视图模型和LINQ查询来表示Asp中的4个链接表.净MVC

Question

在将我的雇主内部系统从asp迁移到asp.net MVC之前，我使用一个典型的发票系统作为开发MVC和ViewModel知识的测试。

我知道ViewModels是在视图中显示信息的推荐方式-所以我希望有一些帮助"扁平化"视图模型:

表:Invoice, InvoiceItem, Payment, PaymentInvoice

Invoice和InvoiceItem是链接的，Payment(记录全部付款)和PaymentInvoice(列出付款涵盖的发票)也是链接的。

我想要一个ViewModel显示我:

InvoiceIdCustomerName发票总额(数量X单价加增值税)AmountAllocated(来自PaymentInvoice表)Outstanding (TotalofInvoice - AmountAllocated)

所以我认为我的ViewModel应该是:

public class InvoiceViewModel
{
    public Int InvoiceId { get; set; }
    public string CustomerName { get; set; }
    public decimal TotalofInvoice { get; set; }
    public decimal AmountAllocated { get; set; }
    public decimal Outstanding { get; set; }
}

我的领域模型是:

public class Invoice
{
    public int InvoiceId { get; set; }
    public int CustomerId { get; set; }
    public string CustomerName { get; set; }
    public string Email { get; set; }
    public DateTime InvDate { get; set; }
    public IList<InvoiceItem> InvoiceItems { get; set; }
}
public class InvoiceItem
{
    public int InvoiceItemId { get; set; }
    public int InvoiceId { get; set; }
    public string Item { get; set; }
    public string Description { get; set; }
    public int Quantity { get; set; }
    public decimal UnitPrice { get; set; }
    public decimal VAT { get; set; }
    public virtual Invoice Invoice { get; set; }
    // calculated fields
    public decimal Total
    {
        get { return Quantity * UnitPrice; }
    }
    public decimal VATAmount
    {
        get { return TotalPlusVAT - Total; }
    }
    public decimal TotalPlusVAT
    {
        get { return Total * (1 + VAT / 100); }
    }
}
public class Payment
{
    public int PaymentId { get; set; }
    public int CustomerId { get; set; }
    public DateTime DateReceived { get; set; }
    public decimal TotalReceived { get; set; }
    public IList<PaymentInvoice> PaymentInvoices { get; set; }
}
public class PaymentInvoice
{
    public int PaymentInvoiceId { get; set; }
    public int PaymentId { get; set; }
    public decimal AmountAllocated { get; set; }
    public int InvoiceId { get; set; }
    public virtual Payment Payment { get; set; }
}

我的问题是如何将Payment和PaymentInvoice表链接到Invoice和InvoiceItem表，所以我可以在控制器中使用LINQ查询来填充"扁平数据"的视图模型。

我也失去了LINQ查询-在LinqPad中我有:

from c in Invoices
join i in InvoiceItems on c.InvoiceId equals i.InvoiceId
join pi in PaymentInvoices on c.InvoiceId equals pi.InvoiceId
select new {...into ViewModel????...}

…但不知道之后该去哪里。

EDIT -我得到的最接近的是Sql来做到这一点:

SELECT     Invoices.InvoiceId, 
           Invoices.CustomerName, 
           (SUM(InvoiceItems.Quantity * InvoiceItems.UnitPrice)) AS TotalOfInvoice, 
           (SELECT     SUM(AmountAllocated) AS Expr1
                          FROM         PaymentInvoices
                          WHERE     (InvoiceId = Invoices.InvoiceId)) AS AmountAllocated, 
           SUM(InvoiceItems.Quantity * InvoiceItems.UnitPrice) 
           - (SELECT     SUM(AmountAllocated) AS Expr1
                          FROM         PaymentInvoices
                          WHERE     (InvoiceId = Invoices.InvoiceId)) AS Outstanding
FROM         Invoices LEFT OUTER JOIN
                  InvoiceItems ON Invoices.InvoiceId = InvoiceItems.InvoiceId
GROUP BY Invoices.InvoiceId, Invoices.CustomerName

谢谢你,马克

Answer 1

我认为你的Linq查询几乎是完美的，你只需要选择新的ViewModels:

from c in Invoices
join i in InvoiceItems on c.InvoiceId equals i.InvoiceId
join pi in PaymentInvoices on c.InvoiceId equals pi.InvoiceId
select new InvoiceViewModel {
    InvoiceId = c.InvoiceId,
    CustomerName = c.CustomerName,
    TotalofInvoice = c.InvoiceItems.Sum(invoiceitem => invoiceitem.Total(),
    AmountAllocated = ...
    Outstanding = ...
};