Question

我对EF代码优先有疑问。

我创建了两个POCO类和相应的映射类

public partial class Country
{
    public Country()
    {
        this.Employees = new HashSet<Employee>();
        this.States = new HashSet<State>();
    }

    public int CountryId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public Nullable<bool> Status { get; set; }

    public virtual ICollection<Employee> Employees { get; set; }
    public virtual ICollection<State> States { get; set; }
}

internal partial class Country_Mapping : EntityTypeConfiguration<Country>
{
    public Country_Mapping()
    {                        
          this.HasKey(t => t.CountryId);        
          this.ToTable("Country");
          this.Property(t => t.CountryId).HasColumnName("CountryId");
          this.Property(t => t.Name).HasColumnName("Name").IsUnicode(false).HasMaxLength(100);
          this.Property(t => t.Description).HasColumnName("Description").IsUnicode(false).HasMaxLength(200);
          this.Property(t => t.Status).HasColumnName("Status");
     }
}

public partial class State
{
    public State()
    {
        this.Employees = new HashSet<Employee>();
    }

    public int StateId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public Nullable<int> CountryId { get; set; }
    public Nullable<bool> Status { get; set; }

    public virtual Country Country { get; set; }
    public virtual ICollection<Employee> Employees { get; set; }
}

internal partial class State_Mapping : EntityTypeConfiguration<State>
{
    public State_Mapping()
    {                        
          this.HasKey(t => t.StateId);        
          this.ToTable("State");
          this.Property(t => t.StateId).HasColumnName("StateId");
          this.Property(t => t.Name).HasColumnName("Name").IsUnicode(false).HasMaxLength(100);
          this.Property(t => t.Description).HasColumnName("Description").IsUnicode(false).HasMaxLength(200);
          this.Property(t => t.CountryId).HasColumnName("CountryId");
          this.Property(t => t.Status).HasColumnName("Status");
          this.HasOptional(t => t.Country).WithMany(t => t.States).HasForeignKey(d => d.CountryId);
     }
}

在Country和State课程中，Country与State之间没有导航关系。但现在我想使用Include实体框架声明来获取该国家的所有州。

UnityOfWork work = new UnityOfWork(new DbContextFactory<eSMSDbContext>());
var countryColl = work.GetRepository<Country>().Table.Include("State");

如何通过国家/地区获取州信息？

Answer 1

如果没有从Country类到State类的导航属性，则Country对象没有任何变量来保存State表的内容。实体框架只能将SQL信息映射到C＃对象（如果存在）。

如果没有添加导航属性，您需要一个单独的变量（可能List<State)）来保存State个对象，不幸的是，您需要一个单独的Entity Framework调用来查找这些值，像

List<State> states = work.GetRepository<State>().Where(s => s.CountryId == countryId);

这有一个明显的缺点，即与Country对象成为一个单独的对象，并且没有嵌套（List<Country>无法保存与每个对应的List<State>

EF CF - 获取没有外键关系的子表信息

1 个答案: