如何將相關對象從CoreData中的一個對象移動到另一個對象

我遇到了CoreData中的一些數據庫操作問題。有時候，視圖會在流程中間刷新並顯示錯誤的狀態。有時數據甚至丟失。如何將相關對象從CoreData中的一個對象移動到另一個對象

我有以下CoreData對象模型：

課程有很多學生

現在我想合併兩個療程A和B在一起，這樣以後所有課程B的學生應該被分配到課程一併且課程B不再存在。

（A學生在正好一個療程）

目前我正在做這種方式，其工作的大部分時間，但有那樣的問題：

Course courseA = [self someCourse]; 
Course courseB = [self someOtherCourse]; 

for (Student *student in courseB.students) { 
    student.course = courseA; 
} 

[managedObjectContext deleteObject:courseB]; 

NSError *error = nil; 
[managedObjectContext save:&error]; 
if(error != nil) { 
    NSLog(@"Deletion of Course failed."); 
}

有時我得到以下錯誤的設備日誌：

Core Data: warning: validation recovery attempt FAILED with Error Domain=NSCocoaErrorDomain Code=1550 "The operation couldn’t be completed. (Cocoa error 1550.)" UserInfo=0x1d97f8e0 {NSLocalizedDescription=The operation couldn’t be completed. (Cocoa error 1550.), Dangling reference to an invalid object.=null, NSValidationErrorObject=<Course: 0x1cad56c0> (entity: Course; id: 0x1ca69380 <x-coredata:///Course/tA8FBABB4-2BBD-4A5D-ADFA-94D6F08F6A6D3519> ; data: { 
    endDateTime = "2014-09-18 17:38:17 +0000"; 
    place = "0x1db4c120 <x-coredata:///Place/tA8FBABB4-2BBD-4A5D-ADFA-94D6F08F6A6D7394>"; 
    room = "0x18d696a0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Room/p1>"; 
    category = "0x18e8f990 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/CDCategory/p1>"; 
    changed = "2014-09-19 08:04:03 +0000"; 
    startDateTime = "2014-09-18 17:30:01 +0000"; 
    syncInfos = "<relationship fault: 0x1cbb5bb0 'syncInfos'>"; 
    students =  (
     "0x18d073c0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461393>", 
     "0x1c911b00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461383>", 
     "0x1c915770 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461401>", 
     "0x1a0a6560 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461387>", 
     "0x1c90e2f0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461346>", 
     "0x1cd7fc00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461370>", 
     "0x1a0bdbf0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461374>", 
     "0x1cb11090 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461395>", 
     "0x1cf31fc0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461379>", 
     "0x1cda6230 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461339>", 
     "(...and 133 more...)" 
    ); 
}), NSAffectedObjectsErrorKey=(
    "<Student: 0x1cf6c000> (entity: Student; id: 0x1a36fc70 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461431> ; data: <fault>)" 
), NSValidationErrorKey=students, NSValidationErrorValue=Relationship 'students' on managed object (0x1cad56c0) <Course: 0x1cad56c0> (entity: Course; id: 0x1ca69380 <x-coredata:///Course/tA8FBABB4-2BBD-4A5D-ADFA-94D6F08F6A6D3519> ; data: { 
    endDateTime = "2014-09-18 17:38:17 +0000"; 
    place = "0x1db4c120 <x-coredata:///Place/tA8FBABB4-2BBD-4A5D-ADFA-94D6F08F6A6D7394>"; 
    room = "0x18d696a0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Room/p1>"; 
    category = "0x18e8f990 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/CDCategory/p1>"; 
    changed = "2014-09-19 08:04:03 +0000"; 
    startDateTime = "2014-09-18 17:30:01 +0000"; 
    syncInfos = "<relationship fault: 0x1cbb5bb0 'syncInfos'>"; 
    students =  (
     "0x18d073c0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461393>", 
     "0x1c911b00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461383>", 
     "0x1c915770 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461401>", 
     "0x1a0a6560 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461387>", 
     "0x1c90e2f0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461346>", 
     "0x1cd7fc00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461370>", 
     "0x1a0bdbf0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461374>", 
     "0x1cb11090 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461395>", 
     "0x1cf31fc0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461379>", 
     "0x1cda6230 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461339>", 
     "(...and 133 more...)" 
    ); 
}) with objects {(
    <Student: 0x1d9e48d0> (entity: Student; id: 0x18d073c0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461393> ; data: <fault>), 
    <Student: 0x1ddc6920> (entity: Student; id: 0x1c911b00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461383> ; data: <fault>), 
    <Student: 0x1d991750> (entity: Student; id: 0x1c915770 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461455> ; data: <fault>), 
    <Student: 0x1cf6c000> (entity: Student; id: 0x1a36fc70 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461431> ; data: <fault>) 
)}, NSValidationErrorShouldAttemptRecoveryKey=true} and { 
    "Dangling reference to an invalid object." = "<null>"; 
    NSAffectedObjectsErrorKey =  (
     "<Student: 0x1cf6c000> (entity: Student; id: 0x1a36fc70 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461431> ; data: <fault>)" 
    ); 
    NSLocalizedDescription = "The operation couldn\U2019t be completed. (Cocoa error 1550.)"; 
    NSValidationErrorKey = students; 
    NSValidationErrorObject = "<Course: 0x1cad56c0> (entity: Course; id: 0x1ca69380 <x-coredata:///Course/tA8FBABB4-2BBD-4A5D-ADFA-94D6F08F6A6D3519> ; data: {\n endDateTime = \"2014-09-18 17:38:17 +0000\";\n place = \"0x1db4c120 <x-coredata:///Place/tA8FBABB4-2BBD-4A5D-ADFA-94D6F08F6A6D7394>\";\n room = \"0x18d696a0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Room/p1>\";\n category = \"0x18e8f990 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/CDCategory/p1>\";\n changed = \"2014-09-19 08:04:03 +0000\";\n startDateTime = \"2014-09-18 17:30:01 +0000\";\n points = 1436;\n done = 1;\n notes = \"\";\n syncInfos = \"<relationship fault: 0x1cbb5bb0 'syncInfos'>\";\n students =  (\n  \"0x18d073c0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461393>\",\n  \"0x1c911b00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461383>\",\n  \"0x1c915770 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461401>\",\n  \"0x1a0a6560 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461387>\",\n  \"0x1c90e2f0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461346>\",\n  \"0x1cd7fc00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461370>\",\n  \"0x1a0bdbf0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461374>\",\n  \"0x1cb11090 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461395>\",\n  \"0x1cf31fc0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461379>\",\n  \"0x1cda6230 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461339>\",\n  \"(...and 133 more...)\"\n );\n})"; 
    NSValidationErrorShouldAttemptRecoveryKey = 1; 
    NSValidationErrorValue = "Relationship 'students' on managed object (0x1cad56c0) <Course: 0x1cad56c0> (entity: Course; id: 0x1ca69380 <x-coredata:///Course/tA8FBABB4-2BBD-4A5D-ADFA-94D6F08F6A6D3519> ; data: {\n endDateTime = \"2014-09-18 17:38:17 +0000\";\n place = \"0x1db4c120 <x-coredata:///Place/tA8FBABB4-2BBD-4A5D-ADFA-94D6F08F6A6D7394>\";\n room = \"0x18d696a0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Room/p1>\";\n category = \"0x18e8f990 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/CDCategory/p1>\";\n changed = \"2014-09-19 08:04:03 +0000\";\n startDateTime = \"2014-09-18 17:30:01 +0000\";\n points = 1436;\n done = 1;\n notes = \"\";\n syncInfos = \"<relationship fault: 0x1cbb5bb0 'syncInfos'>\";\n students =  (\n  \"0x18d073c0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461393>\",\n  \"0x1c911b00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461383>\",\n  \"0x1c915770 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461401>\",\n  \"0x1a0a6560 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461387>\",\n  \"0x1c90e2f0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461346>\",\n  \"0x1cd7fc00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461370>\",\n  \"0x1a0bdbf0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461374>\",\n  \"0x1cb11090 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461395>\",\n  \"0x1cf31fc0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461379>\",\n  \"0x1cda6230 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461339>\",\n  \"(...and 133 more...)\"\n );\n}) with objects {(\n <Student: 0x1d9e48d0> (entity: Student; id: 0x18d073c0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461393> ; data: <fault>),\n <Student: 0x1ddc6920> (entity: Student; id: 0x1c911b00 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461383> ; data: <fault>),\n <Student: 0x1d991750> (entity: Student; id: 0x1c915770 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461433> ; data: <fault>),\n <Student: 0x1dbb38f0> (entity: Student; id: 0x1c920ba0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461435> ; data: <fault>),\n <Student: 0x1cf7b780> (entity: Student; id: 0x1c9298f0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461436> ; data: <fault>),\n <Student: 0x1dd3f4f0> (entity: Student; id: 0x1a09a3b0 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461454> ; data: <fault>),\n <Student: 0x1d9e4850> (entity: Student; id: 0x1cbbe040 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461455> ; data: <fault>),\n <Student: 0x1cf6c000> (entity: Student; id: 0x1a36fc70 <x-coredata://16CBD0F6-B399-4A9C-BD51-5EC98BD99EFC/Student/p461431> ; data: <fault>)\n)}"; 
}.

來源

2014-09-19 Thomas Einwaller

如果問題只occures，當在處理變化的觀點重新加載，那麼你必須緩存數據和同步y中的選項我們的讀寫步驟和/或僅在穩定狀態下刷新視圖（所以遷移方法在完成時發送通知）。

如果它也在其他狀態發生，您應該檢查模型中的選項（同步，驗證，刪除規則）或嘗試先保存已遷移的學生然後再刪除。

如果仍然無法正常工作，您能否提供模型和關係的截圖？

順便說一句，爲什麼迭代每一個用戶，而不是使用

[courseB addStudents:courseA.students];

？當然，前提是你有CoreDataGeneratedAccessors這將是你的情況：

@interface Course (CoreDataGeneratedAccessors) 

- (void)addStudentsObject:(Student *)value; 
- (void)removeStudentsObject:(Student *)value; 
- (void)addStudents:(NSSet *)value; 
- (void)removeStudents:(NSSet *)value; 

@end

來源

2014-09-19 09:51:26 geo

我不得不迭代他們因爲這個：http://stackoverflow.com/questions/7385439/exception-thrown-in-nsorderedset-generated-accessors – 2014-09-19 09:58:26

你在Student.course（你們的關係定義有什麼樣刪除規則的可能：「不採取行動」我認爲它應該是「Nullify」）。對無效對象的懸掛引用通常與技術上設置不正確的關係有關。也只是爲了確保我會添加：courseB.students。 在for循環中複製。

來源

2014-09-19 10:01:41

謝謝，Student.course刪除規則「Nullify」和Course.students有刪除規則Cascade，使用副本迭代是一個很好的tipp，將添加 – 2014-09-19 10:35:08

如何將相關對象從CoreData中的一個對象移動到另一個對象

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