我每次运行应用程序时都会不断显示此错误消息。我正在使用实体 Framework 5: Code First

这是错误信息，

System.NotSupportedException: Model compatibility cannot be checked because the database does not contain model metadata. Model compatibility can only be checked for databases created using Code First or Code First Migrations.
   at System.Data.Entity.Internal.ModelCompatibilityChecker.CompatibleWithModel(InternalContext internalContext, ModelHashCalculator modelHashCalculator, Boolean throwIfNoMetadata)
   at System.Data.Entity.Internal.InternalContext.CompatibleWithModel(Boolean throwIfNoMetadata)
   at System.Data.Entity.Database.CompatibleWithModel(Boolean throwIfNoMetadata)
   at System.Data.Entity.DropCreateDatabaseIfModelChanges`1.InitializeDatabase(TContext context)
   at System.Data.Entity.Database.<>c__DisplayClass2`1.<SetInitializerInternal>b__0(DbContext c)
   at System.Data.Entity.Internal.InternalContext.<>c__DisplayClass8.<PerformDatabaseInitialization>b__6()
   at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)
   at System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization()
   at System.Data.Entity.Internal.LazyInternalContext.<InitializeDatabase>b__4(InternalContext c)
   at System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase()
   at System.Data.Entity.Internal.InternalContext.Initialize()
   at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType)
   at System.Data.Entity.Internal.Linq.InternalSet`1.Initialize()
   at System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext()
   at System.Data.Entity.Internal.Linq.InternalSet`1.ActOnSet(Action action, EntityState newState, Object entity, String methodName)
   at System.Data.Entity.Internal.Linq.InternalSet`1.Add(Object entity)
   at System.Data.Entity.DbSet`1.Add(TEntity entity)
   at LaundryService_DEMO.frmMain.btnCreate_Click(Object sender, EventArgs e) in d:\MyDocs\Visual Studio 2012\Projects\LaundryService_DEMO\LaundryService_DEMO\frmMain.cs:line 39

当我创建一个名为 invoice 的实体时，这个错误就开始了。这是实体的完整代码，

public class Invoice
{
    public string InvoiceID { get; set; }
    public string CustomerID { get; set; }
    public string UserID { get; set; }
    public decimal TotalAmount { get; set; }
    public DateTime TransactionDate { get; set; }
    public DateTime PaymentDate { get; set; }

    public Customer CustomerField { get; set; }
    public SystemUser SystemUserField { get; set; }
}

public class InvoiceMap : EntityTypeConfiguration<Invoice>
{
    public InvoiceMap()
    {
        // Primary Key
        this.HasKey(x => x.InvoiceID);

        // Property(ies) and Mapping(s)
        this.ToTable("Invoice");

        this.Property(x => x.InvoiceID)
            .IsRequired()
            .HasMaxLength(15)
            .HasColumnName("InvoiceID")
            .HasColumnType("nVarchar");

        this.Property(x => x.CustomerID)
            .IsRequired()
            .HasMaxLength(15)
            .HasColumnName("CustomerID")
            .HasColumnType("nVarchar");

        this.Property(x => x.UserID)
            .IsRequired()
            .HasMaxLength(15)
            .HasColumnName("UserID")
            .HasColumnType("nVarchar");

        this.Property(x => x.TotalAmount)
            .IsRequired()
            .HasColumnName("TotalAmount")
            .HasColumnType("decimal");

        this.Property(x => x.TransactionDate)
            .IsRequired()
            .HasColumnName("TransactionDate")
            .HasColumnType("datetime");

        this.Property(x => x.PaymentDate)
            .IsOptional()
            .HasColumnName("PaymentDate")
            .HasColumnType("datetime");

        // Relationship
        this.HasRequired(x => x.CustomerField)
            .WithMany(x => x.InvoiceCollection)
            .HasForeignKey(y => y.CustomerID);

        this.HasRequired(x => x.SystemUserField)
            .WithMany(x => x.InvoiceCollection)
            .HasForeignKey(y => y.UserID);
    }
}

为了复制应用程序，我包含了项目文件 available for download .所以这个问题不会充满代码。

如果问题中有我遗漏的细节，请发表评论，以便我将其包括在内。

最佳答案

我发现代码可以通过更改来工作

static LaundryShopContext()
{
  Database.SetInitializer<LaundryShopContext>(
    new DropCreateDatabaseIfModelChanges<LaundryShopContext>());
}

进入

static LaundryShopContext()
{
  Database.SetInitializer<LaundryShopContext>(
    new DropCreateDatabaseAlways<LaundryShopContext>());
}

关于c# - EF5 收到此错误消息 : Model compatibility cannot be checked because the database does not contain model metadata，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14064434/