C# 如何从实体框架向 Combobox 添加项目？
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How to add items to Combobox from Entity Framework?
提问by Saleh
I have this code:
我有这个代码：
private void FillCombobox()
{
using (InventoryEntities c = new InventoryEntities(Properties.Settings.Default.Connection))
{
List<Customer> usepurposes = c.Customers.ToList();
DataTable dt = new DataTable();
dt.Columns.Add("id");
dt.Columns.Add("name");
foreach (Customer usepurpose in usepurposes)
{
dt.Rows.Add(usepurpose.id, usepurpose.name);
}
comboBox1.ValueMember = dt.Columns[0].ColumnName;
comboBox1.DisplayMember = dt.Columns[1].ColumnName;
comboBox1.DataSource = dt;
}
}
and I call this method in:
我把这个方法称为：
private void frmBillIn_Load(object sender, EventArgs e)
{
FillCombobox();
}
When I run my app, combobox will not display customers(items).
当我运行我的应用程序时，组合框不会显示客户（项目）。
just display Model.Customer
只显示Model.Customer
What is the problem??
问题是什么？？
I tried many solution but non of them are working.
我尝试了很多解决方案，但没有一个有效。
采纳答案by Wiktor Zychla
You don't have to mix two worlds, the world of Entity Framework and the world of DataSets. Bind directly:
您不必混合两个世界，实体框架的世界和数据集的世界。直接绑定：
using (InventoryEntities c = new InventoryEntities(Properties.Settings.Default.Connection))
{
comboBox1.DataSource = c.Customers;
comboBox1.ValueMember = "id";
comboBox1.DisplayMember = "name";
}
If this does not work, then the column name could be different from "name" ("Name" perhaps?).
如果这不起作用，那么列名可能与“名称”不同（也许是“名称”？）。
回答by Xilmiki
If you use "using" you need to place a ToList() for evaluate before close connection. use ItemsSource , ValueMember and DisplayMember are case sensitive
如果您使用“使用”，则需要在关闭连接之前放置一个 ToList() 进行评估。使用 ItemsSource 、 ValueMember 和 DisplayMember 区分大小写
using (InventoryEntities c = new InventoryEntities())
{
comboBox1.ItemsSource = c.Customers.toList();
comboBox1.ValueMemberPath = "Id";
comboBox1.DisplayMemberPath = "Name";
}
Hope this help.
希望这有帮助。
回答by Raj
Refer following sample. (name references => DAL=Data access layer, projectEntities = entity set name) Hope this will help..
请参阅以下示例。（名称引用 => DAL=数据访问层，projectEntities = 实体集名称）希望这会有所帮助..
List itemsList = new List();
List itemsList = new List();
using (DAL.projectEntities en = new DAL.projectEntities())
{
foreach (var item in en.tableName.Where(a => a.tableName != null).ToList())
{
itemsList.Add(item.tableFieldName);
}
}
comboboxTable.ItemsSource = itemsList;
回答by pat capozzi
In the current version of WinForms I have found this to work
在当前版本的 WinForms 中，我发现它可以工作
RentalsEntities1 db = new RentalsEntities1();
List<SiteSeeingLocation> ssloc = db.SiteSeeingLocations.ToList();
cbSites.DataSource = ssloc;
cbSites.ValueMember = "id";
cbSites.DisplayMember = "ssLocation";
