Develop Reference

How to remove specefic rows from linq result

I have this Linq to Entity:
var sitesGrpByClientAndFreq = from cfr in clientFullReview2
group cfr by new { cfr.inspectionFreqvency } into g
select new
{
inspectionFreqvency = g.Key.inspectionFreqvency,
siteCount = g.Select(x => x.siteId).ToArray().Distinct().Count(),
normalSitesCount = g.Where(x => x.isNormal == true).Select(x=>x.isNormal).ToArray().Count(),
}
From the above linq I get this result:
My question is How can I remove all rows where inspectionFrequency = -1?

You can mix and match the let keyword with where. It could be something like:
var sitesGrpByClientAndFreq =
from cfr in clientFullReview2
group cfr by new { cfr.inspectionFreqvency } into g
let inspectionFreqvency = g.Key.inspectionFreqvency
where inspectionFreqvency != -1
select new
{
inspectionFreqvency = inspectionFreqvency,
siteCount = g.Select(x => x.siteId).ToArray().Distinct().Count(),
normalSitesCount = g.Where(x => x.isNormal == true).Select(x=>x.isNormal).ToArray().Count(),
}

In clause in lambda expression

var Charts = chartGroup
.Descendants("charts")
.Elements("chart")
.Where(x => x.Attribute("id").Value == chartId.ToString())
.Select(x => x.Attribute("name").Value).ToList();
Here I want to use an "in-clause"" (like the in clause in SQL) for Attribute("id").Value for array of strings:
like:
Where(x => x.Attribute("id").Value in ("1","2")
Where(x => x.Attribute("id").Value` in charIds[]
how to achieve this?

If you have a set of values in an array, then you can use:
.Where(x => charids.Contains(x.Attribute("id").Value)

You can use Contains method of IEnumerable:
var ids = new[]{"1", "2"};
Where(x=>ids.Contains(x.Attribute("id").Value));
update:
moreover, this code will transfer in 'in' statement in SQL for IQueryable.

You can do something like this:
var ids = new []{"id1","id2", ... };
var Charts = chartGroup.Descendants("charts")
.Elements("chart")
.Where(x => ids.Contains(x.Attribute("id").Value))
.Select(x => x.Attribute("name").Value).ToList();

SQL Where – In Functionality can be easily achieved by Lambda Expression.
SQL query -
Select Name,Id from Category Where Id In (71,72)
Lambda Expression –
List checkedRecords = new List { 71, 72 };
var Cs = Context.Categories.Where(c => checkedRecords.Contains(c.Id));
I Hope this would help.

The IN in LINQ is Enumerable.Contains or Enumerable.Any. Here are several approaches:
string[] strIDs = new[]{ "6", "7" };
int[] intIDs = new[]{ 1, 2 };
char[] charIds = new[]{ '4', '5' };
....
.Where(x => strIDs.Contains(x.Attribute("id"))
|| intIDs.Any(i => i.ToString() == x.Attribute("id"))
|| charIds.Any(c => c.ToString() == x.Attribute("id")));

something like ... where charIds.Contains(x.Attribute"id".Value)

var memberData = (from u in _objGroupRepositoty.Value.GetUsers()
join umedia in _objGroupRepositoty.Value.GetMediaDetails() on u.userid equals umedia.userid
join gm in _objGroupRepositoty.Value.GetGroupMaster() on groupId equals gm.GDID
join m in _objGroupRepositoty.Value.GetGroupMembers() on u.userid equals m.userid
join media in _objGroupRepositoty.Value.GetMediaDetails() on gm.GDID equals media.GDID
where (m.GDID == groupId
&& m.IsActive == true
&& gm.IsActive == true
&& u.IsActive == true)
select new
{
userid = u.userid,
firstname = u.firstname,
lastname = u.lastname,
mobile_no = u.mobile_no,
imagepath = umedia.media_path,
IsAdmin = m.IsAdmin,
GroupID = gm.GroupID,
group_name = gm.group_name,
tagline = gm.tagline,
groupImage = media.media_path,
ChatRoomId = gm.ChatRoomId,
OperationType
//newMember = newMemberLists.Contains(u.userid) than "Y" : "N",
}).ToList().Distinct();

linq after groupby unable to get column values

I am getting data from multiple tables by joining and i want to group data on particular column value but after group by statement i can access my aliases and their properties. What mistake i am making?
public List<PatientHistory> GetPatientHistory(long prid)
{
using(var db = new bc_limsEntities())
{
List<PatientHistory> result =
(from r in db.dc_tresult
join t in db.dc_tp_test on r.testid equals t.TestId into x
from t in x.DefaultIfEmpty()
join a in db.dc_tp_attributes on r.attributeid equals a.AttributeId into y
from a in y.DefaultIfEmpty()
where r.prid == prid
group new {r,t,a} by new {r.testid} into g
select new PatientHistory
{
resultid = r.resultid,
bookingid = r.bookingid,
testid = r.testid,
prid = r.prid,
attributeid = r.attributeid,
result = r.result,
Test_Name = t.Test_Name,
Attribute_Name = a.Attribute_Name,
enteredon = r.enteredon,
Attribute_Type = a.Attribute_Type
}).ToList();
return result;
}
}

You're doing this wrong way. As been said by Jon after grouping the sequences with aliases r,t,a doesn't exist. After grouping you receive the sequence g with sequances of r,t,a in each element of g. If you want get one object from each group (for example most recent) you should try this:
List<PatientHistory> result =
(from r in db.dc_tresult
join t in db.dc_tp_test on r.testid equals t.TestId into x
from t in x.DefaultIfEmpty()
join a in db.dc_tp_attributes on r.attributeid equals a.AttributeId into y
from a in y.DefaultIfEmpty()
where r.prid == prid
group new {r,t,a} by new {r.testid} into g
select new PatientHistory
{
resultid = g.Select(x => x.r.resultid).Last(), // if you expect single value get it with Single()
// .... here add the rest properties
Attribute_Type = g.Select(x => x.a.Attribute_Type).Last()
}).ToList();

I appreciated this question so I thought I would add another potential usage case. I would like feedback on what the cleanest approach is to getting table information through a group operation so that I can project later in the select operation. I ended up combining what the OP did which is to pass objects into his group clause and then used the g.Select approach suggested by YD1m to get table information out later. I have a LEFT JOIN so I'm defending against nulls :
// SQL Query
//DECLARE #idCamp as Integer = 1
//
//select *,
//(select
//count(idActivityMaster)
//FROM tbActivityMasters
//WHERE dftidActivityCategory = A.idActivityCategory) as masterCount
//FROM tbactivitycategories A
//WHERE idcamp = #idCamp
//ORDER BY CategoryName
int idCamp = 1;
var desiredResult =
(from c in tbActivityCategories
.Where(w => w.idCamp == idCamp)
from m in tbActivityMasters
.Where(m => m.dftidActivityCategory == c.idActivityCategory)
.DefaultIfEmpty() // LEFT OUTER JOIN
where c.idCamp == idCamp
group new {c, m} by new { m.dftidActivityCategory } into g
select new
{
idActivityCategory = g.Select(x => x.m == null ? 0 : x.m.dftidActivityCategory).First(),
idCamp = g.Select(x => x.c.idCamp).First(),
CategoryName = g.Select(x => x.c.CategoryName).First(),
CategoryDescription = g.Select(x => x.c.CategoryDescription).First(),
masterCount = g.Count(x => x.m != null)
}).OrderBy(o=> o.idActivityCategory);
desiredResult.Dump("desiredResult");
If I just use a basic group approach I get the results but not the extra column information. At least I can't find it once I group.
var simpleGroup = (from c in tbActivityCategories
.Where(w => w.idCamp == idCamp)
.OrderBy(o => o.CategoryName)
from m in tbActivityMasters
.Where(m => m.dftidActivityCategory == c.idActivityCategory)
.DefaultIfEmpty() // LEFT OUTER JOIN
where c.idCamp == idCamp
group m by m == null ? 0 : m.dftidActivityCategory into g
select new
{
// How do I best get the extra desired column information from other tables that I had before grouping
// but still have the benefit of the grouping?
// idActivityCategory = g.Select(x => x.m == null ? 0 : x.m.dftidActivityCategory).First(),
// idCamp = g.Select(x => x.c.idCamp).First(),
// CategoryName = g.Select(x => x.c.CategoryName).First(),
// CategoryDescription = g.Select(x => x.c.CategoryDescription).First(),
// masterCount = g.Count(x => x.m != null)
idActivityCategory = g.Key,
masterCount = g.Count(x => x != null)
});
simpleGroup.Dump("simpleGroup");
Please tear this up. I'm trying to learn and it just seems like I'm missing the big picture here. Thanks.
UPDATE : Cleaned up by moving the work into the group and making the select more straight forward. If I had known this yesterday then this would have been my original answer to the OP question.
int idCamp = 1;
var desiredResult =
(from c in tbActivityCategories
.Where(w => w.idCamp == idCamp)
from m in tbActivityMasters
.Where(m => m.dftidActivityCategory == c.idActivityCategory)
.DefaultIfEmpty() // LEFT OUTER JOIN
where c.idCamp == idCamp
group new { c, m } by new
{ idActivityCategory = m == null ? 0 : m.dftidActivityCategory,
idCamp = c.idCamp,
CateGoryName = c.CategoryName,
CategoryDescription = c.CategoryDescription
} into g
select new
{
idActivityCategory = g.Key.idActivityCategory,
idCamp = g.Key.idCamp,
CategoryName = g.Key.CateGoryName,
CategoryDescription = g.Key.CategoryDescription,
masterCount = g.Count(x => x.m != null)
}).OrderBy(o => o.idActivityCategory);
desiredResult.Dump("desiredResult");

Convert from query to method

How to convert following code to method operator:
var myOrders = from c in customers
where c.Field<string>("Region") == "WA"
from o in orders
where c.Field<string>("CustomerID") == o.Field<string>("CustomerID")
&& (DateTime)o["OrderDate"] >= cutoffDate
select new {
CustomerID = c.Field<string>("CustomerID"),
OrderID = o.Field<int>("OrderID")
};
---------or----------
var myOrders = from c in customers
where c.Region == "WA"
from o in orders
where c.CustomerID == o.CustomerID
&& o.OrderDate >= cutoffDate
select new {
CustomerID = c.CustomerID,
OrderID = o.OrderID
};
same code in object form

I'd actually rewrite this as a join - probably via intermediate variables:
var washingtonCustomers = customers.Where(c => c.Field<string>("Region") == "WA");
var recentOrders = orders.Where(o => (DateTime)o["OrderDate"] >= cutoffDate);
var query = washingtonCustomers.Join(recentOrders,
c => c.Field<string>("CustomerID"),
o => o.Field<string>("CustomerID"),
(c, o) => new {
CustomerID = c.Field<string>("CustomerID"),
OrderID = o.Field<int>("OrderID")
});

You can try with this code - based on IEnumerable<KeyValuePair<string, Int32>
public IEnumerable<KeyValuePair<string, Int32>> YourQuery(DateTime date, string code)
{
var result =
from c in customers
where c.Field<string>("Region") == code
from o in orders
where c.Field<string>("CustomerID") == o.Field<string>("CustomerID")
&& (DateTime)o["OrderDate"] >= date
select new
{
CustomerID = c.Field<string>("CustomerID"),
OrderID = o.Field<int>("OrderID")
};
return result;
}

Are you just wanting to use the functional Linq syntax instead of query syntax? That would look like:
var myOrders = customers
.Where(c => c.Region == "WA")
.SelectMany(c =>
orders
.Where(o => (o.CustomerID == c.CustomerID)
&& (o.OrderDate > cutoffDate))
.Select(o => new {
CustomerID = c.CustomerID,
OrderID = o.OrderID
})
);

How to use LINQ with calculated properties in a single pass?

I'd like to make a LINQ query, extracting dynamic properties (calculated fields) of my entities in a single pass, without get the error "The specified type member 'EntityKey' is not supported in LINQ to Entities".
Here is the only working way I found, but I am sure there are better and more elegant methods:
var q = (from i in
(from x in context.Tickets
select new { x.OperatoreID, x.DataObiettivo })
group i by new { i.OperatoreID } into g
select new vmOperatoreDateObiettivo
{
OperatoreID = g.Key.OperatoreID,
NOperatore = "", // field value to be updated...
DataObiettivo = g.Max(d => d.DataObiettivo),
MinutiAllaScadenza = 0, // field to be updated...
Alert = "" // field value to be updated...
}).ToList();
// Here I update my fields with a second pass....
foreach (vmOperatoreDateObiettivo e in q)
{
string nome = context.Operatori
.Where(t => t.OperatoreID == e.OperatoreID)
.First().CognomeNomePuntato.ToString();
e.NOperatore = nome;
int minscad = context.Tickets
.Where(t => t.OperatoreID == e.OperatoreID).AsEnumerable().Min(a => a.MinutiAllaScadenza);
e.MinutiAllaScadenza = minscad;
string sev = context.Tickets
.Where(t => t.OperatoreID == e.OperatoreID).AsEnumerable().Min(a => a.Alert);
e.Alert = sev;
}
Thanks in advance!

Try adding a let clause to your query and define calculated field, like so:
var q = (from i in
(from x in context.Tickets
select new { x.OperatoreID, x.DataObiettivo })
group i by new { i.OperatoreID } into g
let nOperatore = context.Operatori
.Where(t => t.OperatoreID == e.OperatoreID)
.First().CognomeNomePuntato.ToString() &&
minutialla = context.Tickets
.Where(t => t.OperatoreID == e.OperatoreID)
.AsEnumerable().Min(a => a.MinutiAllaScadenza) &&
alert = context.Tickets
.Where(t => t.OperatoreID == e.OperatoreID)
.AsEnumerable().Min(a => a.Alert)
select new vmOperatoreDateObiettivo
{
OperatoreID = g.Key.OperatoreID,
NOperatore = nOperatore,
DataObiettivo = g.Max(d => d.DataObiettivo),
MinutiAllaScadenza = minutialla,
Alert = alert
}).ToList();