Question

从Grails开始我已经安装了Grails版本2.4.0并在GNU / Linux上使用JDK 1.7.0_55我执行下面的操作序列，但不断获得NullPointerException。有人能指出我错过或做错的事吗？

grails create-app firstgrails

cd firstgrails

grails

grails> run-app

我转到localhost：8080 / firstgrails并查看生成的页面。

接下来我做

grails> create-domain-class tag

然后转到firstgrails / grails-app / domain / firstgrails文件夹并编辑Tag.groovy，使其包含：

// Tag.groovy
package firstgrails

class Tag {
    String name
    String description
}

下一步

grails> create-controller tag

并将firstgrails / grailsapp / controllers / firstgrails / TagController.groovy编辑成

// TagController.groovy
package firstgrails

class TagController {
    static scaffold = Tag
}

我在浏览器和firstgrails中重新加载.TagController被添加到可用列表中欢迎辞下的控制器。选择它，我创建一个带有名称和描述的标签，标签按预期显示在标签列表中。但是现在每当我尝试添加第二个标签时，我都会收到500错误：内部服务器错误

URI: /firstgrails/tag/create
Class: java.lang.NullPointerException
Message: null

控制台中的跟踪是：

 Error 2014-06-03 18:28:31,714 [http-bio-8080-exec-2] ERROR errors.GrailsExceptionResolver  - NullPointerException occurred when processing request: [GET] /firstgrails/tag/create
Stacktrace follows:
Message: Error processing GroovyPageView: Error executing tag <g:form>: Error executing tag <g:render>: null
    Line | Method
->>  527 | doFilter  in /tag/create
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Caused by GrailsTagException: Error executing tag <g:form>: Error executing tag <g:render>: null
->>   35 | doCall    in /tag/create
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Caused by GrailsTagException: Error executing tag <g:render>: null
->>   30 | doCall    in /tag/create
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Caused by NullPointerException: null
->>  333 | hash      in java.util.concurrent.ConcurrentHashMap
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    988 | get       in     ''
|    141 | getValue  in grails.util.CacheEntry
|     81 | getValue  in     ''
|     73 | doCall .  in tag_create$_run_closure2_closure24
|     78 | doCall    in tag_create$_run_closure2
|     81 | run . . . in tag_create
|    189 | doFilter  in grails.plugin.cache.web.filter.PageFragmentCachingFilter
|     63 | doFilter  in grails.plugin.cache.web.filter.AbstractFilter
|   1145 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    615 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker
^    745 | run       in java.lang.Thread
| Error 2014-06-03 18:30:33,050 [http-bio-8080-exec-9] ERROR errors.GrailsExceptionResolver  - NullPointerException occurred when processing request: [GET] /firstgrails/tag/create
Stacktrace follows:
Message: Error processing GroovyPageView: Error executing tag <g:form>: Error executing tag <g:render>: null
    Line | Method
->>  527 | doFilter  in /tag/create
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Caused by GrailsTagException: Error executing tag <g:form>: Error executing tag <g:render>: null
->>   35 | doCall    in /tag/create
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Caused by GrailsTagException: Error executing tag <g:render>: null
->>   30 | doCall    in /tag/create
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Caused by NullPointerException: null
->>  333 | hash      in java.util.concurrent.ConcurrentHashMap
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    988 | get       in     ''
|    141 | getValue  in grails.util.CacheEntry
|     81 | getValue  in     ''
|     73 | doCall .  in tag_create$_run_closure2_closure24
|     78 | doCall    in tag_create$_run_closure2
|     81 | run . . . in tag_create
|    189 | doFilter  in grails.plugin.cache.web.filter.PageFragmentCachingFilter
|     63 | doFilter  in grails.plugin.cache.web.filter.AbstractFilter
|   1145 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    615 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker
^    745 | run       in java.lang.Thread
| Error 2014-06-03 18:32:21,796 [http-bio-8080-exec-5] ERROR errors.GrailsExceptionResolver  - NullPointerException occurred when processing request: [GET] /firstgrails/tag/create
Stacktrace follows:
Message: Error processing GroovyPageView: Error executing tag <g:form>: Error executing tag <g:render>: null
    Line | Method
->>  527 | doFilter  in /tag/create
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Caused by GrailsTagException: Error executing tag <g:form>: Error executing tag <g:render>: null
->>   35 | doCall    in /tag/create
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Caused by GrailsTagException: Error executing tag <g:render>: null
->>   30 | doCall    in /tag/create
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Caused by NullPointerException: null
->>  333 | hash      in java.util.concurrent.ConcurrentHashMap
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    988 | get       in     ''
|    141 | getValue  in grails.util.CacheEntry
|     81 | getValue  in     ''
|     73 | doCall .  in tag_create$_run_closure2_closure24
|     78 | doCall    in tag_create$_run_closure2
|     81 | run . . . in tag_create
|    189 | doFilter  in grails.plugin.cache.web.filter.PageFragmentCachingFilter
|     63 | doFilter  in grails.plugin.cache.web.filter.AbstractFilter
|   1145 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    615 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker
^    745 | run       in java.lang.Thread

Answer 1

我试过这个并且能够重现它。如果我们生成视图然后它被解析但没有视图它会给出错误。 grails jira中存在问题，请参阅this issue他们为其提供的补丁。

希望这有帮助。

脚手架第一个Grails应用程序时出现NullPointer异常

1 个答案: