How to find recursive Parent Child hierarchy Dynamically using Linq in Mvc

Question

can i do it in linq to find parent-child relationship dynamically ?

when user gives the child input,we have to find out the immediate parent and Top Level parent for the child.

Schema:

**LocationId**   **LocationName**  **ParentId**
 1               InterNational          0
 2                National              1
 3                Regional              2
 4                SubRegional           3
 5                Area                  4
 6                City                  5
 7                Town                  6
 8              Municipality            7



Input:When user type input as Area
Outpt:immediate parent: SubRegional
Top parent:International
total parent:4

if:town
immediate parent:City
top parent:international
total parent:6

class

     public class ParentChild
        {
            public int LocationId { get; set; }
            public string LocationName { get; set; }
            public int parentId { get; set; }

            public static List<ParentChild> LocationParent()
            {
                var s = new List<ParentChild>{
                new ParentChild {LocationId=1,LocationName="InterNational",parentId=0},
                new ParentChild {LocationId=2,LocationName=" National",parentId=1},
                new ParentChild {LocationId=3,LocationName=" Regional ",parentId=2},
                new ParentChild {LocationId=4,LocationName=" SubRegional",parentId=3},
                new ParentChild {LocationId=5,LocationName="Area ",parentId=4},
                new ParentChild {LocationId=6,LocationName=" City ",parentId=5},
                new ParentChild {LocationId=7,LocationName="Town ",parentId=6},
                new ParentChild {LocationId=8,LocationName="Municipality ",parentId=7}
                };

                return s;

            }

        }


        public class ParentChildViewModel()
        {
            public int LocationId { get; set; }
            public string LocationName { get; set; }
            public int parentId { get; set; }
            public string ParentName{get;set;}
            public int immediateparentId {get;set;}
            public string immediateparentName {get;set;}


        }

controller

   public ActionResult ParentChilds(string x)
        {

            var ss = from y in ParentChild.LocationParent()
                     where y.LocationName == x
                     select 
-- How to do this in linq logic here?how i have write the logic

            return View(ss);


        }

View:

@model IEnumerable <Dataclasses.ParentChildViewModel>


@{
    ViewBag.Title = "ParentChilds";
}

<h2>ParentChilds</h2>

@foreach (var x in Model)
{
   <p>currentLocationName: @x.LocationName</p>
    <p>currentLocationId :@x.LocationId</p>

    <p>LocationTopParentId :@x.parentId</p>
   <p>LocationTopParent:@x.ParentName</p>

<p>LocationimmediateparentId :@x.immediateparentId</p>
   <p>LocationimmediateparentName:@x.immediateparentName</p>
    <br />

}

you don't give any information on the internal data structures used -- you just show the data model. please give these details if you expect a usable result. — Hogan
– Hogan, Commented Nov 13, 2015 at 19:53
I would recommend changing your parentId of International to null instead of 0. Then set up a self-referencing foreign key constraint on the table (ParentId must point to a valid id in the same table), and then update your data context. You should then have a property called Parent on your ParentChild class, in which you can use to reference the direct parent. — Robert McKee
– Robert McKee, Commented Nov 13, 2015 at 21:26

Sam.C · Accepted Answer · 2015-11-13 21:30:53Z

2

Something reusable might look like this

public static class MyExtensions
    {
        public static List<T> Parents<T>(this List<T> list, T current, Func<T, int> getId, Func<T, int> getPid)
        {
            List<T> returnlist = new List<T>();

            T temp = list.FirstOrDefault(x => getPid(current) == getId(x));
            while (temp != null)
            {
                returnlist.Add(temp);
                current = temp;
                temp = list.FirstOrDefault(x => getPid(current) == getId(x));
            }

            return returnlist;
        }
    }

and for your specific case it would them be used as

var locations = ParentChild.LocationParent();
            var parents = locations.Parents(locations[6], x => x.LocationId, x => x.parentId);
            Console.WriteLine( "Immediate Parent {0}, top - parent:{1}, count : {2}",
            parents.First().LocationName,
            parents.Last().LocationName,
            parents.Count );

answered Nov 13, 2015 at 21:30

Sam.C

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1 Comment

Hogan Over a year ago

This is cute -- very linqy to create a list of the path to the top. It could also be implemented without an extension using Aggregate

Hogan · Accepted Answer · 2015-11-13 20:28:47Z

0

I'd use linq to put the data in a dictionary, then it is a simple search and lookup.

void Main()
{

  List<loc> basedata = new List<loc>() 
  {
     new loc() { ID = 1, name = "InterNational", pID = 0 },
     new loc() { ID = 2, name = "National", pID = 1 },
     new loc() { ID = 3, name = "Regional", pID = 2 },
     new loc() { ID = 4, name = "SubRegional", pID = 3 },
     new loc() { ID = 5, name = "Area", pID = 4 },
     new loc() { ID = 6, name = "City", pID = 5 },
     new loc() { ID = 7, name = "Town", pID = 6 },
     new loc() { ID = 8, name = "Municipality", pID = 7 },
  };

  Dictionary<int,loc> data = basedata.ToDictionary(x => x.ID);

  string test1 = "Area";

  loc test1parent = data[data.First(x => x.Value.name == test1).Value.pID];
  loc top1;
  for(top1 = data.First(x => x.Value.name == test1).Value;top1.pID!=0;top1 = data[top1.pID]);

  Console.WriteLine("Immediate Parent = "+test1parent.name);
  Console.WriteLine("Top parent = "+top1.name);

  string test2 = "Town";

  loc test2parent = data[data.First(x => x.Value.name == test2).Value.pID];
  loc top2;
  for(top2 = data.First(x => x.Value.name == test2).Value;top2.pID!=0;top2 = data[top2.pID]);

  Console.WriteLine("Immediate Parent = "+test2parent.name);
  Console.WriteLine("Top parent = "+top2.name);

}


public class loc
{
   public int ID { get; set; }
   public string name { get; set; }
   public int pID { get; set; }
}

answered Nov 13, 2015 at 20:28

Hogan

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2 Comments

Robert McKee Over a year ago

I've deleted my answer, but this is essentially the same answer I had 10 minutes earlier but building your own lookups instead of letting LINQ do it automatically. I realized that the OP couldn't have used LINQs automatic generation of virtual properties because his table is setup odd. He uses 0 to denote no parent instead of null, which means he can't possibly have referential integrity set up correctly on the table (no record exists with an id of 0), and I don't believe LINQ would allow you to set up a navigation property either for the same reason(s).

Hogan Over a year ago

@RobertMcKee - yes I agree - there are other strange things about his example code, having a list inside of the ParentChild class makes no sense to me (given the other properties). I wrote my answer to be self contained which might prove helpful.

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