Question

我有以下3个实体：

public class Event
{
    #region Fields

    private float cost;
    private DateTime dateEnd;
    private DateTime dateIni;
    private string description;
    private int disciplineId;
    private int id;
    private float latitude;
    private int limit;
    private string locationDescription;
    private string locationTitle;
    private float longitude;
    private int organizationId;
    private string presentationImg;
    private bool status;

    #endregion Fields

    #region Constructors

    public Event()
    {
        this.Sponsors =  new HashSet<EventOrganizations>();
        this.EventModes = new HashSet<EventModes>();
        this.Status = true;
    }

    #endregion Constructors

    #region Properties

    public float Cost
    {
        get { return cost; }
        set { cost = value; }
    }

    public DateTime DateEnd
    {
        get { return dateEnd; }
        set { dateEnd = value; }
    }

    public DateTime DateIni
    {
        get { return dateIni; }
        set { dateIni = value; }
    }

    public string Description
    {
        get { return description; }
        set { description = value; }
    }

    public virtual Discipline Discipline
    {
        get; set;
    }

    public int DisciplineId
    {
        get { return disciplineId; }
        set { disciplineId = value; }
    }

    public virtual ICollection<EventModes> EventModes
    {
        get;
        set;
    }

    public int Id
    {
        get { return id; }
        set { id = value; }
    }

    public float Latitude
    {
        get { return latitude; }
        set { latitude = value; }
    }

    public int Limit
    {
        get { return limit; }
        set { limit = value; }
    }

    public string LocationDescription
    {
        get { return locationDescription; }
        set { locationDescription = value; }
    }

    public string LocationTitle
    {
        get { return locationTitle; }
        set { locationTitle = value; }
    }

    public float Longitude
    {
        get { return longitude; }
        set { longitude = value; }
    }

    public virtual Organization Organization
    {
        get; set;
    }

    public int OrganizationId
    {
        get { return organizationId; }
        set { organizationId = value; }
    }

    public virtual Page Page
    {
        get; set;
    }

    public string PresentationImg
    {
        get { return presentationImg; }
        set { presentationImg = value; }
    }

    public virtual ICollection<EventOrganizations> Sponsors
    {
        get; set;
    }

    public bool Status
    {
        get { return status; }
        set { status = value; }
    }

    #endregion Properties
}

public class EventOrganizations
{
    #region Fields

    private int eventId;
    private int organizationId;

    #endregion Fields

    #region Properties

    public virtual Event Event
    {
        get; set;
    }

    public int EventId
    {
        get { return eventId; }
        set { eventId = value; }
    }

    public virtual Organization Organization
    {
        get; set;
    }

    public int OrganizationId
    {
        get { return organizationId; }
        set { organizationId = value; }
    }

    #endregion Properties
}

public class Organization
{
    #region Fields

    private string description;
    private int id;
    private string logo;
    private bool status;
    private string url;

    #endregion Fields

    #region Constructors

    public Organization()
    {
        this.Status = true;
        this.Events = new HashSet<Event>();
        this.EventSponsored = new HashSet<EventOrganizations>();
    }

    #endregion Constructors

    #region Properties

    [Required]
    [MaxLength(150)]
    public string Description
    {
        get { return description; }
        set { description = value; }
    }

    public virtual ICollection<Event> Events
    {
        get; set;
    }

    public virtual ICollection<EventOrganizations> EventSponsored
    {
        get; set;
    }

    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id
    {
        get { return id; }
        set { id = value; }
    }

    [Required]
    public string Logo
    {
        get { return logo; }
        set { logo = value; }
    }

    public bool Status
    {
        get { return status; }
        set { status = value; }
    }

    [MaxLength(150)]
    public string Url
    {
        get { return url; }
        set { url = value; }
    }

    #endregion Properties
}

上下文：

    modelBuilder.Entity<EventOrganizations>()
    .HasKey(i => new { i.EventId, i.OrganizationId });

    modelBuilder.Entity<EventOrganizations>()
            .HasRequired(i => i.Event)
            .WithMany(i => i.Sponsors)
            .HasForeignKey(i => i.EventId)
            .WillCascadeOnDelete(false);

    modelBuilder.Entity<EventOrganizations>()
            .HasRequired(i => i.Organization)
            .WithMany(i=>i.EventSponsored)
            .HasForeignKey(i => i.OrganizationId)
            .WillCascadeOnDelete(false);

现在在EventOrganizations表中我有：

    EventId OrganizationId
    7       6
    8       6
    9       6

假设我想对第（9,6）行执行更新操作，为此我要发送：

    {
      "Id": 9,
      "Sponsors": [{
          "EventId":9,
          "OrganizationId":8
        }]
      }

我的更新方法：

      public void Update(Event entity)
      {
      var existingEvent = context.Events
                                    .Include(x => x.EventModes)
                                    .Include(x => x.Sponsors)
                                    .Where(x => x.Id ==           entity.Id).FirstOrDefault<Event>();

      var addedSponsors = entity.Sponsors.Except(existingEvent.Sponsors, x => x.OrganizationId).ToList<EventOrganizations>();
      var deletedSponsors = existingEvent.Sponsors.Except(entity.Sponsors, x => x.OrganizationId).ToList<EventOrganizations>();
      deletedSponsors.ForEach(c => existingEvent.Sponsors.Remove(c));    
      foreach (EventOrganizations c in addedSponsors)
      {
        if (context.Entry(c).State == EntityState.Detached)
        {
            context.EventOrganizations.Attach(c);
        }
        existingEvent.Sponsors.Add(c);
      }

    context.SaveChanges();
   }

我不明白为什么只是执行删除而不是在EventOrganizations表上插入新的附加实体

Answer 1

由于“EventOrganizations”对象包含帖子上的Id，您应该使用

     foreach (EventOrganizations c in addedSponsors)
     {
         existingEvent.EventOrganizations.Add(c);
     }

问题在于，在ICollection中向子实体添加子项时，不应映射父ID。因此，您可以直接向表中添加赞助商，或者您可以从发布的数据中删除“EventId”值并将其添加到“赞助商”集合中。

更新多对多只删除不插入

1 个答案: