使用WSS的Lists.UpdateListItems()方法之被截断的CAML
Microsoft的WSS(Windows Sharepoint Services)公开了很多用于访问和管理Sharepoint站点的方法,在调用这些方法时可以通过CAML(Collaborative Application Markup Language)进行一些操作。其中Lists.UpdateListItems()方法提供了用于向Sharepoint List增、删、改数据的方法,但是需要通过CAML语句告诉Sharepoint如何更新数据,有关如何使用CAML以及如何编写CAML进行List数据更新,读者可以参考微软的MSDN文档。
http://msdn.microsoft.com/zh-cn/library/websvclists.lists.updatelistitems.aspx
顺便再给出调用Sharepoint站点的Web Service的地址:
http://Sitename/_vit_bin/lists.asmx?op=UpdateListItems
在使用Lists.UpdateListItems方法时,所使用的用于更新数据的CAML类似于下面这样:
<Method ID="1" Cmd="New">
<Field Name="Title">Hello<Field>
<Field Name="Document">5</Field>
</Method>
<Method ID="2" Cmd="New">
<Field Name="Title" >World</Field>
<Field Name="Document">5</Field>
</Method>
</Batch>
也就是说我们可以在同一段CAML中批量操作数据。不过最近在实际应用中遇到了一个问题,那就是当我要更新的记录太多,比如20000行,可能我需要写一段特别长的CAML,这个时候当我们在程序中调用Web Service时WSS会给出这样的错误。
Some part of your SQL statement is nested too deeply. Rewrite the query or break it up into smaller queries.
就是说你所使用的CAML语句太长而被自动截断了。细心观察一下,发现被截断的CAML的前半部分已经成功执行到List中了,而后半部分没有被执行,看来我们需要自己动手来处理这个Bug了。最好的办法就是将过长的CAML分批进行处理,一部分一部分地执行。
2 /// Breaks a larg CAML query into smaller batches to avoid the error "Some part of your SQL statement is nested too deeply. Rewrite the query or break it up into smaller queries."
3 /// </summary>
4 /// <param name="listService">The SharePoint list service to execute the CAML against.</param>
5 /// <param name="listName">The name of the list to execute the CAML against.</param>
6 /// <param name="elementLargeBatch">The CAML batch list of commands to be broken up.</param>
7 /// <param name="intBatchSize">The size of batches to use. If unsure use 300, it seems to work fairly well.</param>
8 /// <returns>Returns the status of each method block posted through the updates parameter and can
9 /// be assigned to a System.Xml.XmlNode object.</returns>
10 public static XmlNode UpdateListItems(SqlClrSharePointSynchronizer.Lists.Lists listService, string listName, XmlElement elementLargeBatch, int intBatchSize)
11 {
12 // calculate useful information
13 int intMethodCount = elementLargeBatch.ChildNodes.Count;
14 int intBatchCount = (int)Math.Ceiling((double)intMethodCount / (double)intBatchSize);
15
16 // prepare xml documents for batches and results
17 XmlDocument xmlDocBatch = new XmlDocument();
18 XmlDocument xmlDocResults = new XmlDocument();
19 XmlElement elementResults = xmlDocResults.CreateElement("Results");
20
21 try
22 {
23 // for each batch
24 for (int intCurrentBatch = 0; intCurrentBatch < intBatchCount; intCurrentBatch++)
25 {
26 int intMethodStart = intCurrentBatch * intBatchSize;
27 int intMethodEnd = Math.Min(intMethodStart + intBatchSize - 1, intMethodCount - 1);
28
29 XmlElement elementSmallBatch = CreateBatch(xmlDocBatch);
30
31 // for each method in the batch
32 for (int intCurrentMethod = intMethodStart; intCurrentMethod <= intMethodEnd; intCurrentMethod++)
33 {
34 XmlElement element = (XmlElement)elementLargeBatch.ChildNodes[intCurrentMethod];
35 elementSmallBatch.AppendChild(xmlDocBatch.ImportNode(element, true));
36 }
37
38 // execute the batch
39 XmlNode nodeBatchResult = listService.UpdateListItems(listName, elementSmallBatch);
40
41 // add the results of the batch into the results xml document
42 foreach (XmlElement elementResult in nodeBatchResult.ChildNodes)
43 {
44 elementResults.AppendChild(xmlDocResults.ImportNode(elementResult, true));
45 }
46
47 // clean up
48 xmlDocBatch.RemoveAll();
49 }
50 }
51 catch (SoapException ex)
52 {
53 if (ex.Detail == null)
54 {
55 throw;
56 }
57
58 //copy the exception detail into the Message so it will be available to SQL.
59 throw new SoapException(ex.Detail.InnerText, ex.Code, ex.Actor, ex.Detail, ex);
60 }
61
62 return (XmlNode)elementResults;
63 }
64
65 /// <summary>
66 /// Create the batch element. e.g. <Batch OnError="Continue"></Batch>
67 /// </summary>
68 /// <param name="xmlDoc">The object of XmlDocument.</param>
69 /// <returns>Return the Batch element.</returns>
70 private static XmlElement CreateBatch(XmlDocument xmlDoc)
71 {
72 XmlElement elementBatch = xmlDoc.CreateElement("Batch");
73 elementBatch.SetAttribute("OnError", "Continue");
74 return elementBatch;
75 }