更新使用MVC 4和Entity Framework相关的数据？ [英] Updating related data using MVC 4 and Entity Framework?

问题描述

所以，我在保存其中包含相关的实体，当我保存它的新关系的空白创建数据的问题。

So, I have a problem in save data which contains related entities, when I save it a new relation blank is created.

例：

实体：

public class Project
{
    public int Id { get; set; }
    public int Code{ get; set; }
    public string Description{ get; set; }

    public virtual Client Client { get; set; }
}


public class Client
{
    public int Id { get; set; }
    public int Code { get; set; }
    public string Name { get; set; }
}

控制器GET：

public ActionResult Create()
{
    PopulateDropDownClienteList(String.Empty); //Returns to ViewBag to create a combobox .in view
    return View();
}

视图：

 @Html.DropDownListFor(m => m.Client.Id, new SelectList(ViewBag.Client_Id, "Id", "Name"), new { Name = "Client.Id" });

控制器POST：

The Controller POST:

[HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(string command, Project project)
    {
        try
        {
            if (ModelState.IsValid)
            {
                projectRepository = new ProjeRepository();
                Project pro = projectRepository.ReturnByCode(project.Code);

                if (pro == null)
                    projectRepository.Save(project);
                else
                    projectRepository.Update(project);

                PopulateDropDownClienteList(String.Empty);

                Return View();

            }
            else
            {
                return View(project);
            }
        }
        catch (Exception ex)
        {
            return View();
        }
    }

所以，当我保存数据，客户端不与项目关联。只是创造一个新的空白客户端。

So when I save the data, the client is not associated with the project. just creating a new blank Client.

推荐答案

您项目保存code未更新的实体，它的添加新所有的时间。

You Project Save code is not updating the entity, it is ADDING a new one all the time.

您应该有类似以下理由更新逻辑 -

You should have update logic similar to following grounds -

添加新条目FK，并将它与父记录关联 -

var entity = entities.Students.Where(p => p.Id == "2").First();
entity.StudentContact = new StudentContact() { Contact = "xyz", Id = "2" };

entities.Students.Attach(entity);
var entry = entities.Entry(entity);
// other changed properties
entities.SaveChanges();

要使用新的细节更新FK纪录 -

var entity = entities.Students.FirstOrDefault();
entity.StudentContact.Contact = "ABC";

entities.Students.Attach(entity);
var entry = entities.Entry(entity);
entry.Property(e => e.StudentContact.Contact).IsModified = true;
// other changed properties
entities.SaveChanges();

以上code，我有与StudentContacts FK关系的学生档案。我更新一个学生的联系信息，然后利用其附加更新到数据库中。

The above code, I have a Student records which has FK relationship with StudentContacts. I updated Contact information of a student and then updated it to database using ATTACH.

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