时间戳

首页 > 解决方案 > 为什么实体框架会抛出无效的演员表

c# - 为什么实体框架会抛出无效的演员表

问题描述

无论我使用什么方法来查询数据，我都无法通过这种方法。它总是抛出一个错误：

指定的演员表无效。

不知道为什么这个在选角上会发疯。列定义为INT(10)MySQL 中的，模型是属性INT上的an，ID输入变量是 an INT，但仍然存在转换错误！使用几乎完全相同的逻辑来创建、删除和getAllCustomer方法工作正常。这是唯一的问题。

这是有问题的方法：

public static bool UpdateCustomerById(int id, string updatedName, int updatedAddressId)
{
        try
        {
            using (Context db = new Context())
            {
                Customer customer = (Customer)db.Find(typeof(Customer),id);
                //Customer customer = db.Customer.Find(id);
                customer.AddressId = updatedAddressId;
                customer.CustomerName = updatedName;
                db.SaveChanges();
            }

            return true;
        }
        catch (Exception err)
        {
            Console.WriteLine("Error: " + err);
            throw new Exception("Couldn't update the customer because: " + err);
        }
}

模型：

using System;
using System.Collections.Generic;

namespace Scheduler.Data.Models
{
    public partial class Customer
    {
        public int CustomerId { get; set; }
        public string CustomerName { get; set; }
        public int AddressId { get; set; }
        public sbyte Active { get; set; }
        public DateTime CreateDate { get; set; }
        public string CreatedBy { get; set; }
        public DateTime LastUpdate { get; set; }
        public string LastUpdateBy { get; set; }
    }
}

数据库表的 HTML 表表示 

<table border=1>
<tr>
<td bgcolor=silver class='medium'>Field</td>
<td bgcolor=silver class='medium'>Type</td>
<td bgcolor=silver class='medium'>Null</td>
<td bgcolor=silver class='medium'>Key</td>
<td bgcolor=silver class='medium'>Default</td>
<td bgcolor=silver class='medium'>Extra</td>
</tr>

<tr>
<td class='normal' valign='top'>customerId</td>
<td class='normal' valign='top'>int(10)</td>
<td class='normal' valign='top'>NO</td>
<td class='normal' valign='top'>PRI</td>
<td class='normal' valign='top'>NULL</td>
<td class='normal' valign='top'></td>
</tr>

<tr>
<td class='normal' valign='top'>customerName</td>
<td class='normal' valign='top'>varchar(45)</td>
<td class='normal' valign='top'>NO</td>
<td class='normal' valign='top'></td>
<td class='normal' valign='top'>NULL</td>
<td class='normal' valign='top'></td>
</tr>

<tr>
<td class='normal' valign='top'>addressId</td>
<td class='normal' valign='top'>int(10)</td>
<td class='normal' valign='top'>NO</td>
<td class='normal' valign='top'></td>
<td class='normal' valign='top'>NULL</td>
<td class='normal' valign='top'></td>
</tr>

<tr>
<td class='normal' valign='top'>active</td>
<td class='normal' valign='top'>tinyint(1)</td>
<td class='normal' valign='top'>NO</td>
<td class='normal' valign='top'></td>
<td class='normal' valign='top'>NULL</td>
<td class='normal' valign='top'></td>
</tr>

<tr>
<td class='normal' valign='top'>createDate</td>
<td class='normal' valign='top'>datetime</td>
<td class='normal' valign='top'>NO</td>
<td class='normal' valign='top'></td>
<td class='normal' valign='top'>NULL</td>
<td class='normal' valign='top'></td>
</tr>

<tr>
<td class='normal' valign='top'>createdBy</td>
<td class='normal' valign='top'>varchar(40)</td>
<td class='normal' valign='top'>NO</td>
<td class='normal' valign='top'></td>
<td class='normal' valign='top'>NULL</td>
<td class='normal' valign='top'></td>
</tr>

<tr>
<td class='normal' valign='top'>lastUpdate</td>
<td class='normal' valign='top'>timestamp</td>
<td class='normal' valign='top'>NO</td>
<td class='normal' valign='top'></td>
<td class='normal' valign='top'>CURRENT_TIMESTAMP</td>
<td class='normal' valign='top'>on update CURRENT_TIMESTAMP</td>
</tr>

<tr>
<td class='normal' valign='top'>lastUpdateBy</td>
<td class='normal' valign='top'>varchar(40)</td>
<td class='normal' valign='top'>NO</td>
<td class='normal' valign='top'></td>
<td class='normal' valign='top'>NULL</td>
<td class='normal' valign='top'></td>
</tr>
</table>

错误跟踪：

System.Exception
HResult=0x80131500
Message=couldn't update the customer because: System.InvalidCastException: Specified cast is not valid.
at MySql.Data.MySqlClient.MySqlDataReader.GetFieldValue[T](Int32 ordinal)
at lambda_method(Closure , DbDataReader )
at Microsoft.EntityFrameworkCore.Storage.Internal.TypedRelationalValueBufferFactory.Create(DbDataReader dataReader)
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.BufferlessMoveNext(DbContext _, Boolean
buffer)
at Pomelo.EntityFrameworkCore.MySql.Storage.Internal.MySqlExecutionStrategy.Execute[TState,TResult](TState state, Func`3
operation, Func`3 verifySucceeded)
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.MoveNext()
at System.Linq.Enumerable.First[TSource](IEnumerable`1 source)
at lambda_method(Closure )
at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ResultEnumerable`1.GetEnumerator()
at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.<_TrackEntities>d__17`2.MoveNext()
    at
Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.MoveNext()
at System.Linq.Enumerable.First[TSource](IEnumerable`1 source)
at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass15_1`1.<CompileQueryCore>
        b__0(QueryContext qc)
        at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
        at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
        at System.Linq.Queryable.First[TSource](IQueryable`1 source, Expression`1 predicate)
        at Scheduler.Data.CustomerDao.UpdateCustomerById(Int32 id, String updatedName, Int32 updatedAddressId)
        Source=Scheduler.Data
        StackTrace:
        at Scheduler.Data.CustomerDao.UpdateCustomerById(Int32 id, String updatedName, Int32 updatedAddressId) in
        C:\Users\source\repos\Scheduler\Scheduler.Data\CustomerDao.cs:line 79
        at Scheduler.Dashboard.ApplyChangesButton_Click(Object sender, EventArgs e) in
        C:\Users\source\repos\Scheduler\Scheduler\Dashboard.cs:line 112
        at System.Windows.Forms.Control.OnClick(EventArgs e)
        at System.Windows.Forms.Button.OnClick(EventArgs e)
        at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
        at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
        at System.Windows.Forms.Control.WndProc(Message& m)
        at System.Windows.Forms.ButtonBase.WndProc(Message& m)
        at System.Windows.Forms.Button.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.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr
        lparam)
        at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
        at
        System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr
        dwComponentID, Int32 reason, Int32 pvLoopData)
        at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext
        context)
        at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
        at System.Windows.Forms.Application.Run(Form mainForm)
        at Scheduler.Program.Main() in C:\Users\source\repos\Scheduler\Scheduler\Program.cs:line 19

关于为什么这种方法特别不起作用的任何想法或明显缺陷都会很好，谢谢

标签： c#.netentity-frameworkcastingentity-framework-core

解决方案

我发现这个问题的解决方案是将 tinyint(1) 更新为 tinyint(3)。更改以修复铸造错误，因为实体框架能够按照您的预期使用它。陷阱在CLI 中，默认情况下它使其成为 tinyint(1)，因此在事后将其更新为 tinyint(3) 应该可以修复它。

推荐阅读