在尝试创建迁移时，您如何找到或知道“非拥有”实体类型在哪里？

Posted 2023-02-15

【中文标题】在尝试创建迁移时，您如何找到或知道“非拥有”实体类型在哪里？

【英文标题】：How do you find or know where the "non-owned" entity type when trying to create a migration?

【发布时间】：2021-10-12 17:27:33

【问题描述】：

我有以下课程：

拥有具有 CreditCardType 的 CreditCard 的求职者

 public class JobSeeker : Entity
 
     private readonly List<CreditCard> _creditCards;        
     public IEnumerable<CreditCard> CreditCards => _creditCards.AsReadOnly();
 

 public class CreditCard : Entity
 
     public CreditCardType CardType  get  return CreditCardType.From(_creditCardTypeID);  private set   
     private readonly int _creditCardTypeID;


 public class CreditCardType : Enumeration
 
     public static readonly CreditCardType Amex = new CreditCardType(1, nameof(Amex).ToLowerInvariant());

     public static readonly CreditCardType Visa = new CreditCardType(2, nameof(Visa).ToLowerInvariant());

     public static readonly CreditCardType MasterCard = new CreditCardType(3, nameof(MasterCard).ToLowerInvariant());

     public static IEnumerable<CreditCardType> List() => new[]  Amex, Visa, MasterCard ;

我的 DBContext 配置是：

class JobSeekerEntityTypeConfiguration : IEntityTypeConfiguration<JobSeeker>

    public void Configure(EntityTypeBuilder<JobSeeker> jsConfiguration)
    
        if (jsConfiguration == null)
        
            throw new ArgumentNullException(nameof(jsConfiguration));
        

        // Build the model
        jsConfiguration.OwnsOne(s => s.CompleteName);
        jsConfiguration.OwnsOne(s => s.HomeAddress);
        jsConfiguration.OwnsOne(s => s.BillingAddress);
        jsConfiguration.OwnsOne(s => s.EmAddress);
        jsConfiguration.OwnsOne(s => s.PersonalPhoneNumber);

        jsConfiguration.OwnsMany(a => a.CreditCards);

        //jsConfiguration.HasMany<CreditCard>().WithOne(JobSeeker).OnDelete(DeleteBehavior.Restrict);


        jsConfiguration.Property<DateTime>("CreatedDate");
        jsConfiguration.Property<DateTime>("UpdatedDate");
    


class CreditCardTypeEntityTypeConfiguration : IEntityTypeConfiguration<CreditCard>

    public void Configure(EntityTypeBuilder<CreditCard> ccConfiguration)
    
        if (ccConfiguration == null)
        
            throw new ArgumentNullException(nameof(ccConfiguration));
        

        // Build the model
        ccConfiguration.HasOne(o => o.CardType).WithMany().HasForeignKey("_creditCardTypeID");

        ccConfiguration.Property<DateTime>("CreatedDate");
        ccConfiguration.Property<DateTime>("UpdatedDate");

    


class CreditCardEntityTypeConfiguration : IEntityTypeConfiguration<CreditCardType>

    public void Configure(EntityTypeBuilder<CreditCardType> cctConfiguration)
    
        if (cctConfiguration == null)
        
            throw new ArgumentNullException(nameof(cctConfiguration));
        

        // Build the model
        cctConfiguration.ToTable("CreditCardTypes");

        cctConfiguration.HasKey(o => o.Id);

        cctConfiguration.Property(o => o.Id)
            .HasDefaultValue(1)
            .ValueGeneratedNever()
            .IsRequired();

        cctConfiguration.Property(o => o.Name)
            .HasMaxLength(200)
            .IsRequired();

        cctConfiguration.HasData(
                new  Id = 1, Name = "Amex" ,
                new  Id = 2, Name = "Visa" ,
                new  Id = 3, Name = "MasterCard" );


    

我的数据库上下文是：

public class JobSeekerContext : DbContext, IUnitOfWork

    private static readonly Type[] EnumerationTypes =  typeof(CreditCardType) ;

    public const string DEFAULT_SCHEMA = "jobseeker";

    private readonly ILoggerFactory MyConsoleLoggerFactory;

    private readonly IMediator Mediator;

    public DbSet<JobSeeker> JobSeekers  get; set; 

    public DbSet<CreditCard> CreditCards  get; set; 
    public DbSet<CreditCardType> CreditCardTypes  get; set; 

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    
        if (modelBuilder == null)
        
            throw new ArgumentNullException(nameof(modelBuilder));
        

        // Build the model
        modelBuilder.ApplyConfiguration(new CreditCardTypeEntityTypeConfiguration());
        modelBuilder.ApplyConfiguration(new CreditCardEntityTypeConfiguration());
        modelBuilder.ApplyConfiguration(new JobSeekerEntityTypeConfiguration());

当我运行迁移时，我收到以下错误：“无法将类型 'CreditCard' 标记为拥有，因为已经存在同名的非拥有实体类型。”

信用卡在哪里被标记为非所有？

【参考方案1】：

CreditCard 在哪里被标记为非所有？

在JobSeekerContext这里

public DbSet<CreditCard> CreditCards  get; set; 

这里

modelBuilder.ApplyConfiguration(new CreditCardTypeEntityTypeConfiguration());

以及整个（误导性命名的）CreditCardTypeEntityTypeConfiguration 类，因为它是 IEntityTypeConfiguration<CreditCard>。

---

Owned entity types 是特殊实体，仅通过所有者进行配置、查询和更新。

这是当前 EF Core 文档的By-design restrictions 部分的摘录：

您不能为自有类型创建 DbSet<T>。 您不能使用 ModelBuilder 上的自有类型调用 Entity<T>()。

请注意，应用IEnityTypeConfiguration<T> 类相当于在ModelBuilder 上调用Entity<T>()。

所以你打破了上述两个限制。

你需要做的是

从上下文中删除 DbSet<CreditCard> 属性 删除CreditCardTypeEntityTypeConfiguration类和对应的ApplyConfiguration调用 使用OwnsMany 方法提供/返回的构建器将CreditCard 配置代码移动到所有者JobSeeker 配置中。例如

jsConfiguration.OwnsMany(a => a.CreditCards, ccConfiguration =>

    // Build the model
    ccConfiguration.HasOne(o => o.CardType).WithMany().HasForeignKey("_creditCardTypeID");
    
    ccConfiguration.Property<DateTime>("CreatedDate");
    ccConfiguration.Property<DateTime>("UpdatedDate");
);