EF代码优先-自定义ICollection getter

Question

我是实体框架的新手，但我仍在尝试了解如何处理它。 我碰到一个奇怪的问题。 我正在尝试为“一对多”的关系创建一个客户获取器，但是由于某种原因，它无法正常工作。

请看下面的代码：

namespace DigitalCard.Data.Models
{
    using System;
    using System.Linq;
    using System.Collections.Generic;
    using System.ComponentModel.DataAnnotations;

    using Microsoft.AspNet.Identity.EntityFramework;

    using DigitalCard.Data.Commons.Interfaces;
    using DigitalCard.Data.Commons;
    using Microsoft.AspNet.Identity;
    using System.ComponentModel.DataAnnotations.Schema;

    public class User : BasicDbEntry, IUser, IBasicUser
    {
        public User(string userName, string firstName, string lastName) : this(userName)
        {
            this.UserName = userName;
            this.FirstName = firstName;
            this.LastName = lastName;
        }

        public virtual string PasswordHash { get; set; }

        //---> Table Attributes
        [Required]
        [Index("UserName", 1, IsUnique = true)]
        [MaxLength(100)]
        public string UserName { get; set; }

        [Required]
        [MaxLength(100)]
        public string FirstName { get; set; }

        [Required]
        [MaxLength(100)]
        public string LastName { get; set; }

        [Required]
        public int Age { get; set; }

        //---> Referances to other tables
        public virtual ICollection<Phone> _phones { get;  set; }

        [NotMapped]
        public virtual ICollection<Phone> Phones
        {
            get { return this._phones == null ? new List<Phone>() : this._phones.Where(a => a.IsDeleted == false).ToList<Phone>(); }
            set { this._phones = value; }
        }
    }
}

这是Phone类：

public class Phone : BasicContact
{
    public Phone() : base() { }

    // Table Attributes
    [Required]
    [IsPhoneNumber]
    public string Number { get; set; }

}


public class BasicContact : BasicDbEntry
{

    public BasicContact()
    {
    }

    // Table Attributes
    [Required(ErrorMessage = "Every type of contact should have a Label")]
    public string Label { get; set; }

    // Reference to other table
    public virtual User _user { get; private set; }

    [NotMapped]
    public virtual User User
    {
        get { return this._user; }
        set { this._user = value; }
    }
}


public class BasicDbEntry : IBasicDbEntry
{
    public BasicDbEntry() 
    {
        this.Id = Guid.NewGuid().ToString();
        this.CreatedOn = new DateTime(1900, 1, 1);
        this.DeletedOn = new DateTime(1900, 1, 1);
        this.ModifiedOn = new DateTime(1900, 1, 1);
    }

    [Key]
    [Required(ErrorMessage = "Every database item should have an Id")]
    public string Id { get; set; }
    public DateTime CreatedOn { get; set; }
    public DateTime ModifiedOn { get; set; }
    public bool IsDeleted { get; set; }
    public DateTime? DeletedOn { get; set; }
}

本练习的全部重点是，当我编写UserInstance.Phones时，以某种方式告诉EF仅拉出未删除的电话号码和“ isDelete == false ”

我究竟做错了什么？

Answer 1

下面的代码看起来像您要躲避EF。

    public virtual ICollection<Phone> _phones { get;  set; }

    [NotMapped]
    public virtual ICollection<Phone> Phones
    {
        get { return this._phones == null ? new List<Phone>() : this._phones.Where(a => a.IsDeleted == false).ToList<Phone>(); }
        set { this._phones = value; }
    }

我建议您只保留并修改此行（因为应该这样做，默认情况下为EF）

    public virtual ICollection<Phone> Phones { get;  set; }

稍后在代码中，实例化DbContext时，只需为IsDeleted添加此检查即可。 如果您担心的话，这对性能而言并不是什么大问题。 无论如何，DbContext将在第一个缓存级别（近似地告诉）在内存中具有DbSet的完整副本。