ASP.NET MVC 5在View中获取继承的类数据

Question

I'm learning asp.net MVC and I'm trying to build an application but i can't have data displayed in my view. I've search here but wasn't able to find an answer to this issue. I have a model structure with Person which is my base class and two other classes that inherited from Person - Professor and Student. What i want is when i click the Students tab in my application it displays only students data and when i click Professors it displays only professors data with their common data and specific for each type. Right now i have only one table "Person" with students and professors attributes. Thanks in advance!!

Here is my base class Person and subclasses Professor and Student

public abstract class Person
{
    public virtual int PersonID { get; set; }
    public virtual string FirstName { get; set; }
    public virtual string LastName { get; set; }
    public virtual string Email { get; set; }
    public virtual string Login { get; set; }
    public virtual string Senha { get; set; }
    public virtual string Address { get; set; } 
}
public class Professor : Person
{
    public string CREF { get; set; }
    public string Education { get; set; }
    public virtual ICollection<Session> Sessions { get; set; }
} 
public class Student : Person
{
    public DateTime SessionStart { get; set; }
    public DateTime SessionEnd { get; set; }
    public virtual ICollection<TSession> Sessions { get; set; }
}

and here is my StudentController

public class StudentController : Controller
{
    private SessionContext db = new SessionContext();

    public ActionResult Index()
    {
        return View(db.People.ToList());
    }
}

Here is my Index studentView

....

<table class="table">
    <tr>
        <th>@Html.DisplayNameFor(model => model.FirstName)</th>
        <th>@Html.DisplayNameFor(model => model.LastName)</th>
         ....
    </tr>
    @foreach (var item in Model) {
        <tr>
            <td>@Html.DisplayFor(modelItem => item.FirstName)</td>
            <td>@Html.DisplayFor(modelItem => item.LastName)</td>
            ....
        </tr>
    }
</table>

Answer 1

I have saved my original answer in a gist as it didn't really answer the OP's question. Ironically the source I was using was designed to solve the opposite problem, where two tables needed to be combined into a single page.

Here the OP is saying that there is a database table Persons from which we'd like to extrapolate two Views, Professor and Student , and display them on different pages.

Such that--

//StudentController.cs
public class StudentController : Controller
{
    private SessionContext db = new SessionContext();

    public ActionResult Index()
    {
        var result = db.People.Where(x => !string.IsNullOrEmpty(x.Education));
        return View(result.ToList());
    }
}

and...

//ProfessorController.cs
//...
    var result = db.People.Where(x => string.IsNullOrEmpty(x.Education));
//...

...could be one way of separating the views.

However, as suggested in comments, if your design requires these objects to be displayed and treated separately in the application, you may just want to have multiple tables. One example in TSQL:

CREATE TABLE dbo.Person (
    Id int NOT NULL PRIMARY KEY,
    Name nvarchar(200) NOT NULL --unicode
);
CREATE TABLE dbo.Professor (
    Id int NOT NULL PRIMARY KEY,
    Education nvarchar(50) NOT NULL,
    PersonId int FOREIGN KEY REFERENCES Person.Id
);
--etc

But since I'm not a DBA and you're using ASP.NET you can use Entity Framework's Code First table generation, which I think is what you're hinting at above:

public class Person
{
    public int PersonId { get; set; }
    [Required] // == NOT NULL
    public string Name { get; set; }
    // demais... (the rest)
}

public class Professor // no inheritance!
{
    public int ProfessorId { get; set; }
    [Required]
    public string Education { get; set; }
    [ForeignKey("PersonId")]
    public Person Person { get; set; }
}

Note that this is a 1-1 relationship, and honestly I haven't validated this. Julie Lerman has many posts on Microsoft's Data Developer Center website, such as this one that goes into these relationships. (That's my best Quick Googling (tm) and points to Entity Framework 4.1, so I'm sure you can find something newer. But the principles should still hold.)

Whew!

Answer 2

谢谢所有花时间尝试帮助我解决此问题的人，我能够从继承的类中提取特定属性，并以不同的视图显示它，因此，我决定创建两个表Student和Professor，这解决了我的问题。

Answer 3

This question has 2 parts, namely, displaying data on a view and getting the data from a database via some method like Entity Framework . And because this is an ASP.NET MVC question I am only going to answer the displaying of data on the view. How you get your data back is up to you.

I personally would have 2 tables in the database for this, one for students and one for professors. This is debatable but this is how I would do it.

You professor and student classes look correct to me.

You will need to create a view model for this. View models contain data that you pass to the view. I gave a detailed answer on what view models are. Please read it:

What is ViewModel in MVC?

First go and create your view model that you will send to the view. You will probably display other data on the screen, but I am only going to display a list of students and a list of professors. So for each you will have a property to contain the data:

public class ViewModel
{
     public List<Student> Students { get; set; }

     public List<Professor> Professors { get; set; }
}

In your Index action method you will create an instance of this view model, populate it with student and professor data and then send it through to the view:

public ActionResult Index()
{
     // Please make use of a repository to handle this
     // You need to set up your data layer to handle students and professors
     SessionContext db = new SessionContext();

     ViewModel model = new ViewModel();

     // Get all the students
     model.Students = db.Students.ToList();
     // Get all the professors
     model.Professors = db.Professors.ToList()

     return View(model);
}

Now you have your view model populated with student and professor data. You send it through to the view and the view will display it. You will need 2 HTML tables and have your tabs display the correct table when needed:

@model Project.Models.ViewModel

<table>
     @foreach (var student in Model.Students)
     {
          <tr>
               <td>@student.FirstName</td>
               <td>@student.FirstName</td>
          </tr>
     }
</table>

<table>
     @foreach (var professor in Model.Professors)
     {
          <tr>
               <td>@professor.FirstName</td>
               <td>@professor.FirstName</td>
          </tr>
     }
</table>

This is a simplistic approach and might not be what you are looking for but it will guide you on the correct path and give you ideas of what can be done.