2019-08-21
 - Add `ProductReview` entity
 
@@ -534,33 +534,33 @@ This file documents changes in the WCiOS Storage data model. Please explain any
 - @jaclync 2019-08-06
 - Add `timeRange` attribute to `OrderStatsV4` entity
 
-## Model 18 (Release 2.5.0.0)
+## Model 18 (Release 2.5.0.0) - Deleted
 - @ctarda 2019-07-30
     - Add `OrderCount` entity
     - Add `OrderCountItem` entity
 
-## Model 17 (Release 2.3.0.0)
+## Model 17 (Release 2.3.0.0) - Deleted
 - @ctarda 2019-07-10
     - Add `OrderStatsV4` entity
     - Add `OrderStatsV4Totals` entity
     - Add `OrderStatsV4Interval` entity
 
-## Model 16 (Release 2.0.0.0)
+## Model 16 (Release 2.0.0.0) - Deleted
 - @mindgraffiti 2019-05-29
     - Add `ProductDownload` entity
 
-## Model 15 (Release 1.9.0.0)
+## Model 15 (Release 1.9.0.0) - Deleted
 - @mindgraffiti 2019-05-03
     - Delete `ProductVariation` entity
     - Delete `ProductVariationAttribute` entity
     - Delete `ProductVariationDimensions` entity
     - Delete `ProductVariationImage` entity
 
-## Model 14 (Release 1.8.0.0)
+## Model 14 (Release 1.8.0.0) - Deleted
 - @astralbodies 2019-04-22
     - New `AccountSettings` entity with `tracksOptOut` attribute.
 
-## Model 13 (Release 1.6.0.0)
+## Model 13 (Release 1.6.0.0) - Deleted
 - @bummytime 2019-03-28
     - Added `settingGroupKey` attribute on `SiteSetting` entity
 
@@ -570,7 +570,7 @@ This file documents changes in the WCiOS Storage data model. Please explain any
     - New `ProductVariationDimensions` entity
     - New `ProductVariationImage` entity
 
-## Model 12 (Release 1.5.0.0)
+## Model 12 (Release 1.5.0.0) - Deleted
 - @bummytime 2019-03-20
     - New `Product` entity
     - New `ProductDefaultAttribute` entity
@@ -583,13 +583,13 @@ This file documents changes in the WCiOS Storage data model. Please explain any
 - @ctarda 2019-03-14
     - Adds `ShipmentTrackingProvider` and `ShipmentTrackingProviderGroup`
 
-## Model 11 (Release 1.4.0.0)
+## Model 11 (Release 1.4.0.0) - Deleted
 
 - @mindgraffiti  2019-02-27
     - Adds  `siteID` and `total` attributes to `OrderStatus` 
     - Changes `name` and `total` on `OrderStatus` to be optional
 
-## Model 10 (Release 1.3.0.0)
+## Model 10 (Release 1.3.0.0) - Deleted
 Used mapping model: `WooCommerceModelV9toV10.xcmappingmodel`
 
 - @astralbodies 2019-02-08
@@ -602,29 +602,29 @@ Used mapping model: `WooCommerceModelV9toV10.xcmappingmodel`
     - Changes `status` attribute on `Order` to `statusKey`
     - New `OrderStatus` entity
 
-## Model 9 (Release 1.0.0.1) 
+## Model 9 (Release 1.0.0.1) - Deleted
 - @bummytime 2019-01-11
     - Added `price` attribute on `OrderItem` entity
 
 Note: the 1.0.0 model 9 never made it to our users so we are not reving the version #.
 
-## Model 9 (Release 1.0.0)
+## Model 9 (Release 1.0.0) - Deleted
 - @jleandroperez 2018-12-26
     - New `Order.exclusiveForSearch` property
     - New `OrderSearchResults` entity
 
-## Model 8 (Release 0.13)
+## Model 8 (Release 0.13) - Deleted
 - @jleandroperez 2018-12-14
     - Removed  `Site.isJetpackInstalled` attribute.
 
 - @bummytime 2018-12-11
     - New `OrderNote.author` attribute
 
-## Model 7
+## Model 7 - Deleted
 - @bummytime 2018-11-26
     - New `Note.deleteInProgress` property
 
-## Model 6
+## Model 6 - Deleted
 - @jleandroperez 2018-11-15
     - New `Note.siteID` property
 
@@ -635,26 +635,26 @@ Note: the 1.0.0 model 9 never made it to our users so we are not reving the vers
     - Added new attribute: `isJetpackInstalled`, to site entity
     - Added new attribute: `plan`, to site entity
 
-## Model 5
+## Model 5 - Deleted
 - @bummytime 2018-10-26
     - Added new entity: `Note`, to encapsulate all things notifications
 
 - @bummytime 2018-10-23
     - Added new entity: `SiteSetting`, to encapsulate all of the site settings
 
-## Model 4
+## Model 4 - Deleted
 - @bummytime 2018-10-09
     - Added new entity: `SiteVisitStats`, to encapsulate all of the visitor stats for a given site & granularity
     - Added new entity: `SiteVisitStatsItem`, to encapsulate all the visitor stats for a specific period
     - Added new entity: `OrderStats`, to encapsulate all of the order stats for a given site & granularity
     - Added new entity: `OrderStatsItem`, to encapsulate all the order stats for a specific period
 
-## Model 3
+## Model 3 - Deleted
 - @bummytime 2018-09-19
     - Widened `quantity` attribute on `OrderItem` from Int16 to Int64
     - Widened `quantity` attribute on `TopEarnerStatsItem` from Int16 to Int64
 
-## Model 2
+## Model 2 - Deleted
 - @bummytime 2018-09-05
     - Added new entity: `TopEarnerStats`, to encapsulate all of the top earner stats for a given site & granularity
     - Added new entity: `TopEarnerStatsItem`, to encapsulate all the top earner stats for a specific product