在将名为"localFilePath"的String属性添加到名为GenericAttachment的核心数据实体后，当我们试图映射这些对象的集合时，我们开始遇到异常。
我们的几个实体与GenericAttachment的无序集合有一种称为"附件"的多对多关系。
其中一个实体被称为InspectionMO。GenericAttatchment与InspectionMO有一个多对多的关系"inspection"(而不是"inspections"，oops)。当我们得到InspectionMO的附件并试图映射它们时，我们会得到以下异常：
NSInternalInconsistencyException
I/O error for database at /Users/justingarcia/Library/Developer/CoreSimulator/Devices/D075B44C-4F54-4703-8817-3DC4A6E7314E/data/Containers/Data/Application/F425E5AC-C215-4BE8-93DB-A3E6C48C83C4/Library/Application Support/Procore/Procore. SQLite error code:1, 'no such column: t1.Z_55ATTACHMENTS5'
以下是异常堆栈跟踪：
#0 0x000000010c94f705 in objc_exception_throw ()
#1 0x000000010e928f00 in -[NSSQLiteConnection prepareSQLStatement:] ()
#2 0x000000010ea99305 in -[NSSQLiteConnection selectRowsWithStatement:cached:] ()
#3 0x000000010e941d0b in newFetchedRowsForFetchPlan_MT ()
#4 0x000000010eb6e574 in _newFetchedPKsForRelationshipFaultRequest ()
#5 0x000000010eb6efba in _executeNewValuesForRelationshipFaultRequest ()
#6 0x000000010ead19a2 in -[NSSQLRelationshipFaultRequestContext executeRequestCore:] ()
#7 0x000000010eb40a00 in -[NSSQLStoreRequestContext executeRequestUsingConnection:] ()
#8 0x000000010eb14e5b in __52-[NSSQLDefaultConnectionManager handleStoreRequest:]_block_invoke ()
#9 0x000000011b25f602 in _dispatch_client_callout ()
#10 0x000000011b26d653 in _dispatch_lane_barrier_sync_invoke_and_complete ()
#11 0x000000010eb14d40 in -[NSSQLDefaultConnectionManager handleStoreRequest:] ()
#12 0x000000010eb1cbb4 in -[NSSQLCoreDispatchManager routeStoreRequest:] ()
#13 0x000000010ea61515 in -[NSSQLCore dispatchRequest:withRetries:] ()
#14 0x000000010ea5cdaa in -[NSSQLCore _newValuesForRelationship:forObjectWithID:withContext:error:] ()
#15 0x000000010e97a8cb in -[NSSQLCore newValueForRelationship:forObjectWithID:withContext:error:] ()
#16 0x000000010ea449d9 in __110-[NSPersistentStoreCoordinator(_NSInternalMethods) newValueForRelationship:forObjectWithID:withContext:error:]_block_invoke ()
#17 0x000000010ea39437 in -[NSPersistentStoreCoordinator _routeLightweightBlock:toStore:] ()
#18 0x000000010e97a7f7 in -[NSPersistentStoreCoordinator(_NSInternalMethods) newValueForRelationship:forObjectWithID:withContext:error:] ()
#19 0x000000010ea0b89e in __107-[NSManagedObjectContext(_NestedContextSupport) newValueForRelationship:forObjectWithID:withContext:error:]_block_invoke ()
#20 0x000000010e972108 in internalBlockToNSManagedObjectContextPerform ()
#21 0x000000011b25f602 in _dispatch_client_callout ()
#22 0x000000011b26d653 in _dispatch_lane_barrier_sync_invoke_and_complete ()
#23 0x000000010e972074 in _perform ()
#24 0x000000010e972c37 in -[NSManagedObjectContext(_NestedContextSupport) newValueForRelationship:forObjectWithID:withContext:error:] ()
#25 0x000000010e97a421 in -[NSFaultHandler retainedFulfillAggregateFaultForObject:andRelationship:withContext:] ()
#26 0x000000010e9a621e in -[_NSFaultingMutableSet willReadWithContents:] ()
#27 0x000000010e94e6a6 in -[_NSFaultingMutableSet count] ()
#28 0x000000011a9e9bdd in protocol witness for Collection.count.getter in conformance Set<A> ()
#29 0x000000011a8726d1 in Collection.map<A>(_:) ()
#30 0x00000001162ad07e in ObjectImportHelper.copyToMany<A>(_:to:cache:deleteMissing:onCopy:) at /Users/justingarcia/2/iOS/Procore/Core/Utils/ObjectImportHelper+Relationships.swift:163
…
以下是一些核心数据记录：
CoreData: sql: SELECT 0, t0.Z_PK FROM Z_55INSPECTION t1 JOIN ZGENERICATTACHMENT t0 ON t0.Z_PK = t1.Z_55ATTACHMENTS5 WHERE t1.Z_70INSPECTION = ?
2019-01-25 13:50:17.727987-0800 Procore[34877:10124838] [logging] no such column: t1.Z_55ATTACHMENTS5
CoreData: annotation: Disconnecting from sqlite database due to an error.
2019-01-25 13:50:17.748021-0800 Procore[34877:10124838] [error] error: (1) I/O error for database at /var/mobile/Containers/Data/Application/FFEB392B-302B-479E-98E8-008333FC2714/Library/Application Support/Procore/Procore. SQLite error code:1, 'no such column: t1.Z_55ATTACHMENTS5'
CoreData: error: (1) I/O error for database at /var/mobile/Containers/Data/Application/FFEB392B-302B-479E-98E8-008333FC2714/Library/Application Support/Procore/Procore. SQLite error code:1, 'no such column: t1.Z_55ATTACHMENTS5'
CoreData: annotation: total fetch execution time: 0.0207s for 0 rows.
2019-01-25 13:50:17.748727-0800 Procore[34877:10124838] [error] error: exception during newFetchedPKsForSourceID: I/O error for database at /var/mobile/Containers/Data/Application/FFEB392B-302B-479E-98E8-008333FC2714/Library/Application Support/Procore/Procore. SQLite error code:1, 'no such column: t1.Z_55ATTACHMENTS5' with userInfo of {
NSFilePath = "/var/mobile/Containers/Data/Application/FFEB392B-302B-479E-98E8-008333FC2714/Library/Application Support/Procore/Procore";
NSSQLiteErrorDomain = 1;
}
我们正在使用NSPersistentStoreDescription的shouldMigrateStoreAutomatically和shouldInferMappingModelAutomatically，我在日志中没有看到任何迁移错误(我们正在使用-com.apple.CoreData.MigrationDebug 1)。
我们打开了SQLite数据库文件，发现Z_55INSPECTION表在迁移到这个新版本之前和之后都有一个名为Z_55ATTACHMENTS6(而不是Z_55ATTPACHMENTS5)的列，我们在这个新版本中向GenericAttachment添加了localFilePath属性。
那么，为什么核心数据要寻找一个名为Z_55ATTACHMENTS5而不是Z_55ATTPACHMENTS6的列呢？
我们在谷歌上搜索后发现了这两篇苹果邮件列表文章：一个问题和这个后续文章，我认为是在说，当多个实体与另一个实体有很多同名关系时，就会出现列名末尾的数字。在我们的案例中，我们有几个多对多的关系，称为GenericAttachment的附件。但我们没有添加一个名为附件的新关系，我们只是在GenericAttachment中添加了一个属性。也许如果我们将所有这些关系重命名为唯一的关系，问题就会消失？
它选择该列，因为查询引用Z_55INSPECTION.Z_55ATTACHMENTS5:
SELECT 0, t0.Z_PK FROM Z_55INSPECTION t1
JOIN ZGENERICATTACHMENT t0 ON t0.Z_PK = t1.Z_55ATTACHMENTS5
WHERE t1.Z_70INSPECTION = ?
最简单的方法可能是将该列从Z_55ATTACHMENTS6重命名为Z_55ATTACHMENTS5
保留数据库的备份，以确保没有其他内容引用它。