Copyright notice: This article is an original article and follows
CC 4.0 BY-NC-ND
Copyright agreement. If you want to repost this article, please attach the original source link and this statement.
Source link:
https://www.v2know.com/MainPage/PreView/454
要说comboBox，你要用的最多的两个属性应该是DisplayMember和ValueMember。
可今天呢，为了整这个两个属性，弄了好几次发现是“”，想来想去，才发现是SelectedIndex_Changed被触发了，而引发的错误。
举个例子：
using (var myContext = new MyDbContext())
{
var SolutionTable = myContext.MySolutions.Where(x => x.DefenceId == DefenceId1).OrderByDescending(x => x.Rank);
//如果存在解法
if (SolutionTable.Count() != 0)
{
cbxSolution1.DataSource = SolutionTable.ToList();
//初始化Id将触发一次
cbxSolution1.ValueMember = "Id";
//初始化Name将触发一次
cbxSolution1.DisplayMember = "Name";
//初始化SelectedIndex将触发一次，即使你不特意选中0，也会触发SelectedIndex_Changed
cbxSolution1.SelectedIndex = 0;
cbxSolution1.Enabled = true;
//触发一次
cbxSolution1_SelectedIndexChanged(sender, e);
}
}
解决方案：
//先取消一下事件
cbxSolution1.SelectedIndexChanged -= cbxSolution1_SelectedIndexChanged;
//之后再加上去
cbxSolution1.SelectedIndexChanged += cbxSolution1_SelectedIndexChanged;
另外需要提醒的是：
cbxSolution1.DataSource = SolutionTable.ToList();
这里一定要ToList();
因为这里涉及到本地化的事情，在using里面的数据库上下文查询是会被释放掉的，不会保存，ToList()是一个最基本的本地化操作。
参考来源：
[1] Data binding directly to a store query (DbSet, DbQuery, DbSqlQuery) is not supported.
[2] C# Winform comboBox的常用一些属性和用法
[3] How to add items to Combobox from Entity Framework? - Stack Overflow
Today's comments have reached the limit. If you want to comment, please wait until tomorrow (UTC-Time).
There is 19h06m44s left until you can comment.