Grails的奇特性質異常

希望我沒有把太多的代碼在這裏..我有什麼，我認爲一個奇怪的問題..我有2班..Grails的奇特性質異常

class Card { 
    String customerNumber 
    String memberId 
    String cardNumber 
    String issueNumber 

    Boolean active = true 

    // Audit info .. 
    Date dateCreated 
    String createdBy 
    Integer uniqId 
}

class CardHistory extends Card { 
    static constraints = { 
     note(nullable: true, size:1..500) 
    } 

    // History note 
    String note 

    // Audit info .. 
    Date originalDateCreated 
    String originalCreatedBy 
    Integer originalUniqId 

}

和另一..

class Seat { 
... 
    Card activeCard 
}

我有一些代碼，做

產生從當前歷史記錄0

cardHistoryInstance.properties = seat.card.properties

但它拋出一個NullPointerException ..

所以我寫了這個測試吧..

def seat = Seat.get(1) 

try{ 
    def cardHistoryEntry = new CardHistory(); 
    println cardHistoryEntry.properties 
    println "properties okay .." 

    assert seat 
    println "Seat okay ..." 

    assert seat.card 
    println "Card okay ..." 

    println seat.card.dateCreated 
    println "Date okay ..." 

    .... and each of the other properties  

    println seat.card.customerNumber 
    println "customer number okay .. " 

    println "Seems okay .." 

    println seat.card.properties <---- Blows up with NPE here .. 
    println "Don't get to here" 
} 
catch(e) 
{ 
    println "OOps .. An error occurred ${e} .." 
}

所以基本上我可以在每個單獨的屬性，但通過屬性關鍵字訪問是給我一個ê..任何人都可以擺脫這個光？ Grails的1.3.6 ..

感謝

來源

2011-12-13 user566311

後從異常堆棧跟蹤，你能看到這行的原因NPE。 – 2011-12-13 22:27:37

多數民衆贊成在什麼讓我困惑..堆棧跟蹤指向我突出顯示的行.. println seat.card.properties ..它給了我一個猿，但我可以打印每個單獨的屬性！ – user566311 2011-12-13 23:59:35

不，你應該是指座椅的財產activeCard，不card：

try{ 
    def cardHistoryEntry = new CardHistory(); 
    println cardHistoryEntry.properties 
    println "properties okay .." 

    assert seat 
    println "Seat okay ..." 

    assert seat.activeCard 
    println "Card okay ..." 

    println seat.activeCard.dateCreated 
    println "Date okay ..." 

    println seat.activeCard.customerNumber 
    println "customer number okay .. " 

    println "Seems okay .." 

    println seat.activeCard.properties 
    println "Don't get to here" 
} 
catch(e) 
{ 
    println "OOps .. An error occurred ${e} .." 
}

來源

2011-12-14 07:20:58

Grails的奇特性質異常

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