Automapper实体框架外键为null [英] Automapper entity framework foreign key is null

问题描述

我正在尝试使用实体框架更新数据库，我使用自动映射器将我的实体映射到视图模型，并以相同的方式将其映射回去:

I am trying to update the database using entity framework, I map my entities to viewmodels using automapper, and map it back the same way:

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit([FromJson] MyCVViewModel model)
{
    var userId = User.Identity.GetUserId();
    //find the cv
    CV cv = repository.FindCV(model.CVId);

    //auto mapper mapping
    Mapper.CreateMap<MyCVViewModel, CV>();
    Mapper.CreateMap<MyCompanyViewModel, Company>();
    cv = Mapper.Map<MyCVViewModel, CV>(model, cv);

    //edit
    repository.EditCV(cv);
}

当我将其映射回时，公司实体内部的外键CVid变为0，我认为在映射过程中丢失了一些东西，如何映射外键?

When I map it back, the foreign key CVid inside company entity becomes 0, i think something was lost during the mapping process, how do you map the foreign key?

这是我的视图模型和实体:

Here is my view model and entity:

查看模型:

public class MyCVViewModel
{
    public int CVId { get; set; }

    [Required]
    [StringLength(100, ErrorMessage = "Title cannot exceed 100 characters.")]
    [Display(Name = "Title")]
    public string Title { get; set; }
    [Required]
    [StringLength(1000, ErrorMessage = "Statment cannot exceed 1000 characters.")]
    [Display(Name = "Statement")]
    public string Statement { get; set; }

    public bool Reference { get; set; }

    public List<MyCompanyViewModel> Companies { get; set; }
}

public class MyCompanyViewModel
{
    [Required]
    [StringLength(100, ErrorMessage = "Company Name cannot exceed 100 characters.")]
    [Display(Name = "Company Name")]
    public string CompanyName { get; set; }
    [Required]
    [StringLength(100, ErrorMessage = "Job Title cannot exceed 100 characters.")]
    [Display(Name = "Job Title")]
    public string JobTitle { get; set; }
    [Required]
    [DataType(DataType.Date)]
    [Display(Name = "Start Date")]
    public DateTime StartDate { get; set; }
    [Required]
    [DataType(DataType.Date)]
    [Display(Name = "End Date")]
    public DateTime EndDate { get; set; }
    [Required]
    [StringLength(1000, ErrorMessage = "Job Description cannot exceed 1000 characters.")]
    [Display(Name = "Job Description")]
    public string Description { get; set; }
}

实体:

public class CV
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int CVId { get; set; }
    public string Title { get; set; }
    public string Statement { get; set; }
    public bool Reference { get; set; }

    public virtual ICollection<Company> Companies { get; set; }
}

public class Company
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int CompanyId { get; set; }

    public string CompanyName { get; set; }
    public string JobTitle { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }
    public string Description { get; set; }

    public virtual CV CV { get; set; }
    public int CVId { get; set; }
}

这是我尝试更新时的错误消息:

and this is the error message when I try to update:

操作失败:由于一个或多个外键属性不可为空，因此无法更改该关系.对关系进行更改时，相关的外键属性将设置为空值.

我知道问题出在哪里，但不知道如何告诉自动映射器保留外键值

I see where the problem is, but don't know how to tell automapper to retain foreign key value

推荐答案

MyCompanyViewModel类不包含CVId属性的定义，因此默认情况下，Automapper不知道他应该带哪个位置用于注入Company的CVId属性的值.只需定义它即可:

MyCompanyViewModel class does not contain a definition of CVId property, so by default Automapper does not know where he should take a value for injecting into Company's CVId property. Just define it:

public class MyCompanyViewModel
{
    public int CVId { get; set; }
    // Other properties
}

然后为每个CompanyViewModel在视图中添加相应的隐藏输入字段:

Then for each CompanyViewModel add corresponding hidden input field into the view:

@for (int i = 0; i < Model.Companies.Count; i++)
{

    // ...

    @Html.HiddenFor(m => Model.Companies[i].CVId)

    // ...

}

你很好！

这篇关于Automapper实体框架外键为null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IT屋！