Grails：如何堅持主細節關係

Question

我已經建立了一個用戶界面，允許您在同一個表單上輸入主記錄（VocabularyTest）和一組詳細記錄（VocabQuestion）。我很高興的是，正被提交的數據是正確的，但是當我試圖保存主記錄，我得到以下錯誤

null id in vocabularytest.VocabQuestion entry 

編輯 - 完整的堆棧跟蹤是

null id in vocabularytest.VocabQuestion entry (don't flush the Session after an exception occurs). Stacktrace follows: 
Message: null id in vocabularytest.VocabQuestion entry (don't flush the Session after an exception occurs) 
    Line | Method 
->> 24 | save  in vocabularytest.VocabularyController 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
| 195 | doFilter in grails.plugin.cache.web.filter.PageFragmentCachingFilter 
|  63 | doFilter in grails.plugin.cache.web.filter.AbstractFilter 
| 1110 | runWorker in java.util.concurrent.ThreadPoolExecutor 
| 603 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^ 722 | run  in java.lang.Thread 

END編輯

我假設這是因爲我的詳細記錄上的外鍵引用爲空，這不會讓我感到意外，因爲我沒有做任何設置。

是被我的控制器接收到的PARAMS如下

title: Dave New Test 
testItems[0].question: Q1 
testItems[0].answer: A1 
testItems[1].question: Q2 
testItems[1].answer: A2 
testItems[2].question: Q3 
testItems[2].answer: A3 
create: Create 

我的域對象是

class VocabularyTest { 

    static hasMany = [testItems: VocabQuestion] 
    static constraints = { 
    } 

    String title; 
    List <VocabQuestion>testItems = LazyList.decorate(
             new ArrayList(), 
             FactoryUtils.instantiateFactory(VocabQuestion.class)); 

} 
class VocabQuestion { 

    static constraints = { 

    } 
    String question 
    String answer 
    VocabularyTest vocabularyTest 

} 

我控制器的相關方法是

def save() { 
     log.debug(params) 
     def vocabularyTestInstance = new VocabularyTest(params) 
     if (!vocabularyTestInstance.save(flush: true)) { 
      render(view: "create", model: [vocabularyTestInstance: vocabularyTestInstance]) 
      return 
     } 

     flash.message = message(code: 'default.created.message', args: [message(code: 'vocabularyTest.label', default: 'VocabularyTest'), vocabularyTestInstance.id]) 
     redirect(action: "index", id: vocabularyTestInstance.id) 
    } 

上午我試圖做一些GORM和Grails將努力做的事情，或者我只是想念有什麼重要的

Answer 1

試試這個：

class VocabularyTest { 

    static hasMany = [testItems: VocabQuestion] 

    static constraints = { 
    } 

    String title 
    List testItems 
} 

class VocabQuestion { 

    static constraints = { 

    } 
    static belongsTo = [vocabularyTest: VocabularyTest] 

    String question 
    String answer 
}