我不知道如何构建多对多关系，并为用户提供输入数据的正确表单。我有一个Class对象，我有一个教师对象，教师可以有很多班级，班级可以有很多老师，我不能使用复选框，因为我们拥有的教师人数超过100人以及班级。我的模型如下
public abstract class Person
{
public int PersonId { get; set; }
[Required]
[StringLength(50, ErrorMessage = "First name can not be longer than 50 characters.")]
[Display(Name = "First Name")]
public string FirstName { get; set; }
[Required]
[StringLength(50, ErrorMessage = "Last name can not be longer than 50 characters.")]
[Display(Name = "Last Name")]
public string LastName { get; set; }
[Display(Name = "Middle Initial")]
public string MidInit { get; set; }
[Display(Name = "Contact Number")]
public string PhoneNo { get; set; }
[EmailAddress]
[Display(Name = "Work Email")]
public string Email { get; set; }
[DataType(DataType.MultilineText)]
[Display(Name = "Notes")]
public string Notes { get; set; }
public int? ConsId { get; set; }
public string FullName
{
get
{
string firstName = string.IsNullOrWhiteSpace(this.FirstName) ? "" : this.FirstName;
string midInit = string.IsNullOrWhiteSpace(this.MidInit) ? "" : this.MidInit;
string lastName = string.IsNullOrWhiteSpace(this.LastName) ? "" : this.LastName;
return string.Format("{0} {1} {2} {3} {4}", firstName, " ", midInit, " ", LastName);
}
}
}
public class Teacher : Person
{
public Teacher()
{
Classes = new HashSet<AClass>();
}
[Display(Name = "Classes Taught")]
public virtual ICollection<AClass> Classes { get; set; }
public override string ToString()
{
return this.PersonId.ToString();
}
}
public class AClass
{
public AClass()
{
Instructors = new HashSet<Teacher>();
ClassEndDate = DateTime.Today;
}
public int AClassId { get; set; }
[Display(Name = "Class Number")]
public string ClassNo { get; set; }
[Display(Name = "Class Name")]
public string ClassName { get; set; }
[Display(Name = "Section Number")]
public string SectionNumber { get; set; }
[DataType(DataType.Date)]
[Display(Name = "Class Start Date")]
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:MM/dd/yyyy}")]
[Required]
public DateTime ClassStartDate { get; set; }
[DataType(DataType.Time)]
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:hh:mm tt}")]
[Display(Name = "Class Start Time")]
public DateTime? ClassStartTime { get; set; }
[Display(Name = "Class End Date")]
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:MM/dd/yyyy}")]
[Required]
public DateTime ClassEndDate { get; set; }
public virtual ICollection<Teacher> Instructors { get; set; }
public IEnumerable<int> ClassInstructorId { get; set; }
public ICollection<Teacher> AllInstructors { get; set; }
public string ClassDisplay
{
get
{
return ClassNo + " - " + ClassName + " Start Date: " + ClassStartDate.ToShortDateString();
}
}
}
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
public ApplicationDbContext()
: base("DefaultConnection", throwIfV1Schema: false)
{
}
public DbSet<AClass> Classes { get; set; }
public DbSet<Person> Persons { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
modelBuilder.Entity<AClass>().HasMany<Teacher>(i => i.Instructors).WithMany(c => c.Classes).Map(m =>
{
m.MapLeftKey("AClassId");
m.MapRightKey("PersonId");
m.ToTable("ClassInstructor");
});
modelBuilder.Entity<IdentityUserLogin>().ToTable("AspNetUsers").HasKey<string>(l => l.UserId);
modelBuilder.Entity<IdentityRole>().ToTable("AspNetRoles").HasKey<string>(r => r.Id);
modelBuilder.Entity<IdentityUserRole>().ToTable("AspNetUserRoles").HasKey(r => new { r.RoleId, r.UserId });
base.OnModelCreating(modelBuilder);
}
public static ApplicationDbContext Create()
{
return new ApplicationDbContext();
}
}
我的crud创建表单我将其修改为包含多选列表如下
@using (Html.BeginForm())
{ @ Html.AntiForgeryToken（）
<div class="form-horizontal">
<h4>AClass</h4>
<hr />
@Html.ValidationSummary(true, "", new { @class = "text-danger" })
<div class="form-group">
@Html.LabelFor(model => model.ClassNo, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.ClassNo, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.ClassNo, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.ClassName, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.ClassName, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.ClassName, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.SectionNumber, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.SectionNumber, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.SectionNumber, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.Label("Teacher", htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-5">
@Html.ListBoxFor(model => model.ClassInstructorId, new MultiSelectList(Model.AllInstructors, "PersonID", "FullName"), new { Multiple = "multiple" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.ClassStartDate, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.ClassStartDate, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.ClassStartDate, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.ClassStartTime, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.ClassStartTime, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.ClassStartTime, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.ClassEndDate, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.ClassEndDate, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.ClassEndDate, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</div>
</div>
}
<div>
@Html.ActionLink("Back to List", "Index")
</div>
我的类控制器如下创建操作
// GET: Classes/Create
public ActionResult Create()
{
AClass model = new AClass();
model.AllInstructors = db.Persons.OfType<Teacher>().ToList();
model.ClassInstructorId = Enumerable.Empty<int>();
foreach (Teacher inst in model.Instructors)
{
model.ClassInstructorId = model.ClassInstructorId.Concat(new[] { inst.PersonId });
}
model.ClassStartDate = DateTime.Today;
return View(model);
}
// POST: Classes/Create
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
// public ActionResult Create([Bind(Include = "AClassId,ClassNo,ClassName,SectionNumber,ClassStartDate,ClassStartTime,ClassEndDate")] AClass aClass)
public ActionResult Create(AClass aClass, )
{
if (ModelState.IsValid)
{
db.Classes.Add(aClass);
db.SaveChanges();
return RedirectToAction("Index");
}
return View(aClass);
}
表已成功创建，但我的问题是如何在创建类时将教师分配给类，以及如何在编辑的情况下将它们带回来。任何见解将不胜感激。我虽然EF处理相关数据。
答案 0 :(得分：0)
这就是我所做的，它像魅力一样工作感谢您的帮助，我希望这段代码可以帮助我所在地的其他人。
我将classId从int
更改为Guid然后在我的控制器Post方法
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(AClass aClass, )
{
if (ModelState.IsValid)
{
aClass.AClassId = Guid.NewGuid();
aClass.Instructors = db.Persons.OfType<Teacher>().Where(m => aClass.ClassInstructorId.Contains(m.PersonId)).ToList();
db.Classes.Add(aClass);
db.SaveChanges();
return RedirectToAction("Index");
}
return View(aClass);
}
和entityframework负责其余部分。