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group by and merge some field result in linq

I have a class like
public class Person
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
Now I have a list of this class: List<Person> persons;
var persons = new List<Person> {
new Person { Id = 1, LastName = "Reza", FirstName="Jenabi" },
new Person { Id = 1, LastName = "Amin", FirstName="Golmahalle"},
new Person { Id = 2, LastName = "Hamed", FirstName="Naeemaei"}
};
Is there a way I can group by Id and get the list of all the full Name (Combine first and last names)?
So after grouping:
var Id = results[0].Id; // Output : 1
List<string> fullNames = results[0].FullNames; // Output : "Reza Jenabi","Amin Golmahalle"

I believe this is what you need:
var results = persons.GroupBy(x => x.Id)
.Select(x => new { Id = x.Key, FullNames = x.Select(p => $"{p.FirstName} {p.LastName}").ToList() })
.ToList();

I think bellow code can help you:
var fff = from p in persons
group $"{p.FirstName} {p.LastName}" by p.Id into g
select new { PersonId = g.Key, FullNames = g.ToList() };

yeah, you can use GroupBy and Join those items:
var grouped = persons.GroupBy(p => p.Id)
.Select(s => string.Join(", ", s.Select(a=> $"{a.FirstName} {a.LastName}")));

Converting list from one class to another

I'm trying to convert a group a complex list in C# (with Linq)
public class classA
{
public string Name { get; set; }
public int id { get; set; }
public string phone { get; set; }
public string interest { get; set; }
}
My first class is classA where it contains many list of elements like below.
List<classA> obj = new List<classA>();
obj.Add(new classA { id = 1, Name = "a", phone = "321", interest = "Playing" });
obj.Add(new classA { id = 1, Name = "2", phone = "123", interest="Tv" });
From this I need to group by using the id, So I've used Linq
var item = obj.GroupBy(a => a.id).Select(ac => ac.ToList()).ToList();
I've another class called classB which hold's the values others than id from the classA (where it'd be hold all subset of different attributes)
public class classB
{
public string Name { get; set; }
public string phone { get; set; }
public string interest { get; set; }
}
My Final Class looks likes,
public class Final
{
public int id { get; set; }
public List<classB> details { get; set; }
public Final()
{
details = new List<classB>();
}
}
My requirements are, after grouping the classA based on id, I need to convert that into my final class.
So I did like below,
public static void Main()
{
Console.WriteLine("Hello World");
List<classA> obj = new List<classA>();
obj.Add(new classA { id = 1, Name = "a", phone = "321", interest = "Playing" });
obj.Add(new classA { id = 1, Name = "b", phone = "123", interest = "Tv" });
obj.Add(new classA { id = 2, Name = "c", phone = "12322", interest = "Tv" });
obj.Add(new classA { id = 3, Name = "d", phone = "12333", interest = "Tv" });
var item = obj.GroupBy(a => a.id).Select(ac => ac.ToList()).ToList();
List<Final> finalobjList = new List<Final>();
foreach (var report in item)
{
Final finalObj = new Final();
foreach (var result in report)
{
finalObj.id = result.id;
}
var data = report.Select(x => new classB { Name = x.Name, phone = x.phone, interest = x.interest }).ToList();
finalObj.details = data;
finalobjList.Add(finalObj);
}
Console.WriteLine(finalobjList.Count());
}
I believe there is another easy way to achieve this using linq without using foreach multiple times
Appreciate your help!

You should be able to use your existing code except when you do your Select, select a new Final and use the group's Key for the Id, and convert the ac.ToList to a list of ClassB for the Details:
var item = obj
.GroupBy(a => a.id)
.Select(ac =>
new Final
{
Id = ac.Key,
Details = ac.Select(a =>
new classB {interest = a.interest, phone = a.phone, Name = a.Name})
.ToList()
});

var finalobjList = obj.GroupBy(a => a.id).Select(x => new Final() { id = x.Key, details = x.Select(y => new classB() { Name = y.Name }).ToList() } ).ToList();
(Code only answer - please dont hate me)

var items = (from a in obj
group new classB {Name = a.Name, phone = a.phone, interest = a.interest} by a.id into aa
select new Final { id = aa.Key, B= aa.ToList()}).ToList();

Updating a list based on another list

I have two lists of users.
In the first the users have the following fields - fname,lname, UserDetailsId,FocusStart,FocusEnd,isActive
In the second list the users have - fname, lname, UserDetailsId,totalTime, FocusStart, FocusEnd.
What I am aiming to do is : when the value isActive from the first list equals to 'true' and the userDetailsId equeals UserDetailsId from the second list I want the FocusStart and FocusEnd in the second list to be equals to the values of the matched element in the first list.
Any tips on how to achieve this?
Here is how I get the first list :
var list = listWRUD.
Join(db.UsersDetails,
o => o.UserDetailsId, od => od.identtyUserId,
(o, od) => new
{
fname = od.FirstName,
lname = od.LastName,
UserDetailsId = o.UserDetailsId,
FocusStart = o.FocusStart,
FocusEnd = o.FocusEnd,
isActive = o.isActive
}).ToList();
var a = from x in list
group x by new { x.fname, x.lname, x.UserDetailsId } into g
select new RolesUsersViewModel(g.Key.UserDetailsId, g.Key.fname, g.Key.lname, TimeSpan.FromMilliseconds(g.Sum(x => (x.FocusEnd - x.FocusStart).TotalMilliseconds)));
And here is the second one :
List<RolesUsersViewModel> list_users = a.ToList<RolesUsersViewModel>();
What i've got so far is :
var allActive = list.Where(item => item.isActive == true);
foreach (var p in list_users.Join(allActive, item => item.userId, item => item.UserDetailsId, (x, y) => new { L2 = x, L1 = y }))
{
p.L2.FocusStart = p.L1.FocusStart;
p.L2.FocusEnd = p.L1.FocusEnd;
}
Sadly, this code seems to give me some random results. A date is set to the records in the second list even if there are no records with isActive==true in the first.
The ViewModel :
public class RolesUsersViewModel
{
public RolesUsersViewModel(string userDetailsId, string FirstName, string LastName, TimeSpan totalex)
{
userId = userDetailsId;
fname = FirstName;
lname = LastName;
total = totalex;
}
public RolesUsersViewModel(DateTime focusStart, DateTime focusEnd)//
{
FocusStart = focusStart;
FocusEnd = focusEnd;
}
public string userId { get; set; }
public string fname { get; set; }
public string lname { get; set; }
public TimeSpan total { get; set; }
public DateTime FocusStart { get; set; }//
public DateTime FocusEnd { get; set; }//
}

foreach (var p in list_users)
{
// Get all the items that have matching UserDetailsId
var targets = allActive.Where(x => x.UserDetailsId == p.UserDetailsId);
// Now assign the properties
// my assumption is that the above query should return
// a single record. If my assumption is true then use
// Single or SingleOrDefault and then you do not need
// the loop below but just a simple assignment
foreach(var thisTarget in targets)
{
p.FocusStart = thisTarget.FocusStart;
p.Focused = thisTarget.FocusEnd;
}
}

Linq expression to fill model containing other List<T>

I have a model (sample below), and sample data with desired output..
I have also given two ways to populate model which will give desired output but for somereason,
looks like I am missing something....
Not able to figure out what is the issue here...
need inputs in correcting approach 1 or approach 2 or you can also suggest any other approach which will help populate model in below response..
models
class Emp
{
public int id {get;set;}
public int Name {get;set;}
public List<cardType> cardTypes {get;set;}
}
class cardType
{
public int name {get;set;}
public DateTime Expiry {get;set;}
}
sample data (Data is returned in 1 table only)
id Name cardTypeName exp
1 a Amex 1010
1 a City 2010
desired output
<Emp>
<ID>1</id>
<name>1</name>
<cardTypes>
<cardType>
<Name> Amex </Name>
<exp> 1010 </exp>
</cardType>
<cardType>
<Name> City </Name>
<exp> 2010 </exp>
</cardType>
<cardTypes>
</Emp>
approach 1
(dataTable.AsEnumerable()
.GroupBy(r => r.ItemArray[1])
.Select(grp => new Emp()
{
id = r.itemarray[1],
name = r.itemarray[1],
cardTypes = grp.Select(t => new cardType()
{
field 1,
field 2
}).ToList()
}));
approach 2
return (from DataRow dr in dataTable.Rows
select new Emp
{
id = "",
name= "",
cardTypes = dataTable.AsEnumerable()
.Select(x => new cardType
{
name = ""
exp = ""
}).ToList(),
});

try this
return dataTable.AsEnumerable()
.GroupBy(x => x.Id)
.Select(x => new
{
id = x.Key,
name = x.Key,
cardTypes = x.Select(t => new
{
name = t.Name,
exp = t.Exp
})
});

This should work for you considering you will change the Expiry field in cardType to int
var results =
dt.AsEnumerable()
.GroupBy(row => row.ItemArray[0])
.Select(rows => new Emp
{
id = rows.Key,
name = rows.Key,
cardTypes = rows.Select(row => new cardType {Name = row.ItemArray[2], Expiry = row.ItemArray[3]})
});
If you desire to have DateTime, then decide how to convert. For example:
cardTypes = rows.Select(row => new cardType {Name = row.ItemArray[2], Expiry = new DateTime(row.ItemArray[3],1,1)})

If you want to serialize to xml your models, you should mark your models with [Serializable] attribute and just use XmlSerializer.
[Serializable]
class Emp
{
public int id {get;set;}
public int Name {get;set;}
public List<cardType> cardTypes {get;set;}
}
[Serializable]
class cardType
{
public int name {get;set;}
public DateTime Expiry {get;set;}
}
After that you can use following code:
static Dictionary<int, Emp> ConvertToDict(DataTable dt)
{
Dictionary<int, Emp> emps = new Dictionary<int, Emp>();
foreach (var dr in dt.AsEnumerable())
{
var id = (int)dr["ID"];
var name = (string)dr["Name"];
var cardTypeName = (string)dr["CardTypeName"];
var exp = (int)dr["Exp"];
Emp emp;
var cardType = new CardType { Name = cardTypeName, Exp = exp };
if (emps.TryGetValue(id, out emp))
{
emp.CardTypes.Add(cardType);
}
else
{
emps.Add(id, new Emp { ID = id, Name = name, CardTypes = new List<CardType> { cardType } });
}
}
return emps;
}
static List<string> Serialize<T>(IEnumerable<T> entities) where T:new()
{
var ser = new XmlSerializer(typeof(T));
var serializedEntities = entities.Select(entity =>
{
using (var sw = new StringWriter())
{
ser.Serialize(sw, entity);
return sw.ToString();
}
}).ToList();
return serializedEntities;
}

using Linq to break flat table results into object collection

I have a database return result which has flatten results like below. I want to use Linq to break the flat results into primary classes with the items populating the primary class items property collection.
public class Result
{
public string PrimaryKey { get; set; }
public string Status { get; set; }
public string ItemName { get; set; }
}
public class ObjectA
{
public string PrimaryKey { get; set; }
public string Status { get; set; }
public List<Item> Items = new List<Item>();
}
public class Item
{
public string Name { get; set; }
}
static void Main(string[] args)
{
GetObjectAs();
}
static List<ObjectA> GetObjectAs()
{
// this is our table results
List<Result> results = new List<Result>();
results.Add(new Result()
{
PrimaryKey = "1",
Status = "Done",
ItemName = "item1"
});
results.Add(new Result()
{
PrimaryKey = "2",
Status = "Fail",
ItemName = null
});
results.Add(new Result()
{
PrimaryKey = "3",
Status = "Done",
ItemName = "item2"
});
results.Add(new Result()
{
PrimaryKey = "3",
Status = "Done",
ItemName = "item3"
});
List<ObjectA> returnResults = new List<ObjectA>();
// need to break into 3 ObjectA objects
// ObjectA 1 needs an Item added to its Items collection with ItemName item1
// ObjectA 2 has no items since the ItemName above is null
// ObjectA 3 needs 2 Items added to its Items collection item2 and item3
// return our collection
return returnResults;
}
PS this is just sample code, I know you shouldn't expose a List as a public property and should return an IEnumerator instead of the actual List etc.

You can use GroupBy to group the results by the primary key, then you can operate on the subset of rows within the group to obtain the status (hopefully all values for Status are the same, which is why I used First) and the list of items.
var items = results.GroupBy(r => r.PrimaryKey).Select(grp => new ObjectA()
{
PrimaryKey = grp.Key,
Status = grp.Select(r => r.Status).First(),
Items = grp.Where(r => r.ItemName != null)
.Select(r => new Item() { Name = r.ItemName }).ToList()
}).ToList();

return results
.GroupBy(r => r.PrimaryKey)
.Select(grp => new ObjectA
{
PrimaryKey = grp.Key,
Status = grp.First().Status,
Items = grp.Where(i => i.ItemName != null).Select(i => new Item { Name = i.ItemName }).ToList()
}).ToList();