EF 代码首先没有 return 实体的相关关系

Question

我正在使用代码优先和存储库模式

实体：

   public class Company : BaseEntity
    {
        private ICollection<CompanyRole> _companyRoles;

        private ICollection<Branch> _branches;

        public string Name { get; set; }

        public int CityId { get; set; }

        public virtual ICollection<CompanyRole> CompanyRoles
        {
            get { return _companyRoles ?? (_companyRoles = new List<CompanyRole>()); }
            protected set { _companyRoles = value; }
        }

        public virtual ICollection<Branch> Branches
        {
            get { return _branches ?? (_branches = new List<Branch>()); }
            protected set { _branches = value; }
        }

        public virtual City City { get; set; }
    }

FluentApi 映射：

    public class CompanyConfiguration : EntityTypeConfiguration<Company>
    {
        public CompanyConfiguration()
        {
            this.ToTable("Company");
            this.HasKey(c => c.Id);
            this.Property(c => c.Name).HasMaxLength(100).IsRequired();

            this.HasRequired(c => c.City)
             .WithMany()
             .HasForeignKey(c => c.CityId)
             .WillCascadeOnDelete(false);      

            this.HasMany(v => v.CompanyRoles)
            .WithMany()
            .Map(m => m.ToTable("Company_CompanyRole_Mapping")); 
        }
    }

    public class BranchConfiguration : EntityTypeConfiguration<Branch>
    {
        public BranchConfiguration()
        {
            this.ToTable("Branch");
            this.HasKey(c => c.Id);
            this.Property(c => c.Name).HasMaxLength(100).IsRequired();
            this.HasRequired(c => c.Company)
            .WithMany()
            .HasForeignKey(c => c.CompanyId);
        }
    }

存储库：

    public class EFRepository<T> : IRepository<T> where T : class
    {
        public EFRepository(DbContext dbContext)
        {
            if (dbContext == null)
                throw new ArgumentNullException("dbContext");
            DbContext = dbContext;
            DbSet = DbContext.Set<T>();
        }

        protected DbContext DbContext { get; set; }

        protected DbSet<T> DbSet { get; set; }

        public virtual IQueryable<T> GetAll()
        {
            return DbSet;
        }

        public virtual T GetById(int id)
        {
            return DbSet.Find(id);
        }

    }

当我使用 GetById 方法时，它 return 是我的公司，但 CompanyRoles、Branches 和 City 为空（但 CityId 有值）。预计 GetById 方法将 return 具有相关关系的实体。

Answer 1

我在我的项目中使用类似的模式。当我创建存储库时，我需要扩展我喜欢的通用存储库的任何方法：

    public class CompanyRepository : EFRepository<Company>, ICompanyRepository

然后实现方法GetCompany

  public Company GetCompany(int id)
    {
        return this.DbContext.Set<Company>()
           .Include(a => a.CompanyRoles)
           .Include(a => a.Branches)
           .SingleOrDefault(a => a.Id == id);}

其他方法是在收到实体后手动加载集合：

public Company GetCompany(int id)
    {
        var company =  this.GetById(id);
        this.DbContext.Entry(company).Collection(a => a.CompanyRoles).Load();
        this.DbContext.Entry(company).Collection(a => a.Branches).Load();
        return company;
}

EF 代码首先没有 return 实体的相关关系

EF code first does not return related relationship for entity

entity-framework

ef-code-first