我正在关注本教程Creating Master-Details Windows Forms with the Entity Framework
但是如果我修改了一些列或添加了一个新行，则db.Savechanges()无效。根据这个视频教程，它可以工作，但事实并非如此。
Product_Form.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace RemoteSynchronizer
{
public partial class Product : Form
{
ProductsEntities db = new ProductsEntities();
public Product()
{
InitializeComponent();
}
private void Product_Form_Load(object sender, EventArgs e)
{
product_DBindingSource.DataSource = db.Product_D.ToList();
}
private void bindingNavigatorAddNewItem_Click(object sender, EventArgs e)
{
}
private void product_DBindingNavigatorSaveItem_Click(object sender, EventArgs e)
{
// Product_D obj = new Product_D();
// obj.PCode = pCodeTextBox.Text;
// obj.Name = nameTextBox.Text;
// obj.Batch = batchTextBox.Text;
// obj.Expiry = expiryTextBox.Text;
// obj.Price = priceTextBox.Text;
//try
// {
// Product_D temp = db.Product_D.Single(t => t.PCode == pCodeTextBox.Text);
// MessageBox.Show("Product Exists");
// }
// catch
// {
// db.Product_D.Add(obj);
db.SaveChanges();
//}
}
private void bindingNavigatorDeleteItem_Click(object sender, EventArgs e)
{
}
}
}
当我尝试在代码中使用comment方法时会出现错误
错误
************** Exception Text **************
System.Data.Entity.Infrastructure.DbUpdateException: Unable to update the EntitySet 'Product_D' because it has a DefiningQuery and no <InsertFunction> element exists in the <ModificationFunctionMapping> element to support the current operation. ---> System.Data.UpdateException: Unable to update the EntitySet 'Product_D' because it has a DefiningQuery and no <InsertFunction> element exists in the <ModificationFunctionMapping> element to support the current operation.
at System.Data.SqlClient.SqlGen.DmlSqlGenerator.ExpressionTranslator.Visit(DbScanExpression expression)
at System.Data.Common.CommandTrees.DbScanExpression.Accept(DbExpressionVisitor visitor)
at System.Data.SqlClient.SqlGen.DmlSqlGenerator.GenerateInsertSql(DbInsertCommandTree tree, SqlVersion sqlVersion, List`1& parameters)
at System.Data.SqlClient.SqlGen.SqlGenerator.GenerateSql(DbCommandTree tree, SqlVersion sqlVersion, List`1& parameters, CommandType& commandType, HashSet`1& paramsToForceNonUnicode)
at System.Data.SqlClient.SqlProviderServices.CreateCommand(DbProviderManifest providerManifest, DbCommandTree commandTree)
at System.Data.SqlClient.SqlProviderServices.CreateCommand(DbCommandTree commandTree)
at System.Data.Mapping.Update.Internal.UpdateTranslator.CreateCommand(DbModificationCommandTree commandTree)
at System.Data.Mapping.Update.Internal.DynamicUpdateCommand.CreateCommand(UpdateTranslator translator, Dictionary`2 identifierValues)
at System.Data.Mapping.Update.Internal.DynamicUpdateCommand.Execute(UpdateTranslator translator, EntityConnection connection, Dictionary`2 identifierValues, List`1 generatedValues)
at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter)
at System.Data.EntityClient.EntityAdapter.Update(IEntityStateManager entityCache)
at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)
at System.Data.Entity.Internal.InternalContext.SaveChanges()
--- End of inner exception stack trace ---
at System.Data.Entity.Internal.InternalContext.SaveChanges()
at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
at System.Data.Entity.DbContext.SaveChanges()
at RemoteSynchronizer.Product.product_DBindingNavigatorSaveItem_Click(Object sender, EventArgs e) in e:\Study\Project\RemoteSynchronizer\RemoteSynchronizer\Product_Form.cs:line 50
at System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e)
at System.Windows.Forms.ToolStripButton.OnClick(EventArgs e)
at System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)
at System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)
at System.Windows.Forms.ToolStripItem.FireEventInteractive(EventArgs e, ToolStripItemEventType met)
at System.Windows.Forms.ToolStripItem.FireEvent(EventArgs e, ToolStripItemEventType met)
at System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ToolStrip.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
************** Loaded Assemblies **************
mscorlib
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.18010 built by: FX45RTMGDR
CodeBase: file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/mscorlib.dll
----------------------------------------
RemoteSynchronizer
Assembly Version: 1.0.0.0
Win32 Version: 1.0.0.0
CodeBase: file:///E:/Study/Project/RemoteSynchronizer/RemoteSynchronizer/bin/Debug/RemoteSynchronizer.exe
----------------------------------------
System.Windows.Forms
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Windows.Forms/v4.0_4.0.0.0__b77a5c561934e089/System.Windows.Forms.dll
----------------------------------------
System.Drawing
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Drawing/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll
----------------------------------------
System
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.18016 built by: FX45RTMGDR
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System/v4.0_4.0.0.0__b77a5c561934e089/System.dll
----------------------------------------
System.Configuration
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Configuration/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Configuration.dll
----------------------------------------
System.Xml
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Xml/v4.0_4.0.0.0__b77a5c561934e089/System.Xml.dll
----------------------------------------
System.Web
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_32/System.Web/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Web.dll
----------------------------------------
System.Core
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Core/v4.0_4.0.0.0__b77a5c561934e089/System.Core.dll
----------------------------------------
EntityFramework
Assembly Version: 5.0.0.0
Win32 Version: 5.0.20627.0
CodeBase: file:///E:/Study/Project/RemoteSynchronizer/RemoteSynchronizer/bin/Debug/EntityFramework.DLL
----------------------------------------
System.Data.Entity
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Data.Entity/v4.0_4.0.0.0__b77a5c561934e089/System.Data.Entity.dll
----------------------------------------
Anonymously Hosted DynamicMethods Assembly
Assembly Version: 0.0.0.0
Win32 Version: 4.0.30319.18010 built by: FX45RTMGDR
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_32/mscorlib/v4.0_4.0.0.0__b77a5c561934e089/mscorlib.dll
----------------------------------------
Accessibility
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/Accessibility/v4.0_4.0.0.0__b03f5f7f11d50a3a/Accessibility.dll
----------------------------------------
System.Data
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_32/System.Data/v4.0_4.0.0.0__b77a5c561934e089/System.Data.dll
----------------------------------------
System.Transactions
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_32/System.Transactions/v4.0_4.0.0.0__b77a5c561934e089/System.Transactions.dll
----------------------------------------
System.Numerics
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Numerics/v4.0_4.0.0.0__b77a5c561934e089/System.Numerics.dll
----------------------------------------
System.Data.OracleClient
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_32/System.Data.OracleClient/v4.0_4.0.0.0__b77a5c561934e089/System.Data.OracleClient.dll
----------------------------------------
System.Xml.Linq
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Xml.Linq/v4.0_4.0.0.0__b77a5c561934e089/System.Xml.Linq.dll
----------------------------------------
System.EnterpriseServices
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_32/System.EnterpriseServices/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.EnterpriseServices.dll
----------------------------------------
EntityFrameworkDynamicProxies-RemoteSynchronizer
Assembly Version: 1.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Data.Entity/v4.0_4.0.0.0__b77a5c561934e089/System.Data.Entity.dll
----------------------------------------
System.Runtime.Serialization
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929 built by: FX45RTMREL
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.Runtime.Serialization/v4.0_4.0.0.0__b77a5c561934e089/System.Runtime.Serialization.dll
----------------------------------------
System.ComponentModel.DataAnnotations
Assembly Version: 4.0.0.0
Win32 Version: 4.0.30319.17929
CodeBase: file:///C:/Windows/Microsoft.Net/assembly/GAC_MSIL/System.ComponentModel.DataAnnotations/v4.0_4.0.0.0__31bf3856ad364e35/System.ComponentModel.DataAnnotations.dll
----------------------------------------
Microsoft.SqlServer.Types
Assembly Version: 11.0.0.0
Win32 Version: 2011.0110.2100.060 ((SQL11_RTM).120210-1917 )
CodeBase: file:///C:/Windows/assembly/GAC_MSIL/Microsoft.SqlServer.Types/11.0.0.0__89845dcd8080cc91/Microsoft.SqlServer.Types.dll
----------------------------------------
************** JIT Debugging **************
To enable just-in-time (JIT) debugging, the .config file for this
application or computer (machine.config) must have the
jitDebugging value set in the system.windows.forms section.
The application must also be compiled with debugging
enabled.
For example:
<configuration>
<system.windows.forms jitDebugging="true" />
</configuration>
When JIT debugging is enabled, any unhandled exception
will be sent to the JIT debugger registered on the computer
rather than be handled by this dialog box.
如何摆脱这个问题？我试图通过简单的方法db.savechanges()解决这个问题，但它不起作用。
答案 0 :(得分：9)
无法更新EntitySet，因为它具有DefiningQuery，并且元素中不存在支持当前操作的元素。
确保您的表格有主键！
如果没有添加主键并更新Entity Framework模型并再次运行。
答案 1 :(得分：0)
尝试使用此方法代替您的方法
Product_D obj= db.Product_D.FirtOrDefault(t => t.PCode == pCodeTextBox.Text);
if(obj==null){
obj=new Product_D();
db.Product_D.AddObject(obj);
}
obj.PCode = pCodeTextBox.Text;
obj.Name = nameTextBox.Text;
obj.Batch = batchTextBox.Text;
obj.Expiry = expiryTextBox.Text;
obj.Price = priceTextBox.Text;
db.SaveChanges();
答案 2 :(得分：0)
试试这个：
if(ModelState.IsValid)
{
db.SaveChanges();
}