Asp.net mvc 在Asp.NETMVC中表示4个链接表的Viewmodel和LINQ查询

我正在使用一个典型的发票系统作为开发MVC和ViewModel知识的测试，然后将我的雇主内部系统从asp迁移到asp.net MVC

我知道ViewModels是在视图中显示信息的推荐方式-因此我希望获得一些帮助“展平”viewmodel以实现以下目的：

表：发票、发票项、付款、付款发票

发票和发票项被链接，付款（记录总体付款）和付款发票（列出付款涵盖的发票）也被链接

我想要一个ViewModel向我展示：

发票ID 客户名称 发票总额（数量X单价加增值税） 未分配金额（来自PaymentInvoice表） 未分配（总票数-未分配票数）

因此，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; }
}

…但不确定之后该去哪里

编辑-我得到的最接近的Sql是：

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,

---

Mark

我认为您的Linq查询几乎完美您只需要选择新的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 = ...
};

---

您好@Kenneth-谢谢-我猜我的思路是对的，但我没有取得任何进展-我已经发布了工作SQL语句-我想知道是否有人可以帮助扩展我的Linq/Kenneths Linq，以展示该语句应该如何在Linq中转换为工作语句？谢谢，标记SQL和LINQ查询之间的区别是“内部联接”与“左外部联接”。在“LINQ left outer join”上进行一些谷歌搜索，以获得一些示例，例如感谢-使用它，我可以让它显示单个项目，但我希望在查询中对项目进行求和-我现在拥有的是：var invs=发票中的发票连接发票中的项目发票上的项目。InvoiceId等于项目。InvoiceId等于gj.DefaultIfEmpty（）从gj.DefaultIfEmpty（）中的子项目将gj转换为新的{invoice.CustomerName，costs=（子项目==null？0:子项目.UnitPrice）}；（刚刚尝试了一个链接，看看是否可以正常工作）

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 = ...
};