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C# list sort with OR condition

I'm trying to sort a list that comes from my database. If all fields in my OrderFunds column are null, I want to sort by another column. Can anyone tell me how to do this?
This is my code:
List<Fund> funds = await fundSupervisor.List().Where(fund => fund.IsActive)
.OrderBy(fund => fund.OrderFunds)
Or, my OrderBy clause can allow null values. That would help me too.

This is the solution
List<Fund> funds = fundSupervisor
.Where(w => w.IsActive)
.OrderBy(w => w.OrderFunds)
.ThenBy(w => w.OtherField).ToList();
ThenBy() allows you specify other fields to sort your list.

If you need to sort totally different if, and only if all columns are null, you need to check that in advance.
List<Fund> funds = await fundSupervisor.List().Where(fund => fund.IsActive)
if(funds .Any(item => item.OrderFunds != null))
funds = funds.OrderBy(fund => fund.OrderFunds);
else
funds = funds.OrderBy(fund => fund.SomethingElse);
Otherwise, if you want to sort by another value if OrderFunds is null, then you can simply use a condition inside the OrderBy.
var orderedFunds = funds.OrderBy(fund => fund.OrderFunds ?? SomeOtherValue);
If you want to sort by another value as secondary sorting, use a ThenBy. That sorts all values by the ThenBy-value if there are multiple same values in the OrderBy-operation.
var orderedThenByFunds = funds.OrderBy(fund => fund.OrderFunds).ThenBy(fund => fund.SomeOtherValue);
Consider that these lines are different:
Say you have 3 items (assumed OrderFunds is int?:
Fund1 { OrderFunds = 1, SomeOtherValue = 8 }
Fund2 { OrderFunds = 3, SomeOtherValue = 6 }
Fund3 { OrderFunds = null, SomeOtherValue = 4 }
Fund4 { OrderFunds = null, SomeOtherValue = 2 }
Then orderedFunds would return Fund1(1), Fund4(2[SomeOtherValue]), Fund2(3), Fund3(4[SomeOtherValue]) and orderedThenByFunds would return Fund1(1,8), Fund2(3,8), Fund4(null,2), Fund3(null,2). The values in braces are the values ordered by.

Using linq to group and sum List<int> (Zip?)

I have a list of objects I want to group.
Objects have a List parameter, and during grouping I want to make the sum of the lists like this :
for(int i=0;i<MyList1.Count();i++)
{
StatutOperations[i]=StatutOperations1[i]+StatutOperations2[i]...
}
For now using linq I have the following :
liste_rep = liste_rep.GroupBy(l => l.Nom)
.Select(cl => new Repere
{
Quantite = cl.Sum(c => c.Quantite),
IdAff = cl.First().IdAff,
ID = 0,
ListeOperations = cl.First().ListeOperations,
StatutOperations = cl.Zip(StatutOperations)//First().StatutOperations
}).ToList();
The line making problem is the last one, I found how to use Zip function to summ two tables, but what if I want to use it grouping Lists?
Edit : StatusOperations is a list of integers, concretely liste_rep is a list of details, details have a list of n operations, and StatusOperations determines how much details have been operated for each operation.
Example :
ListOperations = CUT, DRILL, PAINT
StatusOperations = 20,20,10
This means 20 details are cut, 20 are drilled and 10 are painted
I want to group the list of details getting totals for each operation.
Edit 2 :
For now I only could manage to do it making myself the grouping :
liste_rep = liste_rep.OrderBy(p => p.Nom).ToList();
if (liste_rep.Count()>1)
{
totalStatut = liste_rep[0].StatutOperations.ConvertAll(s => s = 0);
string oldRep = "";
Repere repere = new Repere();
foreach (Repere rep in liste_rep)
{
if (rep.Nom!=oldRep)
{
newListRep.Add(repere);
repere = new Repere();
repere.Nom = rep.Nom;
repere.StatutOperations = rep.StatutOperations;
}
else
{
repere.StatutOperations=repere.StatutOperations.Zip(rep.StatutOperations, (x, y) => x + y).ToList();
}
oldRep = rep.Nom;
}
}

You can use this
if StatutOperations is a list of int).
Use this at last line.
StatutOperations= cl.Aggregate((opl1, opl2) =>
{ return opl1.StatutOperations.Zip(opl2.StatutOperations, (opin1,opin2)=>opin1+opin2).ToList(); });
in above code Aggregate runs through two elements and aggregate as sum (op1+op2).
Note : Remember use aggregate if and only if list contains more than one element
.
Edit:
Sorry the above code is incorrect as this is applying aggregate on repere type object and hence the expected return value would be of Repere type.
Edited my code now it should work fine now.
liste_rep.GroupBy(l => l.Nom)
.Select(cl => new Repere
{
Quantite = cl.Sum(c => c.Quantite),
IdAff = cl.First().IdAff,
ID = 0,
ListeOperations = cl.First().ListeOperations,
StatutOperations = cl
.Select(x=>x.StatutOperations)
.Aggregate((x,y)=> x.Zip(y,(p,q)=>p+q).ToList());
}).ToList();

Can't Concatenate String in LINQ query

I am just trying to concatenate a string on to a column returned from the database like so:
var aaData =
(from pr in ctx.PaymentRates
where pr.ServiceRateCodeId == new Guid("BBCE42CB-56E3-4848-B396-4656CCE3CE96")
select new
{
Id = pr.Id,
Rate = pr.YearOneRate + "helloWorld"
})
.ToList();
It gives me this error:
Unable to cast the type 'System.Nullable`1' to type 'System.Object'.
LINQ to Entities only supports casting EDM primitive or enumeration
types.
So, then I tried this:
var aaData =
(from pr in ctx.PaymentRates
where pr.ServiceRateCodeId == new Guid("BBCE42CB-56E3-4848-B396-4656CCE3CE96")
select new
{
pr = pr
})
.AsEnumerable()
.Select(x => new
{
Id = x.pr.Id,
Rate = x.pr.YearOneRate + "helloWorld"
})
.ToList();
But, now it gives me this error:
Object reference not set to an instance of an object.
On this line:
.Select(x => new
How can I concatenate these strings in LINQ?

The quick solution
Regarding your second code chunk I need to point out to you that you're actually doing two left outer joins on the Countries table/set, one for homeC and one for hostC.
That means that you are willing to accept null values for those two variables.
In other words, since they can be null you are somehow allowing this right here to crash with NullReferenceException, should those variables turn out to be null:
.Select(x => new
{
Id = x.pr.Id,
HomeCountry = x.homeC.Name,
HostCountry = x.hostC.Name,
Rate = x.pr.YearOneRate + "helloWorld"
})
The error (NullReferenceException or as you saw it's message: "Object reference not set to an instance of an object.") is not here
.Select(x =>
but rather here
x.homeC.Name and x.hostC.Name
where you will most certainly dereference a null reference.
That's just Visual Studio's way of pointing out the best statement that fits around the error.
So, the quickest solution would be to do this:
.Select(x => new
{
Id = x.pr.Id,
HomeCountry = (x.homeC != null) ? x.homeC.Name : "HomeCountry not found",
HostCountry = (x.hostC.Name != null) ? x.hostC.Name : "HostCountry not found",
Rate = x.pr.YearOneRate + "helloWorld"
})
Notice the modification which ensures that you will still be able to extract some information from result set records for which homeC and hostC are null.
EDIT
Regarding the first query you posted:
var aaData =
(from pr in ctx.PaymentRates
where pr.ServiceRateCodeId == new Guid("BBCE42CB-56E3-4848-B396-4656CCE3CE96")
select new
{
Id = pr.Id,
Rate = pr.YearOneRate + "helloWorld"
})
.ToList();
my guess is that your 'YearOnRate' property is of type 'Nullable< of something >" (maybe decimal -- so for instance it is maybe a decimal? YearOnRate { get; set; }) and the corresponding column in the database is a nullable one.
If that is the case, then I think (in this first version of your endeavour) you could try to do this:
Rate = (pr.YearOnRate != null) ? pr.YearOneRate.Value + "helloWorld" : "[null]helloWorld"
and get away with it.

My guess is that either x.homeC, x.hostC, or x.pr are null. If you're fine using AsEnumerable to convert to Linq-to-Objects then you could just change your projection to
.Select(x => new
{
Id = (x.pr.HasValue ? x.pr.Id : 0),
HomeCountry = (x.homeC.HasValue ? x.homeC.Name : null),
HostCountry = (x.hostC.HasValue ? x.hostC.Name : null),
Rate = (x.pr.HasValue ? x.pr.YearOneRate : null) + "helloWorld"
})

My problem was, I wasn't using .AsEnumerable() properly. The code below works:
var aaData =
(from pr in ctx.PaymentRates
from homeC in ctx.Countries.Where(x => x.Id == pr.HomeCountryId).DefaultIfEmpty()
from hostC in ctx.Countries.Where(x => x.Id == pr.HostCountryId).DefaultIfEmpty()
from curr in ctx.Currencies.Where(x => x.Id == pr.YearOneCurrencyId).DefaultIfEmpty()
where pr.ServiceRateCodeId.Value.Equals(new Guid("BBCE42CB-56E3-4848-B396-4656CCE3CE96"))
select new { pr, homeC, hostC, curr })
.AsEnumerable()
.Select(x => new
{
Id = (string)(x.pr.Id.ToString() + "test"),
HomeCountry = (x.homeC != null ? x.homeC.Name : ""),
HostCountry = (x.hostC != null ? x.hostC.Name : ""),
Rate = (x.pr.YearOneRate ?? 0) + " (" + x.curr.Code + ")"
})
.ToList();

You have used DefaultIfEmpty on both homeC and hostC so you can get a null reference when you call homeC.Name or hostC.Name
Try using HomeCountry = homeC == null ? null : homeC.Name instead
If pr.YearOneRate is not a string and you want the concatenation done by the database engine you need to tell Linq-to-Entities to generate sql to convert it. If you are using Sql Server you can use this:
SqlFunctions.StringConvert(pr.YearOneRate) + "helloWorld"
If you don't need the concatenation done in the database then you can use AsEnumerable() before the Select so that you are running Linq-To-Objects

Create a new anonymous type list to union onto existing anonymous type list

I have a list of anonymous types that I get from my database:
var takenChannels = (from b in bq.GetStuff(db)
where b.RecordType == "H" && b.TourStartDateTime.Date == date
select new { Start = b.TourStartDateTime, End = b.TourEndDateTime, Channel = b.RadioChannel, TourArea = b.TourArea }).ToList();
Then I use this list info to do some stuff in a foreach loop. I want to add to this list a new anonymous item for when I come back round in the loop.
Something like:
takenChannels.Union{new[] { new{Start = DateTime.Now, End = DateTime.Now.AddDays(1), Channel = 25, TourArea = "Area" }});
Obviously this doesn't work. How do I do it?
Edit 1:
takenChannels.Add(new { Start = s, End = e, Channel = channel, TourArea = booking.TourArea });
This is the closest I've got so far (Thanks to Daniel)... but the error I get is:
Error 6 Argument 1: cannot convert from 'AnonymousType#2' to 'AnonymousType#1'

This answer might be a bit late, but since this is the question I found when Googling for the same problem, I think I should complete it with a working answer.
There is no problem to Union multiple times over anonymous types. It is important that all properties are declared in all instances and that they have the same data type. if not, you get the error above.
In your specific case, does the database perhaps return TourStartDateTime or TourEndDateTime as DateTime??
Is RadioChannel an int from the database or perhaps an int? or string?
Is TourArea a string in the database?
Just make sure the data types match and you should be fine. Below is a working snippet of code I use in my own program:
var regions = (
new[] { new { Id = "-1", Name = "---", Pattern = (string)null } }
).Union(
from x in db.Userlists where x.ListType == 2 select new { Id = x.UserlistID.ToString(), Name = x.Name, Pattern = (string)null }
).Union(
from x in db.Lookups where x.Category == "Stock" select new { Id = x.Key, Name = x.Key, Pattern = x.Value }
).ToArray();

You can simply Add to the list:
takenChannels.Add(new { Start = ... });

Use LINQ to group a sequence by date with no gaps

I'm trying to select a subgroup of a list where items have contiguous dates, e.g.
ID StaffID Title ActivityDate
-- ------- ----------------- ------------
1 41 Meeting with John 03/06/2010
2 41 Meeting with John 08/06/2010
3 41 Meeting Continues 09/06/2010
4 41 Meeting Continues 10/06/2010
5 41 Meeting with Kay 14/06/2010
6 41 Meeting Continues 15/06/2010
I'm using a pivot point each time, so take the example pivot item as 3, I'd like to get the following resulting contiguous events around the pivot:
ID StaffID Title ActivityDate
-- ------- ----------------- ------------
2 41 Meeting with John 08/06/2010
3 41 Meeting Continues 09/06/2010
4 41 Meeting Continues 10/06/2010
My current implementation is a laborious "walk" into the past, then into the future, to build the list:
var activity = // item number 3: Meeting Continues (09/06/2010)
var orderedEvents = activities.OrderBy(a => a.ActivityDate).ToArray();
// Walk into the past until a gap is found
var preceedingEvents = orderedEvents.TakeWhile(a => a.ID != activity.ID);
DateTime dayBefore;
var previousEvent = activity;
while (previousEvent != null)
{
dayBefore = previousEvent.ActivityDate.AddDays(-1).Date;
previousEvent = preceedingEvents.TakeWhile(a => a.ID != previousEvent.ID).LastOrDefault();
if (previousEvent != null)
{
if (previousEvent.ActivityDate.Date == dayBefore)
relatedActivities.Insert(0, previousEvent);
else
previousEvent = null;
}
}
// Walk into the future until a gap is found
var followingEvents = orderedEvents.SkipWhile(a => a.ID != activity.ID);
DateTime dayAfter;
var nextEvent = activity;
while (nextEvent != null)
{
dayAfter = nextEvent.ActivityDate.AddDays(1).Date;
nextEvent = followingEvents.SkipWhile(a => a.ID != nextEvent.ID).Skip(1).FirstOrDefault();
if (nextEvent != null)
{
if (nextEvent.ActivityDate.Date == dayAfter)
relatedActivities.Add(nextEvent);
else
nextEvent = null;
}
}
The list relatedActivities should then contain the contiguous events, in order.
Is there a better way (maybe using LINQ) for this?
I had an idea of using .Aggregate() but couldn't think how to get the aggregate to break out when it finds a gap in the sequence.

Here's an implementation:
public static IEnumerable<IGrouping<int, T>> GroupByContiguous(
this IEnumerable<T> source,
Func<T, int> keySelector
)
{
int keyGroup = Int32.MinValue;
int currentGroupValue = Int32.MinValue;
return source
.Select(t => new {obj = t, key = keySelector(t))
.OrderBy(x => x.key)
.GroupBy(x => {
if (currentGroupValue + 1 < x.key)
{
keyGroup = x.key;
}
currentGroupValue = x.key;
return keyGroup;
}, x => x.obj);
}
You can either convert the dates to ints by means of subtraction, or imagine a DateTime version (easily).

In this case I think that a standard foreach loop is probably more readable than a LINQ query:
var relatedActivities = new List<TActivity>();
bool found = false;
foreach (var item in activities.OrderBy(a => a.ActivityDate))
{
int count = relatedActivities.Count;
if ((count > 0) && (relatedActivities[count - 1].ActivityDate.Date.AddDays(1) != item.ActivityDate.Date))
{
if (found)
break;
relatedActivities.Clear();
}
relatedActivities.Add(item);
if (item.ID == activity.ID)
found = true;
}
if (!found)
relatedActivities.Clear();
For what it's worth, here's a roughly equivalent -- and far less readable -- LINQ query:
var relatedActivities = activities
.OrderBy(x => x.ActivityDate)
.Aggregate
(
new { List = new List<TActivity>(), Found = false, ShortCircuit = false },
(a, x) =>
{
if (a.ShortCircuit)
return a;
int count = a.List.Count;
if ((count > 0) && (a.List[count - 1].ActivityDate.Date.AddDays(1) != x.ActivityDate.Date))
{
if (a.Found)
return new { a.List, a.Found, ShortCircuit = true };
a.List.Clear();
}
a.List.Add(x);
return new { a.List, Found = a.Found || (x.ID == activity.ID), a.ShortCircuit };
},
a => a.Found ? a.List : new List<TActivity>()
);

Somehow, I don't think LINQ was truly meant to be used for bidirectional-one-dimensional-depth-first-searches, but I constructed a working LINQ using Aggregate. For this example I'm going to use a List instead of an array. Also, I'm going to use Activity to refer to whatever class you are storing the data in. Replace it with whatever is appropriate for your code.
Before we even start, we need a small function to handle something. List.Add(T) returns null, but we want to be able to accumulate in a list and return the new list for this aggregate function. So all you need is a simple function like the following.
private List<T> ListWithAdd<T>(List<T> src, T obj)
{
src.Add(obj);
return src;
}
First, we get the sorted list of all activities, and then initialize the list of related activities. This initial list will contain the target activity only, to start.
List<Activity> orderedEvents = activities.OrderBy(a => a.ActivityDate).ToList();
List<Activity> relatedActivities = new List<Activity>();
relatedActivities.Add(activity);
We have to break this into two lists, the past and the future just like you currently do it.
We'll start with the past, the construction should look mostly familiar. Then we'll aggregate all of it into relatedActivities. This uses the ListWithAdd function we wrote earlier. You could condense it into one line and skip declaring previousEvents as its own variable, but I kept it separate for this example.
var previousEvents = orderedEvents.TakeWhile(a => a.ID != activity.ID).Reverse();
relatedActivities = previousEvents.Aggregate<Activity, List<Activity>>(relatedActivities, (items, prevItem) => items.OrderBy(a => a.ActivityDate).First().ActivityDate.Subtract(prevItem.ActivityDate).Days.Equals(1) ? ListWithAdd(items, prevItem) : items).ToList();
Next, we'll build the following events in a similar fashion, and likewise aggregate it.
var nextEvents = orderedEvents.SkipWhile(a => a.ID != activity.ID);
relatedActivities = nextEvents.Aggregate<Activity, List<Activity>>(relatedActivities, (items, nextItem) => nextItem.ActivityDate.Subtract(items.OrderBy(a => a.ActivityDate).Last().ActivityDate).Days.Equals(1) ? ListWithAdd(items, nextItem) : items).ToList();
You can properly sort the result afterwards, as now relatedActivities should contain all activities with no gaps. It won't immediately break when it hits the first gap, no, but I don't think you can literally break out of a LINQ. So it instead just ignores anything which it finds past a gap.
Note that this example code only operates on the actual difference in time. Your example output seems to imply that you need some other comparison factors, but this should be enough to get you started. Just add the necessary logic to the date subtraction comparison in both entries.