2

我将三个域对象定义为：

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

在这里，第 13 行是

m1.save(failOnError:true)

你能告诉我发生了什么问题吗？或者我错过了什么。

更新： 当我删除和对象中belongsTo的关系时，它可以正常工作。MemberCommunity

4

2 回答 2

4

当您添加该belongsTo: Community部分时，Member您会说这Member将属于一个Community.

构造Member对象时，您没有提供Community与Member. 犯下Member这样的事情会爆炸，因为你还没有Community说它属于。

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

于 2012-07-13T16:53:55.940 回答
1

它的对象创建顺序。belongsTo 将创建一个外键关系（至少在默认情况下），因此您必须以与示例中显示的相反顺序创建对象（例如银行、社区、成员）。

您还可以更深入地了解约束和映射，以更改一些默认机制。Grails 指南相当长，有时我发现它假定了一些以前的 Hibernate 知识，但它应该包含大部分内容（您可能必须深入到“其他”和“高级”主题）。

于 2012-07-13T16:57:31.240 回答