Grails 运行此代码时获取NullPointerException

我有一个

User

类，如下所示：

package com.grailsinaction

class User {
    String userId
    String password;
    Date dateCreated
    Profile profile
    static hasMany = [posts : Post]
        static constraints = {
        userId(size:3..20, unique:true)
        password(size:6..8, validator : { passwd,user ->
                            passwd!=user.userId
                        })
        dateCreated()
        profile(nullable:true)
        }
    static mapping = {
        profile lazy:false
    }
}

package com.grailsinaction

class Post {
    String content
    Date dateCreated;
    static constraints = {
    content(blank:false)
    }
    static belongsTo = [user:User]
}

//other code goes here
void testAccessingPost() {
        def user = new User(userId:'anto',password:'adsds').save()
        user.addToPosts(new Post(content:"First"))
        def foundUser = User.get(user.id)
        def postname = foundUser.posts.collect { it.content }
        assertEquals(['First'], postname.sort())
    }

Post

像这样上课：

package com.grailsinaction

class User {
    String userId
    String password;
    Date dateCreated
    Profile profile
    static hasMany = [posts : Post]
        static constraints = {
        userId(size:3..20, unique:true)
        password(size:6..8, validator : { passwd,user ->
                            passwd!=user.userId
                        })
        dateCreated()
        profile(nullable:true)
        }
    static mapping = {
        profile lazy:false
    }
}

package com.grailsinaction

class Post {
    String content
    Date dateCreated;
    static constraints = {
    content(blank:false)
    }
    static belongsTo = [user:User]
}

//other code goes here
void testAccessingPost() {
        def user = new User(userId:'anto',password:'adsds').save()
        user.addToPosts(new Post(content:"First"))
        def foundUser = User.get(user.id)
        def postname = foundUser.posts.collect { it.content }
        assertEquals(['First'], postname.sort())
    }

我编写了一个集成测试，如下所示：

package com.grailsinaction

class User {
    String userId
    String password;
    Date dateCreated
    Profile profile
    static hasMany = [posts : Post]
        static constraints = {
        userId(size:3..20, unique:true)
        password(size:6..8, validator : { passwd,user ->
                            passwd!=user.userId
                        })
        dateCreated()
        profile(nullable:true)
        }
    static mapping = {
        profile lazy:false
    }
}

package com.grailsinaction

class Post {
    String content
    Date dateCreated;
    static constraints = {
    content(blank:false)
    }
    static belongsTo = [user:User]
}

//other code goes here
void testAccessingPost() {
        def user = new User(userId:'anto',password:'adsds').save()
        user.addToPosts(new Post(content:"First"))
        def foundUser = User.get(user.id)
        def postname = foundUser.posts.collect { it.content }
        assertEquals(['First'], postname.sort())
    }

我使用

grails test app-integration

运行，然后得到如下错误：

Cannot invoke method addToPosts() on null object
java.lang.NullPointerException: Cannot invoke method addToPosts() on null object
    at com.grailsinaction.PostIntegrationTests.testAccessingPost(PostIntegrationTests.groovy:23

---

哪里出错了？

我猜

save（）

方法返回null。请尝试以下方法：

def user = new User(userId:'anto',password:'adsds')
user.save() // Do you even need this?
user.addToPosts(new Post(content:"First"))

根据：

如果验证失败且实例未保存，则save方法返回null，如果成功，则返回实例本身

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所以有可能你应该看看验证中出现了什么问题。。。例如，是否需要指定某些字段是可选的？（我不是Grails开发人员，只是想给你一些想法。）

快速修复：你的密码必须在6到8个字符之间（检查你的约束字段）

一个愚蠢的想法，充其量就是为密码设置一个最大大小（最终它们应该被散列，并且与原始密码没有任何相似之处）

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另一方面，我可以推荐Grails的权威指南吗？

不是Grails开发人员，而是C#Developer；）这是有效的，我犯了一个错误，违反了验证：D谢谢你的回答@Ant的研究表明，了解多种技术是可能的