实体框架插入新行而不是更新它们

问题描述

将数据更新到数据库时出现问题.当我要更新数据时，Entitiy Framework将新行添加到可以具有多行的表(具有外键的表)中.

I have a problem when I am updating data to database. When I want to update data, Entitiy Framework adds new rows to tables that can have multiple rows (tables that have foreign key).

数据库模型:

当我更新电话/联系人"或标签"实体时，实体框架会自动添加新行，而不是对其进行更新

When I update Phone/Contact or Tags entity, Entity Framework automatically adds new row instead of updating it

这是我使用的代码:

public string UpdateContact(Contact contact)
{
    if (contact != null)
    {

        int id = Convert.ToInt32(contact.id);
        Contact Updatecontact = db.Contacts.Where(a => a.id == id).FirstOrDefault();
        Updatecontact.firstname = contact.firstname;
        Updatecontact.lastname = contact.lastname;
        Updatecontact.address = contact.address;
        Updatecontact.bookmarked = contact.bookmarked;
        Updatecontact.city = contact.city;
        Updatecontact.notes = contact.notes;
        Updatecontact.Emails1 = contact.Emails1;
        Updatecontact.Phones1 = contact.Phones1;
        Updatecontact.Tags1 = contact.Tags1;
        db.SaveChanges();
        return "Contact Updated";

    }
    else
    {
        return "Invalid Record";
    }
}

这是EF模型代码:

联系方式:

public partial class Contact
{
    public Contact()
    {
        this.Emails1 = new HashSet<Email>();
        this.Phones1 = new HashSet<Phone>();
        this.Tags1 = new HashSet<Tag>();
    }

    public int id { get; set; }
    public string firstname { get; set; }
    public string lastname { get; set; }
    public string address { get; set; }
    public string city { get; set; }
    public Nullable<byte> bookmarked { get; set; }
    public string notes { get; set; }

    public virtual ICollection<Email> Emails1 { get; set; }
    public virtual ICollection<Phone> Phones1 { get; set; }
    public virtual ICollection<Tag> Tags1 { get; set; }
}

电子邮件/标签和电话的型号相同(值的名称不同)

Emails/Tags and Phone have same model (with different name for value)

public partial class Email
{
        public int id { get; set; }
        public int id_contact { get; set; }
        public string email1 { get; set; }

        public virtual Contact Contact1 { get; set; }
}

推荐答案

更新属性，而不是设置新对象.

Update properties rather than set new objects.

  Updatecontact.Emails1.email1 = contact.Emails1.email1;
  Updatecontact.Phones1.number = contact.Phones1.number;
  Updatecontact.Tags1.tag1 = contact.Tags1.tag1;

您的联系人模型似乎具有列表，其中包含电子邮件，电话和标签.如果是这样，则简单的分配将不起作用.相反，当从客户端发送时，您必须一个一个地查找并更新:

seems that your contact model has lists of emails, phones and tags. If this is so, then simple assignment won't work. Instead, when sent from the client, you have to find one-by-one and update:

 foreach ( var email in contact.Emails1 )
 {
     // first make sure the object is retrieved from the database
     var updateemail = Updatecontact.Emails1.FirstOrDefault( e => e.id == email.id );
     // then update its properties
     updateemail.email1 = email.email1;
 }

 // do the same for phones and tags

这篇关于实体框架插入新行而不是更新它们的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！