Question

我有三个域对象定义为：

class Member {
    String name

    static constraints = {}
    static belongsTo=[community:Community]
}

class Community {
    String leaderName
    String code

    static constraints = {}
    static hasMany=[members: Member]
    static belongsTo=[bank:Bank]
}

class Bank {

    String bankName
    static hasMany=[communities: Community]
    static constraints = {}
}

当我尝试使用BootStrap.groovy配置类中的一些测试数据初始化这些域对象时：

 def init = { servletContext ->

            def m1 = new Member(name:"M1_Name")
            def m2 = new Member(name:"M2_Name")
            def m3 = new Member(name:"M3_Name")

            m1.save(failOnError:true)
            m2.save(failOnError:true)
            m3.save(failOnError:true)

            def comA = new Community(leaderName:"LeaderA", code:"AA")
            def comB = new Community(leaderName:"LeaderB", code:"BB")

            comA.addToMembers(m1)
            comA.addToMembers(m2)
            comB.addToMembers(m3)

            comA.save(failOnError:true)
            comB.save(failOnError:true)

            def bankA = new Bank(bankName:"BankA")
            def bankB = new Bank(bankName:"BankB")

            bankA.addToCommunities(comA)
            bankB.addToCommunities(comB)

            bankA.save(failOnError:true)
            bankB.save(failOnError:true)
        }

我收到以下错误：

| Loading Grails 2.0.4
| Configuring classpath.
| Environment set to development.....
| Packaging Grails application.....
| Compiling 3 source files.....
| Running Grails application
| Error 2012-07-13 22:14:44,798 [pool-5-thread-1] ERROR context.GrailsContextLoader  - Error executing bootstraps: Validation Error(s) occurred during save():
- Field error in object 'mygrailtests.Member' on field 'community': rejected value [null]; codes [mygrailtests.Member.community.nullable.error.mygrailtests.Member.community,mygrailtests.Member.community.nullable.error.community,mygrailtests.Member.community.nullable.error.mygrailtests.Community,mygrailtests.Member.community.nullable.error,member.community.nullable.error.mygrailtests.Member.community,member.community.nullable.error.community,member.community.nullable.error.mygrailtests.Community,member.community.nullable.error,mygrailtests.Member.community.nullable.mygrailtests.Member.community,mygrailtests.Member.community.nullable.community,mygrailtests.Member.community.nullable.mygrailtests.Community,mygrailtests.Member.community.nullable,member.community.nullable.mygrailtests.Member.community,member.community.nullable.community,member.community.nullable.mygrailtests.Community,member.community.nullable,nullable.mygrailtests.Member.community,nullable.community,nullable.mygrailtests.Community,nullable]; arguments [community,class mygrailtests.Member]; default message [Property [{0}] of class [{1}] cannot be null]

Message: Validation Error(s) occurred during save():
- Field error in object 'mygrailtests.Member' on field 'community': rejected value [null]; codes [mygrailtests.Member.community.nullable.error.mygrailtests.Member.community,mygrailtests.Member.community.nullable.error.community,mygrailtests.Member.community.nullable.error.mygrailtests.Community,mygrailtests.Member.community.nullable.error,member.community.nullable.error.mygrailtests.Member.community,member.community.nullable.error.community,member.community.nullable.error.mygrailtests.Community,member.community.nullable.error,mygrailtests.Member.community.nullable.mygrailtests.Member.community,mygrailtests.Member.community.nullable.community,mygrailtests.Member.community.nullable.mygrailtests.Community,mygrailtests.Member.community.nullable,member.community.nullable.mygrailtests.Member.community,member.community.nullable.community,member.community.nullable.mygrailtests.Community,member.community.nullable,nullable.mygrailtests.Member.community,nullable.community,nullable.mygrailtests.Community,nullable]; arguments [community,class mygrailtests.Member]; default message [Property [{0}] of class [{1}] cannot be null]

   Line | Method
->>  13 | doCall                           in BootStrap$_closure1
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|   301 | evaluateEnvironmentSpecificBlock in grails.util.Environment
|   294 | executeForEnvironment . . . . .  in     ''
|   270 | executeForCurrentEnvironment     in     ''
|   303 | innerRun . . . . . . . . . . . . in java.util.concurrent.FutureTask$Sync
|   138 | run                              in java.util.concurrent.FutureTask
|   886 | runTask . . . . . . . . . . . .  in java.util.concurrent.ThreadPoolExecutor$Worker
|   908 | run                              in     ''
^   662 | run . . . . . . . . . . . . . .  in java.lang.Thread

这里，第13行是

m1.save(failOnError:true)

你能告诉我发生了什么事吗？或者我错过了什么。

更新： 当我删除belongsTo和Member个对象中的Community关系时，它正常运行。

Answer 1

当您将belongsTo: Community部分添加到Member时，您说Member将属于Community。

构建Member对象时，您未提供与Community相关联的Member。像这样提交Member正在爆发，因为你尚未说出它所属的Community。

无论如何，您不需要那些save来电，因为belongsTo标记Community将负责保存。取出3 m [x] .save（）行，读取belongsTo代码，看看它是否按预期工作。

Answer 2

它是对象创建的顺序。 belongsTo将创建外键关系（至少在默认情况下是这样），因此您必须按照示例中显示的相反顺序创建对象（例如，Bank，Community，Member）。

您还可以更深入地了解约束和映射以更改某些默认机制。 Grails指南相当长，有时我发现它假设了一些Hibernate的先前知识，但它应该具有相当多的大部分内容（你可能必须转到“其他”和“高级”主题）。

Grails - 保存域对象时 - 我收到“被拒绝的值[null]错误”

2 个答案: