我收到此错误：收集已修改;枚举操作可能无法执行。
问题描述：
您好b $ b
我有这个问题。我有这个带有数量的文本框，可以根据需要进行更改。我第一次做出改变是有效的，但第二次我得到这个错误收集被修改了;枚举操作可能无法执行。
我不知道错误是什么。这是我的清单吗？
这是完整的错误代码：
Hi
I have this issue. I have this textbox with quantity, and it could be possible to make an change as much as you like. The first time I make a change it works, but the second time I got this error Collection was modified; enumeration operation may not execute.
And I don´t have any clue what the error is. It is something about my list?
Here is the fulll error code:
Line 83: List<OrdreNew> produktOrdreNew = new List<OrdreNew>();
Line 84:
Line 85: foreach (RepeaterItem items in Repeater1.Items)
Line 86: {
Line 87:
[InvalidOperationException: Collection was modified; enumeration operation may not execute.]
System.Collections.ArrayListEnumeratorSimple.MoveNext() +11165697
kassen.Button1_Click(Object sender, EventArgs e) in c:\Users\Tina\Desktop\tojbutik\kassen.aspx.cs:85
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +9628026
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +103
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +35
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1724
这是我的代码：
And here is my code:
public partial class kassen : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
Repeater1.Visible = false;
List<Produkt> produkter = Session["OrdreComplete"] as List<Produkt>;
List<ordre> produktOrdre = new List<ordre>();
foreach (var produkt in produkter)
{
produktOrdre.Add(new ordre { produktID = produkt.ID, Produktoverskrift = produkt.overSkrift, produktStr = produkt.STR, produktAntal = produkt.Antal, produktPris = produkt.PRICE });
}
this.RepeaterVisOrdre.DataSource = produktOrdre;
this.RepeaterVisOrdre.DataBind();
}
}
protected void RepeaterVisOrdre_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
{
DataRowView row = e.Item.DataItem as DataRowView;
Label LabelID = e.Item.FindControl("LabelID") as Label;
Label LabelVare = e.Item.FindControl("LabelVare") as Label;
Label LabelStr = e.Item.FindControl("LabelStr") as Label;
Label LabelPris = e.Item.FindControl("LabelPris") as Label;
TextBox TextBox1 = e.Item.FindControl("TextBox1") as TextBox;
TextBox tb = (TextBox)e.Item.FindControl("TextBox1");
//LabelVare.Attributes.Add("IDprodukt", string.Format("{0}", row["LabelVare"]));
//LabelVare.Attributes.Add("vareBeskriv", string.Format("{0}", row["overskriftt"]));
//LabelStr.Attributes.Add("STR", string.Format("{0}", row["produktStr"]));
//LabelPris.Attributes.Add("PRICE", string.Format("{0}", row["str"]));
//LabelAntal.Attributes.Add("Antal", string.Format("{0}", row["produktAntal"]));
//TextBox1.Attributes.Add("Antal", string.Format("{0}", row["produktAntal"]));
}
}
protected void Button1_Click(object sender, EventArgs e)
{
if (Session["Ordre"] != null)
{
List<OrdreNew> produktOrdreNew = new List<OrdreNew>();
foreach (RepeaterItem items in Repeater1.Items)
{
if (items.ItemType == ListItemType.Item || items.ItemType == ListItemType.AlternatingItem)
{
Label LabelID = (Label)items.FindControl("LabelID");
Label LabelVare = (Label)items.FindControl("LabelVare");
Label LabelStr = (Label)items.FindControl("LabelStr");
Label LabelPris = (Label)items.FindControl("LabelPris");
TextBox tb = (TextBox)items.FindControl("TextBox1");
int id = Convert.ToInt32(LabelID.Text);
int newAntal = Convert.ToInt32(tb.Text);
string vare = LabelVare.Text;
string str = LabelStr.Text;
int prise = Convert.ToInt32(LabelPris.Text);
produktOrdreNew.Add(new OrdreNew() { produktID = id, Produktoverskrift = vare, produktStr = str, produktAntal = newAntal, produktPris = prise });
Repeater1.Visible = true;
Repeater1.DataSource = produktOrdreNew;
Repeater1.DataBind();
RepeaterVisOrdre.Visible = false;
}
}
Session["OrdreNew"] = produktOrdreNew;
List<OrdreNew> produktOrdreNew1 = (List<OrdreNew>)Session["OrdreNew"];
foreach (OrdreNew produkt in produktOrdreNew1)
{
Label1.Text += "Label fra repeater 1 ID " + produkt.produktID + " " + "Vare nr :" + produkt.Produktoverskrift + " " + "Størrelse :" + produkt.produktStr + " " + " Antal : " + produkt.produktAntal + " " + " Pris : " + produkt.produktPris;
}
}
else
{
List<ordreEnd> produkt1 = new List<ordreEnd>();
foreach (RepeaterItem item in RepeaterVisOrdre.Items)
{
if (item.ItemType == ListItemType.Item || item.ItemType == ListItemType.AlternatingItem)
{
Label LabelID = (Label)item.FindControl("LabelID");
Label LabelVare = (Label)item.FindControl("LabelVare");
Label LabelStr = (Label)item.FindControl("LabelStr");
Label LabelPris = (Label)item.FindControl("LabelPris");
TextBox tb = (TextBox)item.FindControl("TextBox1");
int id = Convert.ToInt32(LabelID.Text);
int newAntal = Convert.ToInt32(tb.Text);
string vare = LabelVare.Text;
string str = LabelStr.Text;
int prise = Convert.ToInt32(LabelPris.Text);
produkt1.Add(new ordreEnd() { produktID = id, Produktoverskrift = vare, produktStr = str, produktAntal = newAntal, produktPris = prise });
Repeater1.Visible = true;
Repeater1.DataSource = produkt1;
Repeater1.DataBind();
RepeaterVisOrdre.Visible = false;
}
}
Session["Ordre"] = produkt1;
List<ordreEnd> valgteFrugter = (List<ordreEnd>)Session["Ordre"];
foreach (ordreEnd produkt in valgteFrugter)
{
Label1.Text += "Label fra repeaterVisOrdre ID " + produkt.produktID + " " + "Vare nr :" + produkt.Produktoverskrift + " " + "Størrelse :" + produkt.produktStr + " " + " Antal : " + produkt.produktAntal + " " + " Pris : " + produkt.produktPris;
}
}
}
protected void LinkButton1_Click(object sender, EventArgs e)
{
Session.Abandon();
}
}
希望有人能帮我解决这个错误
Hope someone could help me with this error
答
当您执行此操作时，将根据数据源填充项目：
Items are populated based on Datasource, when you do this:
Repeater1.DataSource = produktOrdreNew;
Repeater1.DataBind();
那么你有不同的项目：
then you have different items in:
Repeater1.Items
http ：//msdn.microsoft.com/pl-pl/library/system.web.ui.webcontrols.repeater.items（v = vs.110）.aspx [ ^ ]
我想如果你在循环外移动DataSource赋值和DataBind（）会有所帮助。
http://msdn.microsoft.com/pl-pl/library/system.web.ui.webcontrols.repeater.items(v=vs.110).aspx[^]
I guess it should help if you move DataSource assignment and DataBind() outside the loop.
尝试使用for循环当您修改正在迭代的集合中的对象时，迭代集合而不是foreach。
请参阅Jared Par的代码：[ ^ ];该线程对这个问题的不同方面进行了很好的讨论。
允许你使用foreach迭代器的另一个策略是在对象的foreach迭代器中构建一个List你希望修改，然后，在迭代完成后，通过遍历该列表来修改那些对象。
删除时的常用策略使用for循环的Collection中的项目以端到端的顺序遍历循环，以便索引保持有意义。
另一个策略是投射你的无论你在迭代到另一个List，甚至是一个允许你使用foreach的数组。
给出这样的字典：
Try using for-loops to iterate over the collection instead of foreach when you modify objects in the collection you are iterating over.
See Jared Par's code here: [^]; that thread has a good discussion of different aspects of this problem.
Another strategy that allows you to use a foreach iterator is to build a List in the foreach iterator of objects you wish to modify, and then, after the iteration is complete, modify only those objects by iterating over that List.
A common strategy when removing items from a Collection using a for-loop is traverse the loop in end-to-front order so that indexes remain meaningful.
Another strategy is to Cast your whatever-you-are-iterating to another List, or even an Array, which lets you use foreach.
Given a Dictionary like this:
Dictionary<string,> dctStrStr = new Dictionary<string,>
{
{"1", "1"},
{"2", "2"},
{"3", "3"},
{"4", "4"},
{"5", "5"},
};这将失败：收集修改错误：
This will fail: collection modified error:
foreach (var theKey in dctStrStr.Keys)
{
dctStrStr[theKey] += " modified";
}这没关系：
foreach (var theKey in dctStrStr.Keys.ToList())
{
dctStrStr[theKey] += " modified";
}这没关系：
foreach (string sKey in dctStrStr.Select(kvp => kvp.Key).ToList())
{
dctStrStr[sKey] += " modified";
}