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From a one to many situation how do I get common items in Entity Framework

I just started with Entity Framework and I was having difficulty generating a query for the following situation.
I currently have two model classes Student and Sport. A student can play multiple sports. This is what my models look like
public class DbContext : DbContext
{
public DbContext(): base("name=DbContext")
{
}
public DbSet<Student> MyStudents { get; set; }
public DbSet<Sport> MySports { get; set; }
}
public class Student
{
public List<Sport> Actions { get; set; }
public string Name { get; set; }
}
public class Sport
{
public string SportName { get; set; }
}
My question is how do I get a list of all sports played by all the students? In short I am looking for common sports. So basically in the following case
Student A played Sports : Soccer , Tennis , Bowling
Student B played Sports : Soccer , Tennis ,
Student C played Sport : Tennis
Then only Tennis should be returned

Using the DB schema you've provided you can get the common sports checking sports of each student:
var sports = new[]
{
new Sport { SportName = "Tennis" },
new Sport { SportName = "Soccer" },
new Sport { SportName = "Bowling" }
};
var students = new[]
{
new Student
{
Name = "Student 1",
Actions = sports
},
new Student
{
Name = "Student 2",
Actions = new[] { sports[0], sports[1] }
},
new Student
{
Name = "Student 3",
Actions = new[] { sports[0] }
}
};
// Or
var sports = context.Sports;
var students = context.Students;
// In case students' sports are objects (as in this sample) you can use such a query:
var commonSports = sports.Where(sport =>
students.All(student => student.Actions.Contains(sport)));
// In case you're going to check the sports by name, this:
var commonSports = sports.Where(sport =>
students.All(student => student.Actions.Any(studSport =>
studSport.SportName == sport.SportName)));
Console.WriteLine($"Comon sports: {string.Join(",", commonSports.Select(i => i.SportName))}");
// To get only names of common sports:
var sportNames = commonSports.Select(i => i.SportName);
Console.Read();
If you use a relational database it would be easier and (as for me) more logical to implement many-to-many relationship as described here:

var context = new DbContext()
var unique = context.MyStudents.SelectMany(student => student.Actions.Select(sport => sport.SportName)).Distinct();

you just do this :
var commonSports = Context.Students.SelectMany(x=>x.Actions).GroupBy(x => x.SportName).Where(x=>x.Count()==items.Count(c=>c.Actions!=null)).Select(x=>x.Key).ToList();
I hope it been helpful .

To achieve this you might want to first set up some kind of model class, this isn't strictly necessary but might make things clearer for you:
public class StudentWithSports()
{
public string Name {get;set;}
public List<string> Sports {get;set;}
}
You can then populate your model from your context:
using(var context = new DbContext())
{
List<StudentWithSports> list = context
.Students
.Include(stu => stu.Actions)
.Select(stu => new StudenWithSports
{
Name = stu.Name,
Sports = stu.Actions.Select(act => act.SportName).ToList()
}).ToList();
}
If you don't want to create a model you could just do:
var list = context
.Students
.Include(stu => stu.Actions)
.Select(stu => new {
Name = stu.Name,
Sports = stu.Actions.Select(act => act.SportName).ToList()
}).ToList();
Which will give you a list of anonymous objects with the same properties.

The essence of my answer is the linq query, but I created a couple of classes to model your EF classes to show it works.
Student student1 = new Student
{
Name = "John",
Actions = new List<Sport>
{
new Sport { SportName = "Tennis" },
new Sport { SportName = "Soccer" },
new Sport { SportName = "Bowling" }
}
};
Student student2 = new Student
{
Name = "Mary",
Actions = new List<Sport>
{
new Sport { SportName = "Tennis" },
new Sport { SportName = "Soccer" }
}
};
Student student3 = new Student
{
Name = "Jane",
Actions = new List<Sport>
{
new Sport { SportName = "Tennis" }
}
};
IEnumerable<Student> students = new List<Student>
{
student1,
student2,
student3
};
var query = from s in students
select new
{
s.Name,
Sports = from sp in s.Actions
select sp.SportName
};
var result = query.ToList();
for (int i = 0; i < result.Count(); i++)
{
Console.Write(result[i].Name + " played sports: ");
foreach (var sport in result[i].Sports)
Console.Write(" " + sport);
Console.WriteLine();
}

Well your Db design isn't right because you have many to many relation between MyStudents and MySports tables. You have to add joint table between Students and Sports. You can call it StudentsSports
public class DbContext : DbContext
{
public DbContext(): base("name=DbContext")
{
}
public DbSet<Student> MyStudents { get; set; }
public DbSet<StudentsSport> StudentsSports { get; set; }
public DbSet<Sport> MySports { get; set; }
}
public class Student
{
public int ID { get; set; }
public List<StudentsSport> Actions { get; set; }
public string Name { get; set; }
}
public class Sport
{
public int ID { get; set; }
public string SportName { get; set; }
}
public class StudentsSport
{
public int ID { get; set; }
[ForeignKey(Student)]
public int StudentID { get; set; }
[ForeignKey(Sport)]
public int SportID { get; set; }
}
Then you can just do
var listOfActions = MyStudents.Select(s => s.Actions.Select(a => a.SportID));
var intersection = listOfActions
.Skip(1)
.Aggregate(
new HashSet<T>(listOfActions.First()),
(h, e) => { h.IntersectWith(e); return h; }
);
EDIT:
If you have students without sports then you will always get empty intersection list. If you don't want that then you will have to filter them
var listOfActions = MyStudents.Select(s => s.Actions.Select(a => a.SportID)).Where(c => c.Any());

Issue getting different types value of self join table

I have a self join table of population. Population is entered at village level and it should be automatically calculated on Union council(UC), Tehsil and District Level.
I am using .net MVC in this application. Following is my code
enum of population type
public enum UnitType
{
Village,
UC,
Tehsil,
Dist
}
population structure, here names of villages, UC, Tehsil and district are added
public class Village
{
public int Id { get; set; }
public string Name { get; set; }
public UnitType UnitType { get; set; }
public int? ParientId { get; set; }
public Village Parient { get; set; }
}
Enter population at village level
public class Population
{
public int Id { get; set; }
public int VillageId { get; set; }
public Village Village { get; set; }
public int NoOfPerson { get; set; }
}
I need the following output result. I can get the village level population but i am confused in getting related totals. Its looks very simple but i think i am not going in right direction.
POPULATION
Code Name Type Population
1 Chakwal Disttrict 20000 (total population of all tehsils)
2 Choa Tehsil 20000 (Tehsil total of two Union Councils)
3 Dalwal UC 14300 UC is total of village population
4 Waulah Village 9800
5 DalPur VIllage 4500
Dulmial UC 5700 UC is total of village population
Tatral Village 3400
Arar Village 2300

You need to join the two classes :
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace ConsoleApplication1
{
class Program
{
const string FILENAME = #"c:\temp\test.txt";
static void Main(string[] args)
{
List<Village> villages = new List<Village>() {
new Village() { Id = 1, Name = "Chakwal", UnitType = UnitType.Dist},
new Village() { Id = 2, Name = "Choa", UnitType = UnitType.Tehsil},
new Village() { Id = 3, Name = "Dalwal", UnitType = UnitType.UC},
new Village() { Id = 4, Name = "Waulah", UnitType = UnitType.Village},
new Village() { Id = 5, Name = "DalPur", UnitType = UnitType.Village},
new Village() { Id = 6, Name = "Dulmial", UnitType = UnitType.UC},
new Village() { Id = 7, Name = "Tatral", UnitType = UnitType.Village},
new Village() { Id = 8, Name = "Arar", UnitType = UnitType.Village}
};
List<Population> populations = new List<Population>() {
new Population() { Id = 1, NoOfPerson = 20000},
new Population() { Id = 2, NoOfPerson = 20000},
new Population() { Id = 3, NoOfPerson = 14300},
new Population() { Id = 4, NoOfPerson = 9800},
new Population() { Id = 5, NoOfPerson = 4500},
new Population() { Id = 6, NoOfPerson = 5700},
new Population() { Id = 7, NoOfPerson = 3400},
new Population() { Id = 8, NoOfPerson = 2300}
};
var results = (from v in villages
join p in populations on v.Id equals p.Id
select new { v = v, p = p }
).ToList();
StreamWriter writer = new StreamWriter(FILENAME);
writer.WriteLine("{0,25}","POPULATION");
writer.WriteLine("{0,-5}{1,-8}{2,-14}{3,-10}", "Code", "Name", "Type", "Population");
foreach (var result in results)
{
writer.WriteLine("{0,-5}{1,-8}{2,-14}{3,-10}", result.v.Id.ToString(), result.v.Name, result.v.UnitType.ToString(), result.p.NoOfPerson.ToString());
}
writer.Flush();
writer.Close();
}
}
public enum UnitType
{
Village,
UC,
Tehsil,
Dist
}
public class Village
{
public int Id { get; set; }
public string Name { get; set; }
public UnitType UnitType { get; set; }
public int? ParientId { get; set; }
public Village Parient { get; set; }
}
public class Population
{
public int Id { get; set; }
public int VillageId { get; set; }
public Village Village { get; set; }
public int NoOfPerson { get; set; }
}
}

Here is the answer for the question
var villages = db.Populations.Include(l => l.Village).ToList();
var ucpop = villages.GroupBy(l => l.UCId).Select(g=> new {
ucId = g.Key,
UcName = db.Villages.Find(g.Key),
VillageCount = g.Count(),
UCPop = g.Sum(l=>l.NoOfPerson),
villages = g.Where(l=>l.Village.UnitType == UnitType.Village).ToList()
}).ToList();
var tehpop = ucpop.GroupBy(l => l.UcName.ParientId).Select(g => new
{
tehId = g.Key,
tehName = db.Villages.Find(g.Key),
tehCount = g.Count(),
tehPop = g.Sum(l => l.UCPop),
uclist = g.Where(l=>l.UcName.UnitType == UnitType.UC).ToList()
}).ToList();
var distpop = tehpop.GroupBy(l => l.tehName.ParientId).Select(g => new
{
distId = g.Key,
distName = db.Villages.Find(g.Key),
distCount = g.Count(),
distPop = g.Sum(l => l.tehPop),
tehlist = g.Where(l => l.tehName.UnitType == UnitType.Tehsil).ToList()
}).ToList();

C# - Adding data to list inside list

How can I add the following data on the table into a list called Vehicles?
public class criterias
{
public double values { get; set; }
public double time { get; set; }
}
public class movChannels
{
public string name { get; set; }
public IList<criterias> criteria = new List<criterias>();
}
public class stepsList
{
public string steps { get; set; }
public IList<movChannels> stepChannelsCriteria = new List<movChannels>();
}
public class vehicles
{
public int vehID { get; set; }
public string vehDescription { get; set; }
public IList<stepsList> vehValCriteria = new List<stepsList>();
}
Now, how can I add the data that I have in the table shown into a list called Vehicles? I will create other vehicles later...

You had several bad decisions, some were design flaws and some were minor C# naming convention violations.
Couple of worth mentions flaws:
vehID should have been a string and not int (Example "XPT")
Movment has Name, Value and Time. It doesn't have a list of Values and Times.
Creation:
List<Vehicle> vehicles = new List<Vehicle>();
Vehicle vehicle = new Vehicle()
{
Id = "XPT",
Description = "Average Car",
Steps = new List<Step>()
{
new Step() {
Name = "move car",
Movements = new List<Movement>()
{
new Movement("engage 1st gear", 1, 1),
new Movement("reach 10kph", 10, 5),
new Movement("maintain 10kph", 10, 12),
}
},
new Step() {
Name = "stop car",
Movements = new List<Movement>()
{
new Movement("reach 0kph", 10, 4),
new Movement("put in neutral", 0, 1),
new Movement("turn off vehicle", 0, 0),
}
}
}
};
vehicles.Add(vehicle);
Entities:
public class Movement
{
public string Name { get; set; }
public double Values { get; private set; }
public double Time { get; private set; }
public Movement(string name, double values, double time)
{
Name = name;
Values = values;
Time = time;
}
}
public class Step
{
public string Name { get; set; }
public IList<Movement> Movements { get; set; }
}
public class Vehicle
{
public string Id { get; set; } // Should be changed to string
public string Description { get; set; }
public IList<Step> Steps { get; set; }
}

You should create your classes like the following:
public class criterias
{
public double values { get; set; }
public double time { get; set; }
}
public class movChannels
{
public movChannels
{
criteria = new List<criterias>();
}
public string name { get; set; }
public IList<criterias> criteria { get; set; }
}
public class stepsList
{
public stepsList
{
stepChannelsCriteria = new List<movChannels>();
}
public string steps { get; set; }
public IList<movChannels> stepChannelsCriteria { get; set; }
}
public class vehicles
{
public vehicles
{
vehValCriteria = new List<stepsList>();
}
public int vehID { get; set; }
public string vehDescription { get; set; }
public IList<stepsList> vehValCriteria { get; set; }
public movChannels movments { get; set; }
}

What about that?
public class VehiclesViewModel
{
public List<vehicles> Vehicles { get; private set; }
public void Initalize()
{
this.Vehicles = new List<vehicles>();
var vehicle = new vehicles
{
vehID = 1,
vehDescription = "firstDescription",
};
var stepsList = new stepsList
{
steps = "firstStep",
};
var movChannel = new movChannels
{
name = "firstChannel",
};
var criteria = new criterias
{
values = 0.5,
time = 0.5
};
movChannel.criteria.Add(criteria);
stepsList.stepChannelsCriteria.Add(movChannel);
vehicle.vehValCriteria.Add(stepsList);
this.Vehicles.Add(vehicle);
}
}

it seems in your table the VehicleId is of type string. Make sure your VehicleId property in Vehicle class also matches the same.
You can use the collection initializers to set the values of child objects like this way:
var data = new vehicles()
{
vehID = 1,
vehDescription = "Average Car",
vehValCriteria = new List<stepsList>()
{
new stepsList()
{
steps = "Move car",
stepChannelsCriteria = new List<movChannels>()
{
new movChannels()
{
name = "engage firstgear",
criteria = new List<criterias>()
{
new criterias()
{
values = 1,
time = 1
},
}
},
new movChannels()
{
name = "reach 10kph",
criteria = new List<criterias>()
{
new criterias()
{
values = 10,
time = 5
},
}
},
new movChannels()
{
name = "maintain 10kph",
criteria = new List<criterias>()
{
new criterias()
{
values = 10,
time = 12
},
}
}
}
},
new stepsList()
{
steps = "stop car",
stepChannelsCriteria = new List<movChannels>()
{
new movChannels()
{
name = "reach okph",
criteria = new List<criterias>()
{
new criterias()
{
values = 10,
time = 4
},
}
},
new movChannels()
{
name = "put in neutral",
criteria = new List<criterias>()
{
new criterias()
{
values = 0,
time = 1
},
}
},
new movChannels()
{
name = "turn off vehicle",
criteria = new List<criterias>()
{
new criterias()
{
values = 0,
time = 0
},
}
}
}
}
}
};

You can fill your list by moving from top to bottom, like
Create Criterias List then Create movChannel object and add that list
to Criterias object and so on
However if you want to avoid this way, there is another way. If you are using Linq To List then follow this
Get a simple flat object to a list object
var TableData = db.Tablename.Tolist();
Then fill your own object like this
Vehicles finalList = TableData.Select(a => new Vehicles()
{
vehID = a.Id,
vehDescription = a.des,
vehValCriteria = TableData.Where(b => b.StepslistId == a.StepslistId)
.Select(c => new StepsList()
{
steps = c.Steps,
stepChannelsCriteria = TableData.Where(d => d.channelId == c.channelId)
.select(e => new MovChannels()
{
name = e.name,
criteria = TableData.Where(f => f.criteriasId = e.criteriasId)
.Select(g => new Criterias()
{
values = g.Values,
time = g.Time
}).ToList()
}).ToList()
}).ToList()
}).ToList();
This is standard way to fill list within list

How to use condition for all children in Entity Framework

I have these classes:
public class product
{
public int Id { get; set; }
public string Title { get; set; }
public Store Store { get; set; }
public ICollection<Color> Colors { get; set; }
}
public class Color
{
public int Id { get; set; }
public string Name { get; set; }
public product Product { get; set; }
}
public class Store
{
public int Id { get; set; }
public string Name { get; set; }
public string City { get; set; }
public ICollection<product> Products { get; set; }
}
And I have this list :
List<Store> Stores = new List<Store>
{
new Store { Id = 1, Name = "Lilo", City = "Teh",
Products = new List<product>
{
new product
{ Id = 1, Title = "Asus",
Colors = new List<Color> {
new Color { Id = 1, Name = "Blue"},
new Color { Id = 2, Name = "Orange"}
}
},
new product
{ Id = 2, Title = "Dell",
Colors = new List<Color> {
new Color { Id = 1, Name = "Yellow"},
new Color { Id = 2, Name = "Orange"},
new Color { Id = 3, Name = "Red"}
}
}
}
},
new Store{Id=2,Name="filo",City="san",
Products=new List<product>
{
new product{Id=3,Title="Asus",
Colors=new List<Color>{
new Color{Id=1,Name="Blue"},
new Color{Id=2,Name="Orange"}
}
},
new product{Id=4,Title="Dell",
Colors=new List<Color>{
new Color{Id=1,Name="Yellow"},
new Color{Id=2,Name="Lime"},
new Color{Id=3,Name="Red"}
}
}
}
}
};
I want to select all stores where Name ="Lilo" and products names is "Dell " and Color="Blue". I want do this in Entity Framework, not Linq.
I use this code but it doesn't work :
var test = Stores.Where(s => s.Name = "lilo" && s.Products.Where(p => p.Title == "Dell").FirstOrDefault().Title == "Dell" && s.Products.Where(c => c.Colors.Where(ct => ct.Name == "Blue").FirstOrDefault().Name = "Blue")).ToList();
How can I do this ?

Do this By Method Syntax :
var stlist = Stores.Where(s => s.Name.ToLower() == "lilo" && s.Products.Where(p => p.Colors.Any(c=>c.Name=="Blue") && p.Title == "Dell").FirstOrDefault().Title == "Dell").ToList();
Updated :
And Hopeless's Answers is (best answers):
var lslist2= Stores.Where(s => s.Name == "lilo" && s.Products.Any(p => p.Title == "Dell" && p.Colors.Any(c => c.Color.Name == "Blue"))).ToList();
And by Linq :
var test = (from s in Stores
from p in s.Products
from c in p.Colors
where s.Name=="Lilo" && p.Title=="Dell"&& c.Name=="Blue"
select s
).ToList();

Linq join 3 list <T>

I have three lists that I need to join together
class Person
{
public int PersonID{ get; set; }
public string FirstName{get; set;}
public string LastName {get; set;}
}
class Traffic
{
public DateTime Date{ get; set; }
public int PersonID;
public int TrafficID;
}
class TrafficType
{
public int TrafficID { get; set; }
public string Description { get; set; }
}
List<Person> Persons=GetPersons();
List<TrafficType> TrafficTypes=GetTrafficTypes();
List<Traffic> Traffics=GetTraffics();
I need an output like:
PersonID FirstName LastName Date Description
1001 David ... 2011/07/19 sample description

from person in Persons
from traffic in traffics
from trafficType in trafficTypes
where trafficType.TrafficID = traffic.TrafficID
where traffic.PersonID = person.PersonID
select new
{
PersonID = person.PersonID,
....
}

var result = Persons.Join(
Traffics,
person => person.PersonID,
trafic => trafic.PersonID,
(person, trafic) => new
{
PersonId = person.PersonID,
FirstName = person.FirstName,
LastName = person.LastName,
Date = trafic.Date,
TraficId = trafic.TrafficID
}).Join(
TrafficTypes,
a => a.TraficId,
traficType => traficType.TrafficID,
(a, traficType) => new
{
PersonId = a.PersonId,
FirstName = a.FirstName,
LastName = a.LastName,
Date = a.Date,
Description = traficType.Description
});

Here's a complete code sample with Linq query expression code that should get exactly what you're looking for:
using System;
using System.Collections.Generic;
using System.Linq;
class Person
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
class Traffic
{
public DateTime Date { get; set; }
public int PersonId { get; set; }
public int TrafficId { get; set; }
}
class TrafficType
{
public int Id { get; set; }
public string Description { get; set; }
}
class Program
{
static void Main(string[] args)
{
var persons = new List<Person>()
{
new Person()
{
Id = 1001,
FirstName = "David",
LastName = "Jones",
},
};
var trafficTypes = new List<TrafficType>()
{
new TrafficType()
{
Id = 456,
Description = "sample description",
},
};
var traffics = new List<Traffic>()
{
new Traffic()
{
PersonId = 1001,
TrafficId = 456,
Date = DateTime.Now,
},
};
var joinedData = from p in persons
from t in traffics
from tt in trafficTypes
where p.Id == t.PersonId
&& tt.Id == t.TrafficId
select new
{
PersonId = p.Id,
FirstName = p.FirstName,
LastName = p.LastName,
// Remove time component, if present
Date = t.Date.Date,
Description = tt.Description,
};
foreach (var item in joinedData)
{
Console.WriteLine("{0}\t{1}\t{2}\t{3}\t{4}"
, item.PersonId
, item.FirstName
, item.LastName
, item.Date.ToShortDateString() // Don't print the time
, item.Description
);
}
}
}
The program output is:
1001 David Jones 7/19/2011 sample description

You can put them all in a class e.g. (Problem), then use a method for your output.
class Problem
{
public Problem()
{
}
public void Show()
{
// implement your output here
}
}
Or, if you are using Windows Forms app and interisting in Tables, you can use DataGridView control. For more information about it, visit http://msdn.microsoft.com/en-us/library/e0ywh3cz.aspx
Or, use DataGrid: http://www.codeproject.com/KB/grid/usingdatagrid.aspx