在 SharePoint 计时器作业中创建发布页面会引发 MissingMethodException答案

【问题标题】：Creating publishing page in in SharePoint timer job throws MissingMethodException在 SharePoint 计时器作业中创建发布页面会引发 MissingMethodException
【发布时间】：2010-09-21 14:43:46
【问题描述】：

我正在使用每隔几分钟运行的计时器作业为一个共享点站点做一个简单的新闻导入器。如果我在 Web 部件中运行下面的代码，它运行良好，但在计时器作业的 Execute 方法中运行时抛出 MissingMethodException。

完整的例外：

System.MissingMethodException was unhandled by user code
  Message="No parameterless constructor defined for this object."
  Source="mscorlib"
  StackTrace:
       at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck)
       at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache)
       at System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache)
       at System.Activator.CreateInstance(Type type, Boolean nonPublic)
       at System.Activator.CreateInstance(Type type)
       at Microsoft.SharePoint.WebPartPages.SPWebPartSerializer.get_DefaultControl()
       at Microsoft.SharePoint.WebPartPages.BinaryWebPartSerializer.Serialize(PersonalizationScope scope)
       at Microsoft.SharePoint.WebPartPages.BinaryWebPartSerializer.get_Links()
       at Microsoft.SharePoint.WebPartPages.SPWebPartManager.AddWebPartToStore(WebPart webPart, Int32 viewId, String viewGuid)
       at Microsoft.SharePoint.WebPartPages.SPWebPartManager.AddWebPartInternal(SPSupersetWebPart superset, Boolean throwIfLocked)
       at Microsoft.SharePoint.WebPartPages.SPLimitedWebPartManager.AddWebPartInternal(WebPart webPart, String zoneId, Int32 zoneIndex, Boolean throwIfLocked)
       at Microsoft.SharePoint.WebPartPages.SPLimitedWebPartManager.AddWebPart(WebPart webPart, String zoneId, Int32 zoneIndex)
       at Microsoft.SharePoint.Publishing.PublishingPage.CopyAllWebParts(String destinationPageUrlServerRelative, SPWeb destinationPageWeb, String sourcePageUrlServerRelative, SPWeb sourcePageWeb, Boolean shouldOverwriteDestinationWebParts)
       at Microsoft.SharePoint.Publishing.PublishingPageCollection.<>c__DisplayClass5.<Add>b__0()
       at Microsoft.Office.Server.Diagnostics.FirstChanceHandler.ExceptionFilter(Boolean fRethrowException, TryBlock tryBlock, FilterBlock filter, CatchBlock catchBlock, FinallyBlock finallyBlock)
       at Microsoft.Office.Server.Diagnostics.ULS.SendWatsonOnExceptionTag(ULSTagID tagID, ULSCat categoryID, String output, Boolean fRethrowException, TryBlock tryBlock, CatchBlock catchBlock, FinallyBlock finallyBlock)
       at Microsoft.SharePoint.Publishing.PublishingPageCollection.Add(String name, PageLayout layout)
       at Virtua.SharePoint.Mercator.NewsImportJob.Execute(Guid contentDbId)
       at Microsoft.SharePoint.Administration.SPTimerJobInvoke.Invoke(TimerJobExecuteData& data, Int32& result)
  InnerException:

代码：

var SPWebUri = new Uri("http://.../News/");
using (SPSite site = new SPSite(SPWebUri.AbsoluteUri))
{
    using (SPWeb web = site.OpenWeb(SPWebUri.AbsolutePath)) // tried 0x29A's anwser, but it didn't work
    // using (SPWeb web = site.OpenWeb())
    {
        web.AllowUnsafeUpdates = true;

        PublishingWeb publishingWeb = PublishingWeb.GetPublishingWeb(web);
        SPContentTypeId contentTypeId = new SPContentTypeId("...");

        PageLayout layout = publishingWeb.GetAvailablePageLayouts(contentTypeId).First(l => l.Name == "....aspx");
        PublishingPageCollection pages = publishingWeb.GetPublishingPages();

        var spFilename = "testing";

        // error line below
        var newPage = pages.Add(String.Format("{0}.aspx", spFilename), layout);

        // set newPage's fields

        // check-in and publish page
    }
}

【问题讨论】：

标签： c# sharepoint sharepoint-2007 moss timer-jobs

【解决方案1】：

不确定，但是否需要为 site.OpenWeb() 提供 url 参数如果 url 参数为空，则必须打开顶级站点。这可以解释为什么它在 Web 部件中起作用，而不是在计时器作业中起作用。详情请见MSDN - Site.OpenWeb Method。

问候

【讨论】：

不，那没用。 +1 指出另一个可能的错误 :-)

【解决方案2】：

问题是我的页面布局上有一个错误的 Web 部件。我在构造函数中使用SPContext.Current...。现在，显然，SPContext 的东西在执行计时器作业代码时不存在（也不足为奇）。

由于未处理错误，Web 部件管理器尝试将我的部件替换为ErrorWebPart（通常会告诉用户出现问题的那个）。出于某种原因，这在浏览器中显示页面时效果很好。但在计时器作业中，SharePoint 尝试使用 无参数构造函数 通过反射创建 ErrorWebPart，而在 ErrorWebPart 中未定义，整个事情就用 MissingMethodException 崩溃了。

将有问题的代码移动到CreateChildControls 方法（我有错误处理）解决了这个问题。

【讨论】：