asp.net-mvc - 包含文件的 ASP.NET MVC 模型

Question

您好，我正在尝试添加一个可以将文件存储到现有 ASP.NET MVC Code First 项目的模型。

namespace MyMVCApp.Models
{
  public class FileUpload
  {
    [Key]
    public int ID { get; set; }
    public string FileName { get; set; }
    public string FilePath { get; set; }

    [Required]
    public HttpPostedFileBase File { get; set; }
  }
}

我已将以下内容添加到项目的 DbContext 文件中:

public DbSet<FileUpload> FileUploads { get; set; }

我正在尝试使用包管理器控制台中的 Entity Framework 迁移将表添加到现有数据库:

PM> Add-Migration FileUpload

运行 ubove 命令时出现以下错误:

System.Data.Entity.ModelConfiguration.ModelValidationException: One or more validation errors were detected during model generation:

\tSystem.Data.Entity.Edm.EdmEntityType: : EntityType 'HttpPostedFileBase' has no key defined. Define the key for this EntityType.
\tSystem.Data.Entity.Edm.EdmEntitySet: EntityType: EntitySet 'HttpPostedFileBases' is based on type 'HttpPostedFileBase' that has no keys defined.

   at System.Data.Entity.ModelConfiguration.Edm.EdmModelExtensions.ValidateAndSerializeCsdl(EdmModel model, XmlWriter writer)
   at System.Data.Entity.DbModelBuilder.Build(DbProviderManifest providerManifest, DbProviderInfo providerInfo)
   at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)

   at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
   at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.LazyInternalContext.get_CodeFirstModel()
   at System.Data.Entity.Infrastructure.EdmxWriter.WriteEdmx(DbContext context, XmlWriter writer)
   at System.Data.Entity.Migrations.Extensions.DbContextExtensions.<>c__DisplayClass1.<GetModel>b__0(XmlWriter w)
   at System.Data.Entity.Migrations.Extensions.DbContextExtensions.GetModel(Action`1 writeXml)
   at System.Data.Entity.Migrations.Extensions.DbContextExtensions.GetModel(DbContext context)
   at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration, DbContext usersContext)
   at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration)
   at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.GetMigrator()
   at System.Data.Entity.Migrations.Design.ToolingFacade.GetPendingMigrationsRunner.RunCore()
   at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run()
One or more validation errors were detected during model generation:

\tSystem.Data.Entity.Edm.EdmEntityType: : EntityType 'HttpPostedFileBase' has no key defined. Define the key for this EntityType.
\tSystem.Data.Entity.Edm.EdmEntitySet: EntityType: EntitySet 'HttpPostedFileBases' is based on type 'HttpPostedFileBase' that has no keys defined.

我错过了什么？

Answer 1

您无法使用 Entity Framework 持久保存任意 .NET 类。

为了使 Entity Framework 能够持久化它们，类必须满足几个要求，例如错误中调用的要求(未定义键)

确实，您应该尝试仅保留原始类型(int、string 等)和您自己设计的类。

在这种情况下，正确的类型是byte[]

这意味着您需要排除模型上存在 HttpPostedFileBase 属性的情况。

相反，请考虑使用字节数组来存储数据和另一个属性，例如存储文件类型/名称的字符串