显示/列出来自其他模型（ViewModel）的数据？

Question

I have a customer model

public class Customer
    {
        public int CustomerID { get; set; }
        public string CustomerName { get; set; }
        public string CustomerAddress1 { get; set; }
        public string CustomerAddress2 { get; set; }
        public string CustomerAddress3 { get; set; }
        public string CustomerAddress4 { get; set; }
        public string CustomerAddress5 { get; set; }
        public string CustomerAddress6 { get; set; }
        public string CustomerAddress7 { get; set; }
}

I want to display all info from all customers in a profile view. I guess it is best to use a viewmodel because I also want to show other information in profile.

I created a viewmodel

 public class CustomerViewModel
    {
        public string CustomerAddress1 { get; set; }
        public string CustomerAddress2 { get; set; }
        public string CustomerAddress3 { get; set; }
    }

I do not really know how my profile controller should look like and have tested

        CustomerViewModel ViewModel = new CustomerViewModel();

        return View(ViewModel);

Viewmodel is null.

Normally, if I want to get all customers but in the customer Controller I do like this.

var customer = db.Customers.ToList();
return customer

And how should I list all the customers in the profile view?

This is not working

@model xxx.ViewModels.CustomerViewModel

@foreach (var item in Model)
{
    item.Customer.CustomerAddress2
}

Answer 1

You want to list multiple viewmodels, so create a collection:

var allCustomers = db.Customers.ToList();

Then map that to your viewmodel:

var allCustomersProfiles = allCustomers.Select(c => new CustomerViewModel
{
    CustomerAddress1 = c.CustomerAddress1,
    CustomerAddress2 = c.CustomerAddress2,
    CustomerAddress3 = c.CustomerAddress3,  
}).ToList();

You can simplify this by directly projecting onto your viewmodel, causing the optimal SQL to be generated and only one object per row to be instantiated instead of two:

var allCustomersProfiles = db.Customers.Select(c => new CustomerViewModel
{
    // ...
}.ToList()

Then tell your view to expect an enumerable model (you're going to pass List<T> but IEnumerable<T> works just as well):

@model IEnumerable<xxx.ViewModels.CustomerViewModel>

@foreach (var item in Model)
{
    item.Customer.CustomerAddress2
}

And return the collection to your view:

return View(allCustomersProfiles);

Answer 2

I can think of 2 ways of doing this, namely:

• Return a list of customer view models containing only customer-related data
• Return a customer view model with a list of customers and any non-related customer data

Regarding my first option, you can return a list of customer view models to the view. This will only contain customer-related data, nothing else:

public class CustomerViewModel
{
     public int Id { get; set; }

     public string Name { get; set; }

     public string AddressLine1 { get; set; }

     public string AddressLine2 { get; set; }

     public string AddressLine3 { get; set; }

     // Add more customer-related properties if needed
}

In your controller's action method you will retrieve your list of customers, loop through each customer and populate a view model item for each customer and add it the customer view model list:

public class CustomerController : Controller
{
     private ICustomerRepository customerRepository;

     public CustomerController(ICustomerRepository customerRepository)
     {
          this.customerRepository = customerRepository;
     }

     public ActionResult Profile()
     {
          List<CustomerViewModel> customerViewModels = new List<CustomerViewModel>();
          List<Customer> customers = customerRepository.GetAll();
          foreach (Customer customer in customers)
          {
               CustomerViewModel customerViewModel = new CustomerViewModel();
               customerViewModel.Id = customer.Id;
               customerViewModel.Name = customer.Name;
               // Populate the rest of the properties

               customerViewModels.Add(customerViewModel);
          }

          return View(customerViewModels);
     }
}

Once the list of customer view models is populated then you send this list to the view. The view will receive a strongly-typed list of customer view models:

@model List<YourProject.ViewModels.CustomerViewModel>

@foreach (var customerViewModel in Model)
{
     <p>@customerViewModel.Id - @customerViewModel.Name</p>
}

The second option is to return a customer view model to the view containing a list of customers and any other data that that you want to use in your view. Let's say that you want to display store information as well as a list of customers for that store:

public class CustomerViewModel
{
     public CustomerViewModel()
     {
          Customers = new List<Customer>();
     }

     public List<Customer> Customers { get; set; }

     public string StoreName { get; set; }
}

In your controller action method you would populate the list of customers and store information:

public ActionResult Profile()
{
     CustomerViewModel customerViewModel = new CustomerViewModel();
     customerViewModel.Customers = customerRepository.GetAll();
     customerViewModel.StoreName = "Test Store Name";

     return View(customerViewModel);
}

When the customer list and store information is populated then send this customer view model to the view:

@model YourProject.ViewModels.CustomerViewModel

<div>@Model.StoreName</div>
@foreach (var customer in Model.Cutomers)
{
     <p>@customer.Id - @customer.Name</p>
}

I hope this helps.