C# 更新 Sharepoint 列表项
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Update Sharepoint List Item
提问by K-M
I got following error...
我收到以下错误...
System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.SharePoint.SPListItem.get_UniqueId() at ConsoleApplication1.Program.Main(String[] args) in Program.cs:line 21
System.NullReferenceException：未将对象引用设置为对象的实例。在 Microsoft.SharePoint.SPListItem.get_UniqueId() 在 ConsoleApplication1.Program.Main(String[] args) 在 Program.cs:line 21
running following code
运行以下代码
using (SPSite site = new SPSite("http://site/"))
{
using (SPWeb web = site.OpenWeb())
{
try
{
SPList list = web.Lists["ListName"]; // 2
SPListItem item = list.Items.Add();
Guid itemId = item.UniqueId;
SPListItem itemUpdate = web.Lists["ListName"].Items[itemId];
itemUpdate["PercentComplete"] = .45; // 45%
itemUpdate.Update();
}
catch (Exception e)
{
Console.WriteLine(e);
Console.ReadLine();
}
}
}
What's the problem?
有什么问题？
采纳答案by Rubens Farias
If you're trying to alter values for a just inserted list item, you should go with:
如果您尝试更改刚刚插入的列表项的值，您应该使用：
SPList list = web.Lists["ListName"];
//SPListItem item = list.Items.Add();
//item["PercentComplete"] = .45; // 45%
//item.Update();
SPListItemCollection items = list.GetItems(new SPQuery()
{
Query = @"<Where>
<Eq>
<FieldRef Name='Title' />
<Value Type='Text'>Desigining</Value>
</Eq>
</Where>"
});
foreach (SPListItem item in items)
{
item["PercentComplete"] = .45; // 45%
item.Update();
}
You just need to use list.Items[uniqueId]or faster list.GetItemByUniqueId(uniqueId)if you needs to find a particular item to update; what can be accomplished by using SPQueryclass.
如果您需要找到要更新的特定项目，您只需要使用list.Items[uniqueId]或更快list.GetItemByUniqueId(uniqueId)；使用SPQuery类可以完成什么。
回答by axel_c
Try calling Update () on the list before getting the UniqueID
尝试在获取 UniqueID 之前调用列表上的 Update()
SPList list = web.Lists["ListName"]; // 2
SPListItem item = list.Items.Add();
item["Title"] = "Test";
item.Update ();
list.Update ();
Guid itemId = item.UniqueId;
回答by K-M
Ruben's answer was correct but was getting few errors (may be its was only for me) therefore i tweaked little bit and then it was working fine. Below is the code which i used if anyone needs it
鲁本的回答是正确的，但几乎没有错误（可能只适合我），因此我稍微调整了一下，然后就可以正常工作了。下面是我使用的代码，如果有人需要的话
SPList list = web.Lists["ListName"];
//SPListItem item = list.Items.Add();
//item["PercentComplete"] = .45;
// 45%//item.Update();
SPQuery oQuery = new SPQuery();
oQuery.Query = @"<Where>
<Eq>
<FieldRef Name='Title' />
<Value Type='Text'>Design</Value>
</Eq>
</Where>";
SPListItemCollection collListItems = list.GetItems(oQuery);
foreach (SPListItem item in collListItems)
{ item["PercentComplete"] = .55;
item.Update();}
回答by Wout
My best quess is that your item is not yet created in the list when you do:
我最好的问题是，当您执行以下操作时，您的项目尚未在列表中创建：
Guid itemId = item.UniqueId;
SPListItem itemUpdate = web.Lists["ListName"].Items[itemId];
First do a item.Update() before requesting the uniqueId and/or getting the item back from a list.
在请求 uniqueId 和/或从列表中取回项目之前，首先执行 item.Update() 。
PS : I see no reason why you should get a second SPItem object for updating the 'PercentComplete' information.
PS：我认为没有理由您应该获得第二个 SPItem 对象来更新“PercentComplete”信息。
