DataGridView的AllowUserToAddRow属性不起作用 [英] DataGridView AllowUserToAddRow property doesn't work

问题描述

我有2个问题。

第一个问题是我有一个简单的项目实体框架，我有一个 DataGridView的在我的表格，我设置其 AllowUserToAddRow 属性真正但我仍然不能添加新行到它。

First problem is I have a simple project with Entity Framework, I have a DataGridView in my Form and I set its AllowUserToAddRow property to true but still I can not add new rows into it.

的这里是截图，看看我的 DataGridView的看起来像在运行时。

Here is a screenshot to see how my DataGridView looks like in run-time.

这是我的代码：

DBEntities context = new DBEntities();
private void Form1_Load(object sender, EventArgs e)
{
    var q = (from i in context.myTable
             select i).ToList();
    DataGridView.DataSource = q;
}

private void btnSave_Click(object sender, EventArgs e)
{
    context.SaveChanges();
    MessageBox.Show("saved successfully");
}

第二个问题是如果我使用的BindingSource 控制，它让我插入的DataGridView行但这种方法我称之为后 context.SaveChanges（）在我的数据库文件中没有插入。所以我想也许它相对于这个问题 DataGridView的与真正 AllowUserToAddRow 属性不会让我在 DataGridView的插入一行。

Second problem is If I use a BindingSource control, it allow me to insert rows in DataGridView but with this approach after I call context.SaveChanges() nothing insert in my database file. So I thought maybe its relative to this problem that DataGridView with true AllowUserToAddRow property doesn't let me to insert row in DataGridView.

推荐答案

您的问题是，你叫 .ToList（）和物化查询 - 这似乎打破了完整的数据绑定

Your problem is that you call .ToList() and materialize your query - this appears to break the full databinding.

您应可以简单地有：

DBEntities context = new DBEntities();
private void Form1_Load(object sender, EventArgs e)
{
    var q = (from i in context.myTable
             select i);
    DataGridView.DataSource = q;
}

我尝试这样做，它允许新行正常工作（你需要在你的表的主键，但你应该有一个反正）

I tried this and it works fine for allowing new rows (you do need to have a primary key in your table but you should have that anyway).

请注意： - >此行为在实体框架4.1被有意打破Web表单数据和EF代码优先Linq查询错误

Do Note: this behaviour has been intentionally broken in Entity Framework 4.1 - Webforms data binding with EF Code-First Linq query error

我说的应在我的答案，因为我其实是有点惊讶正是这种容易。我记得它不是在早期版本的实体框架的工作这么好，我没有用4.0非常多。

I say should in my answer because I'm actually a little surprised it is this easy. I recall it not working so nicely in earlier versions of Entity Framework and I haven't used 4.0 very much.

如果上述解决方案不工作，你可能要做这硬的方式，并在保存前将自己添加新的对象：

If the solution above doesn't work you may have to do this the hard way and add new objects yourself before saving:

先介绍一个绑定源并在保存像做（与客户在例如一个假想的实体）：

First introduce a binding source and when you save do something like (with an imaginary entity of Customer in the example):

foreach (Customer customer in bs.List)
{         
    // In my db customerId was an identity column set as primary key
    if (customer.CustomerId == 0)
        context.Customers.AddObject(customer);
}
context.SaveChanges();

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