Question

用最简单的术语来说，当我尝试从POST数据更新我的对象Activities时，关系Activities.Contacts的现有多对多连接数据不会从MSSQL中删除SaveChanges期间的数据库。如果该活动的POST数据中的某个联系人已存在，则会导致错误。

违反PRIMARY KEY约束＆＃39; PK_tblActionContact＆＃39;。无法在对象＆＃39; dbo.tblActionContact＆＃39;中插入重复键。重复键值为（1,94）

我的控制器：

    public ActionResult Edit(Activity activity)
    {
        if (ModelState.IsValid)
        {
            //save the activity
            activity.Contact.Clear(); //Clear the existing contacts
            db.Entry(activity).State = EntityState.Modified;

            //then add each contact
            foreach (int contactId in activity.SelectedContactIds)
            {
                activity.Contact.Add(db.tblContact.Find(contactId));
            }

            db.SaveChanges();
            TempData["Flash Success"] = "Activity Saved";
            return RedirectToAction("Index", "Home");
        }

        return View(activity);
    }

我已经尝试了很多不同的变化，基于对这个好网站的大量搜索，但我发现没有什么可行的。

我对activity.Contact.Clear()抱有很高的期望，这确实清除了对象中活动的现有联系人，但它并没有从实际的MSSQL表中清除它们。

如果我选择的是未在现有Activity中选择的新颖联系人，那么它会保存得很好，当然包括在创建新Activity时。

拜托，我是新来发布的，所以如果需要更多代码或信息，请告诉我们！

修改我发布了我的背景和适用的模型：

上下文：

public partial class SalesEntities : DbContext
{
    public SalesEntities()
        : base("name=SalesEntities")
    {
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        throw new UnintentionalCodeFirstException();
    }

    public virtual DbSet<SalesAccount> tblAccount { get; set; }
    public virtual DbSet<Activity> tblAction { get; set; }
    public virtual DbSet<ActionTypeLookup> tblActionTypeLookup { get; set; }
    public virtual DbSet<Campaign> tblCampaign { get; set; }
    public virtual DbSet<Contact> tblContact { get; set; }
    public virtual DbSet<GenericLookup> tblGenericLookup { get; set; }
    public virtual DbSet<MarketingLetter> tblMarketingLetter { get; set; }
    public virtual DbSet<Opportunity> tblOpportunity { get; set; }
    public virtual DbSet<Product> tblProduct { get; set; }
    public virtual DbSet<Source> tblSource { get; set; }
    public virtual DbSet<VerifiedAccount> tblVerifiedAccount { get; set; }
    public virtual DbSet<AspNetUsers> AspNetUsers { get; set; }
}
}

活动模型：

namespace SalesTracker.Models
{
using System;
using System.Collections.Generic;

public partial class Activity
{
    public Activity()
    {
        this.Contact = new HashSet<Contact>();
    }

    public int ActionId { get; set; }
    public int AccountId { get; set; }
    public int CampaignId { get; set; }
    public string SalespersonId { get; set; }
    public int ActionTypeId { get; set; }
    public string Note { get; set; }
    public Nullable<System.DateTime> ActionDate { get; set; }
    public string NextStep { get; set; }
    public string Duration { get; set; }
    public Nullable<int> MarketingLetterId { get; set; }
    public string EditedBy { get; set; }
    public bool Active { get; set; }
    public System.DateTime EditDate { get; set; }
    public bool Completed { get; set; }

    public virtual SalesAccount SalesAccount { get; set; }
    public virtual ActionTypeLookup ActionTypeLookup { get; set; }
    public virtual Campaign Campaign { get; set; }
    public virtual MarketingLetter MarketingLetter { get; set; }
    public virtual ICollection<Contact> Contact { get; set; }
    public virtual AspNetUsers AspNetUsers { get; set; }
    public virtual AspNetUsers AspNetUsersEditedBy { get; set; }
}
}

和联系模式

namespace SalesTracker.Models
{
using System;
using System.Collections.Generic;

public partial class Contact
{
    public Contact()
    {
        this.Activity = new HashSet<Activity>();
    }

    public int ContactId { get; set; }
    public int AccountId { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Title { get; set; }
    public string Phone { get; set; }
    public string Email { get; set; }
    public string Note { get; set; }
    public System.DateTime VerifiedDate { get; set; }
    public string VerifiedBy { get; set; }
    public int VerificationStatus { get; set; }
    public System.DateTime EditDate { get; set; }
    public string EditedBy { get; set; }
    public bool Active { get; set; }

    public virtual SalesAccount SalesAccount { get; set; }
    public virtual ICollection<Activity> Activity { get; set; }
    }
}

Answer 1

我认为你对Clear()的目的感到困惑。它所做的就是删除父项及其子项之间的引用，它实际上并没有删除实体。您将需要执行以下操作以实际删除它们：

activity.Contact.ToList().ForEach(c => db.Contact.DeleteObject(c));

当然遵循db.SaveChanges();

连接表中的现有行在多对多更新期间未被清除

1 个答案: