问题描述
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我正在尝试使用LINQ更新记录,但出现此错误:
Property or indexer \'AnonymousType#1.Comment\' cannot be assigned to -- it is read only
Property or indexer \'AnonymousType#1.LastEdit\' cannot be assigned to -- it is read only
这是在网上抛出的:
// Update parent comment
q.Comment = EditedText;
q.LastEdit = DateTime.Now;
完整课程如下:
/// <summary>
/// Creates a new edit for a comment
/// </summary>
/// <param name=\"CommentID\">ID of comment we are editing</param>
/// <param name=\"EditedText\">New text for comment</param>
/// <param name=\"UserID\">ID of user making the edit</param>
/// <returns>Status</returns>
public static CommentError NewEdit(int CommentID,string EditedText,int UserID)
{
CommentError Status = CommentError.UnspecifiedError;
using (DataClassesDataContext db = new DataClassesDataContext())
{
bool IsOriginalAuthor = false;
var q = (from c in db.tblComments where c.ID == CommentID select new { c.UserID,c.PostDate,c.Comment,c.LastEdit }).Single();
if (q == null)
Status = CommentError.UnspecifiedError;
else
{
if (q.UserID == UserID)
IsOriginalAuthor = true;
// Check if they are within lock time
bool CanEdit = true;
if (IsOriginalAuthor)
{
if (q.PostDate.AddMinutes(Settings.MinsUntilCommentLockedFromEdits) > DateTime.Now)
{
Status = CommentError.CommentNowUneditable;
CanEdit = false;
}
}
// Passed all checks,create edit.
if (CanEdit)
{
// Update parent comment
q.Comment = EditedText;
q.LastEdit = DateTime.Now;
// New edit record
tblCommentEdit NewEdit = new tblCommentEdit();
NewEdit.CommentID = CommentID;
NewEdit.Date = DateTime.Now;
NewEdit.EditedText = EditedText;
NewEdit.UserID = UserID;
db.tblCommentEdits.InsertOnSubmit(NewEdit);
db.SubmitChanges();
Status = CommentError.Success;
}
}
}
return Status;
}
解决方法
因为您做了
select new { c.UserID,c.PostDate,c.Comment,c.LastEdit }
,所以引发错误。如果您执行select c
,则您的代码应该可以正常工作。
new {...}
为您提供匿名类型,该类型不可更新。
,根据错误消息q是匿名类型...
var q = (from c in db.tblComments where c.ID == CommentID select new { c.UserID,c.LastEdit }).Single();
您不想更新该对象...更新LINQ语句中c引用的对象(选择它)