小编Nic*_*urg的帖子

在声明导航属性时,为什么我们需要使用"virtual"关键字？我知道Code First框架以某种方式使用它来识别属性是导航属性,但我想知道如何.具体来说,我想知道它与MSDN文档中关于"虚拟"关键字的描述有何关联:http://msdn.microsoft.com/en-us/library/9fkccyh4(v = vs.80)的.aspx

我正在尝试使用客户端对象模型更新Sharepoint讨论板中的"ModifiedBy"字段.通过更改"编辑器"和"作者"字段,我可以更改列表视图中显示的"ModifiedBy".但是,一旦您点击讨论帖,那里出现的"ModifiedBy"字段(上面带有图片的字段)不会反映更改.经过实验,我发现我需要更改以纠正此字段称为"MyEditor".不幸的是,这个字段是只读的.

在下面的代码中,我尝试将字段的只读设置更改为false.当我在第一个块底部的ExecuteQuery()行之后查看Visual Studio调试器中的MyEditor字段时,它显示ReadOnlyField值实际上已设置为false.

        sharepointContext.Load(discussionList);
        sharepointContext.ExecuteQuery();
        var fields = discussionList.Fields;
        sharepointContext.Load(fields);
        sharepointContext.ExecuteQuery();
        var field = fields.GetByInternalNameOrTitle("MyEditor");
        field.ReadOnlyField = false;
        field.Update();
        sharepointContext.Load(field);
        sharepointContext.ExecuteQuery();

上面的代码执行没有问题.问题出在下一个块:

        //...Code to initialize discussionItem...
        discussionItem["MyEditor"] = 0;
        discussionItem["Editor"] = 0;
        discussionItem["Author"] = 0;
        discussionItem["Body"] = "Testing";
        discussionItem["Title"] = "Hello Worlds";
        discussionItem.Update();
        sharepointContext.Load(discussionItem);
        sharepointContext.ExecuteQuery();

当代码到达第二个块底部的ExecuteQuery()时,它会抛出一个带有以下消息的ServerException:

        Invalid data has been used to update the list item. 
        The field you are trying to update may be read only.

为了确保MyEditor字段是引发异常的字段,我注释掉了我设置它的行并再次运行代码.一切都很好.我不明白有什么不对,有人能帮帮我吗？

我试图强制JSF处理我的欢迎文件.我已将web.xml中的servlet-mapping设置为以下内容:

<servlet-mapping>
    <servlet-name>Faces Servlet</servlet-name>
    <url-pattern>*.xhtml</url-pattern>
</servlet-mapping>

但是,当我尝试在执行此操作后运行我的项目时,我得到此异常:

java.lang.NullPointerException
    at com.sun.faces.context.flash.ELFlash.loggingGetPhaseMapForReading(ELFlash.java:793)
    at com.sun.faces.context.flash.ELFlash.getPhaseMapForReading(ELFlash.java:826)
    at com.sun.faces.context.flash.ELFlash.isEmpty(ELFlash.java:484)
    at com.sun.faces.facelets.util.DevTools.writeVariables(DevTools.java:325)
    at com.sun.faces.facelets.util.DevTools.writeVariables(DevTools.java:215)
    at com.sun.faces.facelets.util.DevTools.debugHtml(DevTools.java:130)
    at com.sun.faces.renderkit.RenderKitUtils.renderHtmlErrorPage(RenderKitUtils.java:1162)
    at com.sun.faces.context.ExceptionHandlerImpl.throwIt(ExceptionHandlerImpl.java:276)
    at com.sun.faces.context.ExceptionHandlerImpl.handle(ExceptionHandlerImpl.java:142)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:119)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.apache.catalina.core.ApplicationDispatcher.doInvoke(ApplicationDispatcher.java:807)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:671)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:505)
    at org.apache.catalina.core.ApplicationDispatcher.doDispatch(ApplicationDispatcher.java:476)
    at org.apache.catalina.core.ApplicationDispatcher.dispatch(ApplicationDispatcher.java:355)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:305)
    at com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:546)
    at com.sun.faces.application.view.JspViewHandlingStrategy.executePageToBuildView(JspViewHandlingStrategy.java:364)
    at com.sun.faces.application.view.JspViewHandlingStrategy.buildView(JspViewHandlingStrategy.java:154)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:100)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
    at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) …