的LINQ如何查詢項目的列表基於父項目

喜的特性的子集的一個組合列表說我有對象：的LINQ如何查詢項目的列表基於父項目

public class InvoiceLine 
{ 
}

和

public class InvoiceHeader 
{ 
    public char Group { get; set; } 
    public List<InvoiceLine> InvoiceLines { get; set; } 
}

數據爲他們設置如下：

var invoiceLine1 = new InvoiceLine(); 
var invoiceLine2 = new InvoiceLine(); 
var invoiceLine3 = new InvoiceLine(); 
var invoiceLine4 = new InvoiceLine(); 
var invoiceLine5 = new InvoiceLine(); 
var invoiceLine6 = new InvoiceLine(); 
var invoiceLine7 = new InvoiceLine(); 
var invoiceLine8 = new InvoiceLine(); 

var invoiceHeader1 = new InvoiceHeader { Group = 'A', InvoiceLines = new List<InvoiceLine> { invoiceLine1, invoiceLine2 } }; 
var invoiceHeader2 = new InvoiceHeader { Group = 'A', InvoiceLines = new List<InvoiceLine> { invoiceLine3, invoiceLine4 } }; 
var invoiceHeader3 = new InvoiceHeader { Group = 'B', InvoiceLines = new List<InvoiceLine> { invoiceLine5, invoiceLine6 } }; 
var invoiceHeader4 = new InvoiceHeader { Group = 'B', InvoiceLines = new List<InvoiceLine> { invoiceLine7, invoiceLine8 } }; 

var invoiceHeaders = new List<InvoiceHeader> 
{ 
    invoiceHeader1, 
    invoiceHeader2, 
    invoiceHeader3, 
    invoiceHeader4 
};

我想要得到的是每個組的invoiceLines列表。

所以我想爲A組：

invoice1，invoice2，invoice3和invoice4

和B組：

invoice5，invoice6，invoice7和invoice8

最遠的我得到是：

var invoiceLinesGroupA = invoiceHeaders.SelectMany(x => x.InvoiceLines);

據我所知，將得到所有八個invoiceLines。不知何故，我需要按羣組進行區分，以獲得組A的組羣，併爲組B做同樣的事情。

任何人都可以幫忙嗎？

來源

2013-06-25 user2005657

你可能只是想組由該組的發票標題：

var groups = invoiceHeader.GroupBy(ih => ih.Group);

然後你就可以訪問該組的線路：

foreach(var group in groups) 
{ 
    Console.WriteLine("Group " + group.Group); 
    Console.WriteLine("Lines:"); 
    Console.WriteLine(string.Join(", ", group.SelectMany(h => h.InvoiceHeader.InvoiceLines))); 
}

輸出會是這樣的

Group A 
Lines: 
invoice1, invoice2, invoice3, invoice4 

Group B 
Lines: 
invoice5, invoice6, invoice7, invoice8

來源

2013-06-25 08:41:55 Matten

var regrouped = invoiceHeaders 
    .SelectMany(
     header => header.InvoiceLines, 
     (header, line) => new { header, line } 
    ) 
    .GroupBy(
     o => o.header.Group, 
     o => o.line, 
     (groupName, lines) => new InvoiceHeader 
     { 
      Group = groupName, 
      InvoiceLines = lines.ToList() 
     } 
    ) 
    .ToList();

來源

2013-06-25 08:42:44

看看這個過載的Enumerable.SelectMany

var result = invoiceHeaders 
       .SelectMany(x => x.InvoiceLines, 
          (group, InvoiceLine)=>{group, InvoiceLine}) 
       .Where(res => res.group='A');

來源

2013-06-25 08:43:07

試過這個不會編譯 – user2005657

這應做到：

 var test = from h in invoiceHeaders 
        from i in h.InvoiceLines 
        group i by h.Group 
        into g 
        select new {key = g.Key, rows = g.ToArray()};

然後，您可以像這樣訪問test.Where(x => x.key == 'A').rows

來源

2013-06-25 08:43:47 Simon

var q = from current in myInvoiceHeaders 
       join c in myInvoiceLines on current.Id equals c.Header.Id into linesByHeader      
       select new { 
        Header = current, 
        Lines = linesByHeader 
       };

的項目，你有一個標準的前提下，應該工作加入兩個實體。

來源

2013-06-25 08:43:59

的LINQ如何查詢項目的列表基於父項目

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