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How to Select a list by having all the lists in that list

I haw this model:
public class Obj1
{
public long ID { get; set; }
public long Name { get; set; }
public List<int> NumberList { get; set; }
}
The values in Obj1 List:
List<Obj1> lst1 = new List<Obj1>();
lst1.Add(new Obj1()
{
ID = 1,
Name = "t1",
NumberList = new List<int>{1,3,4}
});
lst1.Add(new Obj1()
{
ID = 2,
Name = "t2",
NumberList = new List<int>{1,4,5}
});
lst1.Add(new Obj1()
{
ID = 3,
Name = "t3",
NumberList = new List<int>{4,5,6}
});
lst1.Add(new Obj1()
{
ID = 4,
Name = "t4",
NumberList = new List<int>{5,7,8}
});
I want to select list1 provided all list2 is in it. Also list 2 is equal to:
List<int> lst2 = new List<int>(){4,5};
I use this code, But it doesn't work properly:
var FinalList = lst1.Where(item => item.NumberList.Any(item2 => lst2.Contains(item2)).ToList();
The correct output should be this:
{
ID = 2,
Name = "t2",
NumberList = new List<int>{1,4,5}
},
{
ID = 3,
Name = "t3",
NumberList = new List<int>{4,5,6}
}

If I understand correctly, you want all Obj items in lst1 if the NumberList property is a superset of lst2. You can query this like so:
var finalList = lst1.Where(l => !lst2.Except(l.NumberList).Any()).ToList();
Full example on Ideone.

How to group a table by a certain attribute then count those elements that are present in an other table (with foreign keys) in LINQ?

Let's say I have two tables (entities):
class Person
{
public int Id { get; set; } // primary key
public string City { get; set; } // the attribute to group by
}
class JoinTable
{
public int Id { get; set; } // primary key
public int Person_Id { get; set; } // foreign key referencing a Person entity/row
public int SomeOther_Id { get; set; } // foreign key referencing some other irrelevant entity/row
}
I want to group all Person entities by their "City" attribute and count how many people are referenced in the JoinTable by each city.
How do I query that in LINQ?

I'm not quite sure, what you want to acchieve. But i think something like this:
// Example Data (would be great if you could write some in your questions..)
List<Person> ps = new List<Person>()
{
new Person() { Id = 1, City = "Cologne" },
new Person() { Id = 2, City = "Cologne" },
new Person() { Id = 3, City = "Berlin" },
new Person() { Id = 4, City = "Berlin" },
};
List<JoinTable> join = new List<JoinTable>()
{
new JoinTable() { Id = 1, Person_Id = 1, SomeOther_Id = 1000 },
new JoinTable() { Id = 1, Person_Id = 1, SomeOther_Id = 2000 },
new JoinTable() { Id = 1, Person_Id = 2, SomeOther_Id = 1000 },
new JoinTable() { Id = 1, Person_Id = 2, SomeOther_Id = 2000 },
new JoinTable() { Id = 1, Person_Id = 3, SomeOther_Id = 3000 },
new JoinTable() { Id = 1, Person_Id = 3, SomeOther_Id = 4000 },
};
// Join the Table and select a new object.
var tmp = ps.Join(
join, // which table/list should be joined
o => o.Id, // key of outer list
i => i.Person_Id, // key of inner list
(o, i) => new { City = o.City, Id = i.Id, SomeOtherId = i.SomeOther_Id}); // form a new object with three properties..
// now we can group out new objects
var groupingByCity = tmp.GroupBy(g => g.City);
// let's see what we got..
foreach (var g in groupingByCity)
{
Console.WriteLine(g.Key + ": " + g.Count());
foreach (var g2 in g.GroupBy(a => a.SomeOtherId)) // And yes we can group out values again..
{
Console.WriteLine(" " + g2.Key + ": " + g2.Count());
}
}

Cannot group data in LINQ

I have a question about a LINQ grouping.
I thought that grouping would be a simple matter of using the GroupBy function on the result set and specifying what to group it by. However my items appear to not be grouping together and instead are displaying as if the GroupBy function wasn't there. I want to group by the itemPk, but I'm can't seem to do it. I have tried grouping by both category.ItemFk and Item.Itempk, but no luck. Could someone give me a pointer on this?
var itemIds = items.Select(i => i.ItemId).ToList();
var itemAndCatJoin =
from item in Context.SCS_Items
join category in Context.SCS_ItemCategories
on item.ItemPk equals category.ItemFk
into temp
from category in temp.DefaultIfEmpty()
select new ExportItemTable
{
Category = category,
Item = item
};
return itemAndCatJoin.Where(i => itemIds.Contains(i.Item.ItemPk))
.GroupBy(n => new {n.Item, n.Category})
.Select(i => new ExportableItem
{
ItemPk = i.Key.Item.ItemPk,
Name = i.Key.Item.Name,
Description = i.Key.Item.Description,
Price = i.Key.Item.Price,
Category = i.Key.Category.Category.Category_Name,
GLDepartment = i.Key.Category.GL_Department.Name ?? "",
GLName = i.Key.Category.GL_Name.Name ?? "",
StartDate = i.Key.Item.StartDate,
EndDate = i.Key.Item.EndDate,
FiscalYear = i.Key.Item.SCS_FiscalYear.Name,
School = i.Key.Item.School != null ? i.Key.Item.School.School_Name : i.Key.Item.Board.Board_Name,
Beneficiary = i.Key.Item.SCS_Beneficiary.Name,
Quantity = i.Key.Item.MaxQuantity,
Deleted = i.Key.Item.DeletedFlag,
OptionalStudents = i.Key.Item.SCS_Attachments.Where(a => !a.IsRequired).SelectMany(a => a.SCS_StudentAttachments).Where(s => !s.DeletedFlag).Select(s => s.StudentFk).Distinct().Count(),
RequiredStudents = i.Key.Item.SCS_Attachments.Where(a => a.IsRequired).SelectMany(a => a.SCS_StudentAttachments).Where(s => !s.DeletedFlag).Select(s => s.StudentFk).Distinct().Count(),
IsPublic = i.Key.Item.IsPublic,
AllowRecurring = i.Key.Item.AllowRecurringPayments,
EffectiveCutoff = i.Key.Item.SCS_Attachments.Where(a => !a.DeletedFlag && a.CourseDropCutoff.HasValue).Select(a => a.CourseDropCutoff).OrderBy(a => a).FirstOrDefault(),
CreatedDate = i.Key.Item.CreatedDate
}).OrderBy(i => i.ItemPk).ToList();
}

your groupbyy is indeed doing nothing for you, you need to tell the groupby what to group by....
like
.GroupBy(n => n.Category)

Here is a simple example to your grouping question:
class Program
{
static void Main()
{
var allItems = GetAllItems();
var groups = from item in allItems
group item by item.Category
into newGroup
select newGroup;
foreach (var group in groups)
{
Console.WriteLine($"\nCategory: {group.Key}");
foreach (var item in group)
{
Console.WriteLine($"{item.Name}: {item.Price}");
}
}
Console.ReadLine();
}
static List<Category> GetAllCategories()
{
return new List<Category>()
{
new Category() { Id = 1, Name = "Programming Books" },
new Category() { Id = 2, Name = "Fiction Books" }
};
}
static List<Item> GetAllItems()
{
return new List<Item>()
{
new Item() { Id = 1, Name = "Embedded Linux", Category = 1, Price = 9.9 },
new Item() { Id = 2, Name = "LINQ In Action", Category = 1, Price = 36.19 },
new Item() { Id = 3, Name = "C# 6.0 and the .NET 4.6 Framework", Category = 1, Price = 40.99 },
new Item() { Id = 4, Name = "Thinking in LINQ", Category = 1, Price = 36.99 },
new Item() { Id = 5, Name = "The Book Thief", Category = 2, Price = 7.99 },
new Item() { Id = 6, Name = "All the Light We Cannot See", Category = 2, Price = 16.99 },
new Item() { Id = 7, Name = "The Life We Bury", Category = 2, Price = 8.96 }
};
}
}
public class Item
{
public int Id { get; set; }
public string Name { get; set; }
public double Price { get; set; }
public int Category { get; set; }
}
public class Category
{
public int Id { get; set; }
public string Name { get; set; }
}
This example is simple enough for anyone new to LINQ. I am sure you can make some adjustment to make it work for your specific issue. Hope this will help.

LINQ group list and combine collections

Given these classes:
public class Employee
{
public int EmployeeId { get; set; }
public int GroupId { get; set; }
public List<Plans> Plans { get; set; }
}
public class Plan
{
public int PlanYearId { get; set; }
public string Name { get; set; }
}
And given a setup like so:
var employees = new List<Employee> {
new Employee {
EmployeeId = 1,
GroupId = 1,
Plans = new List<Plan> {
new Plan {
PlanReferenceId = 1111,
Name = "Benefit 1"
}}};
new Employee {
EmployeeId = 1,
GroupId = 1,
Plans = new List<Plan> {
new Plan {
PlanReferenceId= 2222,
Name = "Benefit 2"
},
new Plan {
PlanReferenceId= 2222,
Name = "Benefit 3"
}}}};
How can I use LINQ to group these employees by both EmployeeId and GroupId and then combine the two List<Plan> properties so that i would end up with something like this:
var employee = new Employee
{
EmployeeId = 1,
GroupId = 1,
Plans = new List<Plan> {
new Plan {
PlanReferenceId = 1111,
Name = "Benefit 1"
},
new Plan {
PlanReferenceId = 2222,
Name = "Benefit 2"
},
new Plan {
PlanReferenceId = 2222,
Name = "Benefit 3"
}
}
}

Just use combination of GroupBy and SelectMany:
var result = employees
.GroupBy(e => new { e.EmployeeId, e.GroupId })
.Select(g => new Employee
{
EmployeeId = g.Key.EmployeeId,
GroupId = g.Key.GroupId,
Plans = g.SelectMany(e => e.Plans).ToList()
}).ToList();

Flat Data to Hierarchical Model C#

I have some flat data coming from the database that looks like this:
List<FlatDataGroup> elements = new List<FlatDataGroup>()
{
new FlatDataGroup {Text = "", GroupID = 1, ParentGroupID = 0, GroupName = "Admin", UserID = 1, UserName = "John Doe"},
new FlatDataGroup {Text = "", GroupID = 1, ParentGroupID = 0, GroupName = "Admin", UserID = 2, UserName = "Jane Smith"},
new FlatDataGroup {Text = "", GroupID = 2, ParentGroupID = 1, GroupName = "Support", UserID = 3, UserName = "Johnny Support"},
new FlatDataGroup {Text = "", GroupID = 3, ParentGroupID = 2, GroupName = "SubSupport", UserID = 4, UserName = "Sub Johnny Support"},
new FlatDataGroup {Text = "", GroupID = 4, ParentGroupID = 1, GroupName = "Production", UserID = 5, UserName = "Johnny Production"}
};
I would like to convert it to this:
List<Group> model = new List<Group>
{
new Group()
{
ID = 1,
Name = "Admin",
ParentGroupID = 0,
Type = "Group",
Users = new List<User>()
{
new User()
{
ID = 1,
Name = "John Doe",
GroupID = 1,
Type = "User",
},
new User()
{
ID = 2,
Name = "Jane Smith",
GroupID = 1,
Type = "User",
},
},
Groups = new List<Group>
{
new Group()
{
ID = 2,
Name = "Support",
ParentGroupID = 1,
Type = "Group",
Users = new List<User>()
{
new User()
{
ID = 3,
Name = "Johnny Support",
GroupID = 2,
Type = "User",
}
},
Groups = new List<Group>()
{
new Group()
{
ID = 3,
Name = "SubSupport",
ParentGroupID = 2,
Type = "Group",
Users = new List<User>()
{
new User()
{
ID = 4,
Name = "Sub Johnny Support",
GroupID = 3,
Type = "User",
}
},
Groups = null
}
}
},
new Group()
{
ID = 4,
Name = "Production",
ParentGroupID = 1,
Type = "Group",
Users = new List<User>()
{
new User()
{
ID = 5,
Name = "Johnny Production",
GroupID = 4,
Type = "User",
}
},
Groups = null
}
}
}
};
which will ultimately display like this in a treeview:
+Admin (Group)
John Doe (User)
Jane Smith (User)
+Support (Group)
Johnny Support (User)
+SubSupport (Group)
Sub Johnny Support (User)
+Production (Group)
Johnny Production (User)
This is what I've come up with so far to transform the flat data into the model above:
List<Group> model = new List<Group>();
var parentGrouping = elements.GroupBy(x => x.ParentGroupID);
foreach (var parentGroup in parentGrouping)
{
var grouping = parentGroup.GroupBy(y => y.GroupID);
foreach (var group in grouping)
{
Group groupItem = new Group()
{
ID = group.FirstOrDefault().GroupID,
Name = group.FirstOrDefault().GroupName,
ParentGroupID = group.FirstOrDefault().ParentGroupID,
Type = "Group",
Users = new List<User>()
};
foreach (var user in group)
{
groupItem.Users.Add(new User()
{
ID = user.UserID,
Name = user.UserName,
GroupID = user.GroupID,
Type = "User",
});
}
model.Add(groupItem);
}
}
All my groups come out along with their children users but the hierarchy is not preserved. I think I may need to do this recursively but I can't seem to get my head around it. Any help would be greatly appreciated.
Here are the models for the sake of completeness:
public class FlatDataGroup
{
public string Text { get; set; }
public int GroupID { get; set; }
public int ParentGroupID { get; set; }
public string GroupName { get; set; }
public int UserID { get; set; }
public string UserName { get; set; }
}
public class Group
{
public int ID { get; set; }
public int ParentGroupID { get; set; }
public string Name { get; set; }
public List<Group> Groups { get; set; }
public List<User> Users { get; set; }
public string Type { get; set; }
}
public class User
{
public int ID { get; set; }
public int GroupID { get; set; }
public string Name { get; set; }
public string Type { get; set; }
}

I'd do this in 3 passes:
Create all Group classes and populate them with data other than child groups, adding them incrementally to a dictionary mapping ID to Group.
Loop through all the groups in the dictionary and add children to their parents' Groups list of children.
Return a filtered list of all groups with no parent group -- these are the root groups. (I also sorted them by ID to remove the random ordering that the dictionary will introduce.)
Thus:
public static class FlatDataGroupExtensions
{
public const string UserType = "User";
public const string GroupType = "Group";
public static List<Group> ToGroups(this IEnumerable<FlatDataGroup> elements)
{
// Allocate all groups and index by ID.
var groups = new Dictionary<int, Group>();
foreach (var element in elements)
{
Group group;
if (!groups.TryGetValue(element.GroupID, out group))
groups[element.GroupID] = (group = new Group() { ID = element.GroupID, Name = element.GroupName, ParentGroupID = element.ParentGroupID, Type = GroupType });
group.Users.Add(new User() { GroupID = element.GroupID, ID = element.UserID, Name = element.UserName, Type = UserType });
}
// Attach child groups to their parents.
foreach (var group in groups.Values)
{
Group parent;
if (groups.TryGetValue(group.ParentGroupID, out parent) && parent != group) // Second check for safety.
parent.Groups.Add(group);
}
// Return only root groups, sorted by ID.
return groups.Values.Where(g => !groups.ContainsKey(g.ParentGroupID)).OrderBy(g => g.ID).ToList();
}
}
I also modified your Group class a little to automatically allocate the lists:
public class Group
{
List<Group> groups = new List<Group>();
List<User> users = new List<User>();
public int ID { get; set; }
public int ParentGroupID { get; set; }
public string Name { get; set; }
public string Type { get; set; }
public List<Group> Groups { get { return groups; } }
public List<User> Users { get { return users; } }
public override string ToString()
{
return string.Format("Group: ID={0}, Name={1}, Parent ID={2}, #Users={3}, #Groups={4}", ID, Name, ParentGroupID, Users.Count, Groups.Count);
}
}