Question

我是Entity框架的新手，我仍然在努力了解如何处理它。我碰到了一个奇怪的问题。我试图为一个＆＃34;一个＆gt;多个＆＃34;创建一个客户吸气剂。关系，但由于某种原因，它不起作用，因为我期待。

请查看以下代码：

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; }
}

本练习的重点是以某种方式告诉EF只提取未删除的电话号码e.t. ＆＃34; isDelete == false＆＃34;当我写UserInstance.Phones

时

我做错了什么？

Answer 1

下面的代码看起来就像是要躲避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; }
    }

我建议你离开并修改这一行（因为应该这样做，默认为EF）

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

稍后在您的代码中，当您实例化DbContext时，只需为IsDeleted添加此检查。如果您担心这一点，那对性能来说不是那么大的问题。无论如何，DbContext将在第一个缓存级别的内存中拥有DbSets的完整副本（大约告知）。

EF Code first - 自定义ICollection getter

1 个答案: