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POLINQ sort a flat list based on childorder
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  1. POLINQ sort a flat list based on childorder
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    copied!<p>I am currently trying to figure out a good way to sort my elements with LINQ and C#, but I am kinda failing to do so.</p> <p>For the problem let assume you have the following Table</p> <pre><code>---TempTable ID (int) ParentID (int) Name (varchar) SortOrder (int) </code></pre> <p>The ID and ParentID are related to each other and give me a self hierachical data structure. The root elements have a null in the ID Field. The SortOrder is only a portion of the whole table and based on the ParentID, so the elements that share the same ParentID do have 1, 2, 3 in it.</p> <p>Lets further assume the following data:</p> <pre><code>ID = 1 ParentID = null Name = Test 1 SortOrder = 1 ID = 2 ParentID = 1 Name = Test 2 SortOrder = 1 ID = 3 ParentID = 1 Name = Test 3 SortOrder = 2 ID = 4 ParentID = 2 Name = Test 4 SortOrder = 1 </code></pre> <p>My desired flat list should have the following order:</p> <pre><code>Test 1 //root element with sort order 1 = very top Test 2 //child element of root with sort order 1 Test 4 //child element of test 2 with sort order 1 Test 3 //child element of root with sort order 2 </code></pre> <p>Also I like to get the object itself without only getting a portion of information threw the usage of select new ...</p> <p>This is one of my failed tries:</p> <pre><code>from x in EntityModel.TempTables //DbSet&lt;TempTable&gt; by EntityFramework - which already holds all elements orderby x.SortOrder from y in x.TempTableChildren //Navigation Property by EntityFramework orderby y.SortOrder select y </code></pre> <p>Thanks in advance for your help.</p> <p><strong>Edit:</strong></p> <p>The order with the ParentID maybe helpfull, with the given TestData since the ID, ParentIDs are in perfect order but this isnt the case in a real live application since its data driven, someone could delete a entry create a new one and place it in a certain order under a parent and you would have something like :</p> <pre><code>ID = 193475037 ParentID = 2 Name = Test 192375937 SortOrder = 25 </code></pre> <p>Now in the application it would be possible to move this one and the ParentID and SortOrder would change randomly to something like:</p> <pre><code>ID = 193475037 ParentID = 456798424 Name = Test 192375937 SortOrder = 4 </code></pre> <p>To furhter explain the problem here is some code - how I would do it without 1 beautifull Linq Query but with 2 and some yield return:</p> <pre><code>public class LinqTestDemo { Random rand = new Random(); List&lt;TempTable&gt; list = new List&lt;TempTable&gt;(); public List&lt;TempTable&gt; GetFlatData() { list = GetTestData(); var rootElement = (from x in list where x.ParentID == null orderby x.SortOrder select x).ToList(); var flatList = OrderChilds(rootElement).ToList(); foreach (var tempTable in flatList) { Console.WriteLine(string.Format("ID = {0} - ParentID = {1} - Name = {2} - SortOrder = {3}", tempTable.ID, tempTable.ParentID, tempTable.Name, tempTable.SortOrder)); } return flatList; } private IEnumerable&lt;TempTable&gt; OrderChilds(List&lt;TempTable&gt; enumerable) { foreach (var tempTable in enumerable) { yield return tempTable; TempTable table = tempTable; var childs = OrderChilds((from x in list where x.ParentID == table.ID orderby x.SortOrder select x).ToList()); foreach (var child in childs) { yield return child; } } } public List&lt;TempTable&gt; GetTestData() { var returnValue = new List&lt;TempTable&gt;(); for (int i = 0; i &lt; 50; i++) { var tempTable = new TempTable(); tempTable.ID = i; if (i == 0) tempTable.ParentID = null; else tempTable.ParentID = rand.Next(0, i); var maxSortOrder = (from x in returnValue where x.ParentID == tempTable.ParentID select (int?)x.SortOrder).Max(); if (maxSortOrder.HasValue) tempTable.SortOrder = maxSortOrder.Value + 1; else tempTable.SortOrder = 1; tempTable.Name = string.Format("Test {0:00}", i); returnValue.Add(tempTable); } return returnValue; } public class TempTable { public int ID { get; set; } public int? ParentID { get; set; } public string Name { get; set; } public int SortOrder { get; set; } } } </code></pre> <p>@ Breadth-First vs Depth-First Traversal: After some reading I would say my desired result would be Depth-First Traversal, where the elements at the same level depth should be ordered by the property SortOrder.</p>
 

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