Question

有人请让我摆脱困境，让我知道自己做过的/没做过的使我的代码失败的事情吗？

我首先使用Entity Framework数据库。当我查询一个实体并请求包含一个相关实体时，出现以下错误：无效的列名“ PrimaryContact_ContactID”。调用Load方法的行上会抛出异常。

我正在尝试查询Enterprise实体之一，并使其也包含Company实体。

（这是复制异常的简化示例）

这是我的实体类：

//Enterprise
public class Enterprise
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int CompanyID { get; set; }

    public virtual Company Company { get; set; }
}

//Company
public class Company
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int PrimaryContactId { get; set; }

    public virtual CompanyContact PrimaryContact { get; set; }
}

//CompanyContact class
public class CompanyContact
{
    public int ContactID { get; set; }
    public string Name { get; set; }
}

这是DataContext类

public class DataContext : DbContext
{
    public DbSet<Enterprise> Enterprises { get; set; }
    public DbSet<Company> Companies { get; set; }
    public DbSet<CompanyContact> CompanyContacts { get; set; }

    public DataContext(string connStrName = nameof(DataContext)) : base($"Name={connStrName}")
    {
        Database.SetInitializer<DataContext>(null);
        base.Configuration.ProxyCreationEnabled = false;
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();

        modelBuilder.Entity<Enterprise>().HasKey(pk => pk.Id);
        modelBuilder.Entity<Enterprise>().Property(i => i.Id)
                                         .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

        modelBuilder.Entity<Company>().HasKey(pk => pk.Id);
        modelBuilder.Entity<Company>().Property(i => i.Id)
                                      .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
        modelBuilder.Entity<Company>().HasOptional(t => t.PrimaryContact);

        modelBuilder.Entity<CompanyContact>().HasKey(pk => pk.ContactID);
        modelBuilder.Entity<CompanyContact>().Property(i => i.ContactID)
                                             .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

    }
}

这是Main方法，我在其中调用代码。

    static void Main(string[] args)
    {
        try
        {
            using (var ctx = new DataContext())
            {
                ctx.Database.Log = Console.Write;

                var ent = ctx.Enterprises.FirstOrDefault(e => e.Id == 1);

                //Exception thrown on this line.
                ctx.Entry(ent).Reference(e => e.Company).Load();

                Console.WriteLine(ent);
                Console.WriteLine(ent.Company);
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e);
        }

        Console.ReadLine();
    }

我打开了EF日志记录，这是运行代码的输出（为简短起见，我没有包括完整的堆栈跟踪信息）：

Opened connection at 2/22/2019 3:43:02 PM -06:00
SELECT TOP (1)
    [Extent1].[Id] AS [Id],
    [Extent1].[Name] AS [Name],
    [Extent1].[CompanyID] AS [CompanyID]
    FROM [dbo].[Enterprise] AS [Extent1]
    WHERE 1 = [Extent1].[Id]
-- Executing at 2/22/2019 3:43:02 PM -06:00
-- Completed in 85 ms with result: SqlDataReader

Closed connection at 2/22/2019 3:43:02 PM -06:00
Opened connection at 2/22/2019 3:43:02 PM -06:00
SELECT
    [Extent1].[Id] AS [Id],
    [Extent1].[Name] AS [Name],
    [Extent1].[PrimaryContactID] AS [PrimaryContactID],
    [Extent1].[PrimaryContact_ContactID] AS [PrimaryContact_ContactID]
    FROM [dbo].[Company] AS [Extent1]
    WHERE [Extent1].[Id] = @EntityKeyValue1
-- EntityKeyValue1: '1' (Type = Int32, IsNullable = false)
-- Executing at 2/22/2019 3:43:02 PM -06:00
-- Failed in 68 ms with error: Invalid column name 'PrimaryContact_ContactID'.

Closed connection at 2/22/2019 3:43:02 PM -06:00
System.Data.Entity.Core.EntityCommandExecutionException: An error occurred while executing the command definition. See the inner exception for details. ---> System.Data.SqlClient.SqlException: Invalid column name 'PrimaryContact_ContactID'.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrap

最后，这是数据库架构图：

我确定我必须缺少一些基本知识，但是经过大量搜索之后，我仍无法解决问题。

Answer 1

您需要对不遵循EF默认约定的导航属性强制使用[ForeignKey]属性：

public class Company
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int PrimaryContactId { get; set; }

    [ForeignKey(nameof(PrimaryContactId))]
    public virtual CompanyContact PrimaryContact { get; set; }
}

否则，EF不会将您的PrimaryContactId属性识别为PrimaryContact的列，它将创建另一个列PrimaryContact_ContactID。

Answer 2

我遇到了同样的错误，并在我的命名约定中寻找解决方案。我尝试了所有可能的约定和技巧，只是为了找出问题的原因。

我错误地初始化了数据库。我需要一个用于SQLite的初始化程序（示例用法）。这是我的CustomContext中的“ OnModelCreating”方法的工作示例。

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
{   
    var dbi = new SqliteDropCreateDatabaseWhenModelChanges<LogsContext>(modelBuilder);
    DB.SetInitializer<LogsContext>(dbi);
    base.OnModelCreating(modelBuilder);
}

我希望这样可以在查找错误的过程中为某人节省一些时间。

取得SQL错误：无效的栏名称'PrimaryContact_ContactID'

2 个答案: