将DataGridView绑定到具有EF5类的数据库，而不会向数据库发送更改 [英] Binding DataGridView to database with EF5 classes not sending changes to database

问题描述

我使用实体框架5.0 + .NET 4.5

我已经使用EF Model第一种方法创建了数据库，我想绑定 DataGridView 到使用EF类的数据库，以便数据库或 DataGridView 中的任何更改都将自动同步。

这是我的代码：

  //表单级别字段
 private BindingList< ;产品> _产品; 
 private BindingSource _productSource = new BindingSource（）; 
 
 ...形式加载事件
 //使用EF类从数据库加载数据
 var tmp = _context.BaseCategorySet.OfType< Product>（）。ToList（ ）; 
 
 //转换为IBindingList 
 _products = new BindingList< Product>（tmp）; 
 _products.AllowEdit = true; 
 _products.AllowNew = true; 
 
 _productSource.DataSource = _products; 
 
 //设置GridControl的数据源
 ProductGrid.DataSource = _productSource; 
  

我可以添加新行或更改数据，但是这些更改不会发送到数据库 - 什么是我错过了吗？

我希望找到解决方案的其他事情...

1）我添加了一个保存按钮，用于显式地将网格控件的数据更新到数据库，代码如下：

  _productSource。 EndEdit（）; 
 _context.SaveChanges（）; 
  

- >这不会导致将新记录存储到数据库中

2）我添加了一个代码来添加一些个别记录属性控件的新记录（Textboxes，DatePickers）

  var x = _context.BaseCategorySet.Create< Product>（）; 
 //设置所有x属性，值为
 //，设置在上述各个控件中
 
 _context.BaseCategorySet.Add（x）; 
 _context.SaveChanges（）; 
  

- >当我使用这种技术添加新记录时 - 它存储在数据库中，但一次更奇怪的一个行为 - 这个新记录不会自动加载到网格控件中（但应该是，因为我将数据绑定到相应的EF DbSet ...）

还有一个更奇怪的是 - 我在 DataGridView 控件中对加载到数据库的记录进行更新 - 这些更新被发送到数据库...

$ 3）从DevExpress XtraGrid 切换到stadard DataGridView 控件，但是没有帮助...

我已经搜索了关于EF数据绑定的大量主题，没有成功...

不知道这是否重要，但我在实体模型中使用继承：产品源自 UnifOfSales 和 UnitOfSales 派生自 BaseCategory 类。

还有一件事ried

我尝试了（..）。Ladislav Mrnka在这篇文章中建议的Local.ToBindingList
如何在winform中使用EF进行双向数据绑定？

它将更改发送回数据库，但更改仅存储在基类表（BaseCategory）中，但派生类也有一个表。这是我用于绑定的代码

  _context.BaseCategorySet.OfType< Product> .Load（）; 
 //我试图使用派生类与OfType< Product>确保编译器
 //知道这是派生类（Product）的实例，
 //不是基类BaseCategory，
 //但是我不能得到本地使用OfType ... 
 ProductGridView.DataSource = _context.BaseCategorySet.Local.ToBindingList（）; 
  

解决方案

我找到了解决方案！

我不得不在DbContext类中为EF模型派生类添加DbSet产品（Product，派生自BaseCategory类）

此后我可以使用

  ProductGridView.DataSource = _context.Products.Local.ToBindingList（）; 
  

I am using Entity Framework 5.0 + .NET 4.5

I have created database using EF Model first approach and I want to bind DataGridView to database using EF classes so that any changes to database or in the DataGridView are synchronized automatically.

This is my code:

//form level fields
private BindingList<Product> _products;
private BindingSource _productSource = new BindingSource(); 

... in the form load event
//load the data from database using EF classes
var tmp = _context.BaseCategorySet.OfType<Product>().ToList();

//converting to IBindingList
_products = new BindingList<Product>(tmp);
_products.AllowEdit = true;
_products.AllowNew = true;

_productSource.DataSource = _products; 

//setting GridControl's data source
ProductGrid.DataSource = _productSource;

I can add new rows or change data, but those changes are not sent to the database - what am I missing?

Additional things I did in hope to find a solution...

1) I added a Save button to call updating the grid control's data to database explicitly, with code:

_productSource.EndEdit();
_context.SaveChanges();

->this did not result in storing the new record into the database

2) I added a code to add new records with a bunch of controls for individual record properties (Textboxes, DatePickers)

var x = _context.BaseCategorySet.Create<Product>();
//settting all the x properties with values
//that are set in aforementioned individual controls

_context.BaseCategorySet.Add(x);
_context.SaveChanges();

-->when I add new records using this technique - it IS stored in the database, but once more a strange behavior - this new record is not automatically loaded in the grid control (but should be, since I am databinding grid to the corresponding EF DbSet...)

And one more strangeness - updates that I have made in the DataGridView control to the records that were loaded to database - those updates ARE sent to database...

3) I switched from DevExpress XtraGrid to stadard DataGridView control, but that did not help...

I have searched through tons of topics regarding EF databinding with no success...

Don't know if this matters, but I am using inheritance in my Entity model: Product derives from UnifOfSales and UnitOfSales derives from BaseCategory class.

One more thing i tried

I tried the (..).Local.ToBindingList that was suggested by Ladislav Mrnka in this post How to make two way-databinding using EF in winforms?

well it did send changes back to the database, but the changes were stored only in the base class table (BaseCategory), but there is a table for derived class as well. This is the code i used for binding

_context.BaseCategorySet.OfType<Product>.Load(); 
//i tried to use derived class with OfType<Product> to ensure that compiler
//knows that this is instance of derived class (Product), 
//not the base class BaseCategory, 
//but I can not get "Local" working with OfType...
ProductGridView.DataSource = _context.BaseCategorySet.Local.ToBindingList(); 

解决方案

I did find the solution!

I had to add DbSet Products in DbContext class for EF model derived class (Product, derived from BaseCategory class)

After this I could use

ProductGridView.DataSource=_context.Products.Local.ToBindingList();

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