EF Code First：如何从 nuget 包控制台查看“EntityValidationErrors”属性？

Question

我对此感到茫然：

我已经为实体框架 (4.1.3) 代码优先方法定义了我的类。一切都很好（我正在创建表格等），直到我开始播种。

现在我做的时候

Add-Migration "remigrate" ; Update-Database;

我在包控制台上收到错误消息“一个或多个实体的验证失败。有关更多详细信息，请参阅 'EntityValidationErrors' 属性。”

我的 Seed() 方法中有一个断点，但是因为我在项目未运行时在控制台上运行它，所以我不知道如何获取详细信息（PS - 我已经看过线程Validation failed for one or more entities while saving changes to SQL Server Database using Entity Framework 显示了我如何查看该属性。）

我知道我的 Seed() 方法有问题，因为如果我在方法调用之后立即返回，错误就会消失。那么如何设置断点以便查看验证错误是什么？有点输了还是有其他方法可以在 nuget 控制台中跟踪它？？

Answer 1

I Also had same model validation problem but successfully catch by myself after lot of thinking;

I use reverse engineering method to catch the problem out of Over 80 + Model Classes;

1> Made copy of dbcontext, changing the name (I add "1" at end and make respective changes in class constructor and initialization etc.

Old:
 
>public class AppDb : IdentityDbContext<ApplicationUser>
>     
> {
> public AppDb(): base("DefaultConnection", throwIfV1Schema: false)
> {
> 
> }
>     
> public static AppDb Create()
>{
>return new AppDb();
>} 

**New:**

>public class AppDb1 : IdentityDbContext<ApplicationUser>
>{
>public AppDb1()
>: base("DefaultConnection", throwIfV1Schema: false)
>{
>}
> 
>public static AppDb1 Create()
> {
> return new AppDb1();
>  }`

...
2> Make changes to Codefirst Migration Configuration from Old DbContext to my new Context.

> internal sealed class Configuration :
> DbMigrationsConfiguration<DAL.AppDb1> { public Configuration() {
> AutomaticMigrationsEnabled = false; }    protected override void
> Seed(DAL.AppDb1 context) {`

3> Comment the Dbsets in new DbContext which was doubt.
4> Apply update migration if succeeded the probelm lye in Commented section.
5> if not then commented section is clear of bug clear.
6> repeat the (4) until found the right place of bug.
7> Happy Codding

Answer 2

已经使用部分类定义扩展您的 DBContext 类！

如果您查看 DbContext 的类定义，它将类似于以下内容：

// DatabaseContext.cs   -- This file is auto generated and thus shouldn't be changed. 
public partial class [DatabaseContextName] : DbContext { ... }

因此，您可以在另一个文件中创建相同的定义并覆盖您想要的部分。

// partialDatabaseContext.cs  -- you can safely make changes 
// that will not be overwritten in here.
public partial class [DatabaseContextName] : DbContext { // Override defaults here } 

部分类的整个想法--您是否注意到 DbContext 是部分类-- 是您可以扩展已生成的类（或组织类到多个文件中），在我们的例子中，我们还希望从添加到 DbContext 的部分类中覆盖 SaveChanges 方法。

这样，我们可以从所有现有的 DbContext/SaveChanges 调用中获取错误调试信息，而无需更改您的种子代码或开发代码。

这就是我要做的（注意不同的是，我只是在我们自己编写的 DbContext 部分类中重写 SaveChanges 方法，不是生成的）。另外，请确保您的部分类使用了正确的命名空间，否则您会碰壁。

public partial class Database : DbContext
{
    public override int SaveChanges()
    {
        try
        {
            return base.SaveChanges();
        }
        catch (DbEntityValidationException ex)
        {
            var sb = new StringBuilder();

            foreach (var failure in ex.EntityValidationErrors)
            {
                sb.AppendFormat("{0} failed validation\n", failure.Entry.Entity.GetType());
                foreach (var error in failure.ValidationErrors)
                {
                    sb.AppendFormat("- {0} : {1}", error.PropertyName, error.ErrorMessage);
                    sb.AppendLine();
                }
            }

            throw new DbEntityValidationException(
                "Entity Validation Failed - errors follow:\n" +
                sb.ToString(), ex
                ); // Add the original exception as the innerException
        }
    }
}

Answer 3

我将理查兹的答案转换为扩展方法：

  public static int SaveChangesWithErrors(this DbContext context)
    {
        try
        {
            return context.SaveChanges();
        }
        catch (DbEntityValidationException ex)
        {
            StringBuilder sb = new StringBuilder();

            foreach (var failure in ex.EntityValidationErrors)
            {
                sb.AppendFormat("{0} failed validation\n", failure.Entry.Entity.GetType());
                foreach (var error in failure.ValidationErrors)
                {
                    sb.AppendFormat("- {0} : {1}", error.PropertyName, error.ErrorMessage);
                    sb.AppendLine();
                }
            }

            throw new DbEntityValidationException(
                "Entity Validation Failed - errors follow:\n" +
                sb.ToString(), ex
            ); // Add the original exception as the innerException
        }
    }

这样调用：

context.SaveChangesWithErrors();

Answer 4

我最近也被这个惹恼了。我通过在 Seed 方法的 Configuration 类中放置一个包装函数来修复它，并将对 SaveChanges 的调用替换为对我的函数的调用。此函数将简单地枚举 EntityValidationErrors 集合中的错误，并在 Exception 消息列出各个问题时重新引发异常。这会使输出显示在 NuGet 包管理器控制台中。

代码如下：

/// <summary>
/// Wrapper for SaveChanges adding the Validation Messages to the generated exception
/// </summary>
/// <param name="context">The context.</param>
private void SaveChanges(DbContext context) {
    try {
        context.SaveChanges();
    } catch (DbEntityValidationException ex) {
        StringBuilder sb = new StringBuilder();

        foreach (var failure in ex.EntityValidationErrors) {
            sb.AppendFormat("{0} failed validation\n", failure.Entry.Entity.GetType());
            foreach (var error in failure.ValidationErrors) {
                sb.AppendFormat("- {0} : {1}", error.PropertyName, error.ErrorMessage);
                sb.AppendLine();
            }
        }

        throw new DbEntityValidationException(
            "Entity Validation Failed - errors follow:\n" + 
            sb.ToString(), ex
        ); // Add the original exception as the innerException
    }
}

只需在种子方法中用SaveChanges(context) 替换对context.SaveChanges() 的调用即可。

Answer 5

我将 craigvl 的版本转换为 C# 我必须添加 context.SaveChanges();为了让它为我工作，如下所示。

try
{
    byte[] bytes = System.IO.File.ReadAllBytes(@"C:\Users\sheph_000\Desktop\Rawr.png");
    Console.WriteLine(bytes);

    context.BeverageTypes.AddOrUpdate(
        x => x.Name,
        new AATPos.DAL.Entities.BeverageType { ID = 1, Name = "Sodas" }
        );

    context.Beverages.AddOrUpdate(
        x => x.Name,
        new AATPos.DAL.Entities.Beverage { ID = 1, Name = "Coke", BeverageTypeID = 1, ImageData = bytes, IsStocked = true, StockLevel = 10, Price = 10.00M, ImageMimeType = "test" },
        new AATPos.DAL.Entities.Beverage { ID = 2, Name = "Fanta", BeverageTypeID = 1, ImageData = bytes, IsStocked = true, StockLevel = 10, Price = 10.00M, ImageMimeType = "test" },
        new AATPos.DAL.Entities.Beverage { ID = 3, Name = "Sprite", BeverageTypeID = 1, ImageData = bytes, IsStocked = true, StockLevel = 10, Price = 10.00M, ImageMimeType = "test" },
        new AATPos.DAL.Entities.Beverage { ID = 4, Name = "Cream Soda", BeverageTypeID = 1, ImageData = bytes, IsStocked = true, StockLevel = 10, Price = 10.00M, ImageMimeType = "test" },
        new AATPos.DAL.Entities.Beverage { ID = 5, Name = "Pepsi", BeverageTypeID = 1, ImageData = bytes, IsStocked = true, StockLevel = 10, Price = 10.00M, ImageMimeType = "test" }
        );

    context.SaveChanges();
}
catch (System.Data.Entity.Validation.DbEntityValidationException ex)
{
    var sb = new System.Text.StringBuilder();
    foreach (var failure in ex.EntityValidationErrors)
            {
                sb.AppendFormat("{0} failed validation", failure.Entry.Entity.GetType());
        foreach (var error in failure.ValidationErrors)
                {
            sb.AppendFormat("- {0} : {1}", error.PropertyName, error.ErrorMessage);
            sb.AppendLine();
                }
            }

    throw new Exception(sb.ToString());
}

Answer 6

Richard 感谢您让我走上了正确的道路（遇到了同样的问题），下面是一个没有包装器的替代方案，这在迁移配置种子方法中对我有用：

 Protected Overrides Sub Seed(context As NotificationContext)

        Try
            context.System.AddOrUpdate(
               Function(c) c.SystemName,
                New E_NotificationSystem() With {.SystemName = "System1"},
                New E_NotificationSystem() With {.SystemName = "System2"},
                New E_NotificationSystem() With {.SystemName = "System3"})

            context.SaveChanges()

        Catch ex As DbEntityValidationException

            Dim sb As New StringBuilder

            For Each failure In ex.EntityValidationErrors

                sb.AppendFormat("{0} failed validation" & vbLf, failure.Entry.Entity.[GetType]())

                For Each [error] In failure.ValidationErrors
                    sb.AppendFormat("- {0} : {1}", [error].PropertyName, [error].ErrorMessage)
                    sb.AppendLine()
                Next
            Next

            Throw New Exception(sb.ToString())

        End Try
End Sub

然后能够在包管理器控制台中看到异常。希望这对某人有所帮助。