插入具有一对多关系但不在两个表中创建记录的新实体
本文关键字:两个 创建 记录 实体 新实体 一对多 关系 插入 | 更新日期: 2023-09-27 18:24:56
我正在使用MVC5和EF6 Code First创建一个新的Company
实体,该实体可以有许多Contact
实体。但是,只有Company
记录被写入数据库。
型号:
public class Company
{
public virtual int CompanyId { get; set; }
[Required]
public virtual string Name { get; set; }
[Required]
public virtual Address Address { get; set; }
[Required]
public virtual string Phone { get; set; }
public virtual string Email { get; set; }
// can have many Contacts
public virtual IEnumerable<Contact> Contacts { get; set; }
}
public class Contact
{
public virtual int ContactId { get; set; }
[Required]
public virtual string Title { get; set; }
[Required]
public virtual string Forename { get; set; }
[Required]
public virtual string Surname { get; set; }
[Required]
public virtual string Phone { get; set; }
public virtual string Email { get; set; }
// belongs to one Company
public virtual Company Company { get; set; }
}
控制器:
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Create_POST([Bind(Include = "CallerType,Name,Address,Phone,Email,Contacts")] CompanyViewModel viewModel)
{
if (ModelState.IsValid)
{
// tried commented code to make sure it wasn't a problem with my repository and contact records aren't saved to database...
//var context = new EfDbContext();
//var company = new Company
//{
// Name = viewModel.Name,
// Phone = viewModel.Phone,
// Address = viewModel.Address,
// Email = viewModel.Email
//};
//context.Companies.Add(company);
//var contact = new Contact
//{
// Company = company,
// Title = "mr",
// Forename= "f",
// Surname = "s",
// Phone = "132"
//};
//var contact2 = new Contact
//{
// Company = company,
// Title = "mr",
// Forename = "for",
// Surname = "sur",
// Phone = "987"
//};
//var contacts = new List<Contact> {contact, contact2};
//company.Contacts = contacts;
//context.SaveChanges();
var contacts = viewModel.Contacts.Select(c => new Contact
{
Title = c.Title,
Forename = c.Forename,
Surname = c.Surname,
Phone = c.Phone,
Email = c.Email
});
var company = new Company
{
Name = viewModel.Name,
Phone = viewModel.Phone,
Address = viewModel.Address,
Email = viewModel.Email,
Contacts = contacts
};
await _companyRepository.CreateAsync(company);
var redirectUrl = new UrlHelper(Request.RequestContext).Action("Create", "Enquiry", new { id = company.CompanyId, callerType = viewModel.CallerType });
return Json(new { Url = redirectUrl });
}
Response.StatusCode = 400;
return PartialView("~/Views/Company/_Create.cshtml", viewModel);
}
存储库:
public async Task<TEntity> CreateAsync(TEntity entity)
{
if (entity == null) throw new ArgumentNullException(nameof(entity));
DbContext.Set<TEntity>().Add(entity);
await DbContext.SaveChangesAsync();
return entity;
}
我的印象是,DbContext
会"知道",因为它的Contacts
集合已填充,它会创建链接到创建的Company
的Contact
记录。还是我必须创建一个Contact
,因为这是一个包含外键的表,EF会"知道"首先创建Company
?
还是需要先使用SaveChanges()
保存Company
实体,然后将其分配给Contact
记录并执行第二个SaveChanges()
如果是这种情况,那么我需要使用Database.BeginTransaction()
吗?
任何关于这方面的指导都将是伟大的,因为这是我第一次使用实体框架。
Contacts
必须是ICollection
。EF不支持IEnumerable
作为导航属性,因为无法向其中添加项目。
这也意味着您应该更改创建contacts
:的代码
var contacts = viewModel.Contacts.Select(c => new Contact
{
Title = c.Title,
Forename = c.Forename,
Surname = c.Surname,
Phone = c.Phone,
Email = c.Email
}).ToList(); // <= ToList() added
您的关系应该在DbContext中通过重写OnModelCreating方法来设置
我自己是实体框架的新手,但发现方法名称有助于学习如何建立关系
希望以下内容能帮助
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Company>()
.HasMany(c => c.Contacts)
.WithRequired(co => co.Company)
.HasForeignKey(co => co.CompanyId);
}
您还可以在关系中设置级联,这样当一个实体被删除时,相关的实体也会被删除,如果您需要删除公司,这可能是需要考虑的问题