Get unique objects From List of Objects

Question

I have class object like this:

    public class SD
    {
        public string s { get; set; }
    }

    public class Obj
    {
        public string p { get; set; }
        public string u { get; set; }
        public List<SD> sD { get; set; }
    }

    public class ObjAssignStudy
    {
        public List<Obj> obj { get; set; }
    }

And I get that data in this way:

{
  "obj":[
    {"p":"1","usertype":"A","studyData":[{"study":"1"},{"study":"2"}]},
    {"p":"2","usertype":"A","studyData":[{"study":"1"}]}
    {"p":"1","usertype":"A","studyData":[{"study":"2"},{"study":"3"}]}
  ]
}

What i want is, I want to get distinct P and append coresponding s to it ie. I want final object to contain data like this:

{
  "obj":[
    {"p":"1","usertype":"A","studyData":[{"study":"1"},{"study":"2"},{"study":"3"}]},
    {"p":"2","usertype":"A","studyData":[{"study":"1"}]}
  ]
}

Any way by which I can achieve this in c# or linq?

Answer 1

var objs = new List<Obj>(){
    new Obj 
    { 
        p = "1",
        u = "A",
        sD = new List<SD>() {new SD() { s = "1"}, new SD() { s = "2"}}
    },
    new Obj 
    { 
        p = "2",
        u = "A",
        sD = new List<SD>() {new SD() { s = "1"}}
    },
    new Obj 
    { 
        p = "1",
        u = "A",
        sD = new List<SD>() {new SD() { s = "2"}, new SD() { s = "3"}}
    }
};

var distinct = from obj in objs
               group obj by new { obj.p } into g
               select new Obj {
                   p = g.Key.p,
                   u = g.First().u, 
                   sD = g.SelectMany(i => i.sD).Distinct().ToList() 
               };

Modify class SD to use Distinct

public class SD
{
    public string s { get; set; }

    public override bool Equals(object obj)
    {
        return string.Equals(s, (obj as SD).s);
    } 

    public override int GetHashCode()
    {
        return s.GetHashCode();
    }
}

Answer 2

In this particular scenario you can use indexer to take particular List<SD> corresponding to the value you are passing to the object please go through the code that will explain it in detail;

Creation of Indexer

public List<SD> this[string index]
{
   get
     {
       foreach (Obj item in ListObj)
        {
          if (item.p == index)
          return item.sD;
        }
        return new List<SD>();
     }              
 }

In the main function you can access the indexer and store Collect the details as the follows:

    static void Main(string[] args)
    {
        ObjAssignStudy newInstance = new ObjAssignStudy();
        List<SD> sampleData=newInstance["b"];// Gives the output
       //collection as : EmptyList1,EmptyList2
    }

Complete Code for your reference is here:

 class Program
    {
        static void Main(string[] args)
        {
            ObjAssignStudy newInstance = new ObjAssignStudy();
         List<SD> sampleData=newInstance["c"];
        }
        public class SD
        {
            public string s { get; set; }
        }

        public class Obj
        {
            public string p { get; set; }
            public string u { get; set; }
            public List<SD> sD { get; set; }
        }

        public class ObjAssignStudy
        {

            private List<Obj> _ListObj= new List<Obj>();
            internal List<Obj> ListObj
            {
                get { return _ListObj; }
                set { _ListObj = value; }
            }
            List<SD> tempList = new List<SD>(); 
            public ObjAssignStudy()
            {
                tempList.Add(new SD() { s = "EmptyList1" });
                ListObj.Add(new Obj() { p = "a", sD = tempList, u = "B" });
                tempList.Add(new SD() { s = "EmptyList2" });
                ListObj.Add(new Obj() { p = "b", sD =tempList, u = "C" });
                tempList.Add(new SD() { s = "EmptyList3" });
                ListObj.Add(new Obj() { p = "c", sD =tempList, u = "D" });               
            }
            public List<SD> this[string index]
            {
                get
                {
                    foreach (Obj item in ListObj)
                    {
                        if (item.p == index)
                            return item.sD;
                    }
                    return new List<SD>();
                }              
            }
        }
    }

Test Cases: List sampleData=newInstance["a"];// Gives the output

EmptyList1

 List<SD> sampleData=newInstance["a"];// Gives the output

EmptyList1 EmptyList2

 List<SD> sampleData=newInstance["a"];// Gives the output

EmptyList1 EmptyList2 EmptyList3