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How to add serial no in IQueryable query in LinQ?

This is my method that returns IQueryable query. I want to generate serial no based on number of records.
public IQueryable<CompanyModel> GetCompanyData()
{
var query = (from e in Context.tblCompany
where e.Cmp_Id == this.CompanyId
&& e.TenantId == this.TenantId
select new CompanyModel()
{
CmpId = e.Cmp_Id,
SrNo = 0,
});
return query;
}

You can try below code may it help you
public IQueryable<CompanyModel> GetCompanyData()
{
List<CompanyModel> query = (from e in Context.tblCompany
where e.Cmp_Id == this.CompanyId
&& e.TenantId == this.TenantId
select new CompanyModel()
{
CmpId = e.Cmp_Id,
SrNo = 0,
}).ToList();
int counter=0;
query.Foreach(x=>x.SrNo = counter++);
return query;
}

As far as I am aware, the only way to have sequence number generated by the query itself is using "Select" method overload with 2 parameters, however it doesn't work with IQueryable, so your query will look like:
Context.tblCompany.Where(e => e.Cmp_Id == this.CompanyId && e.TenantId == this.TenantId)
.Select(e => new { CmpId = e.Cmp_Id })
.AsEnumerable()
.Select((e, i) => new CompanyModel { CmpId = e.CmpId, SrNo = i });
Obviously, this sequence number will be generated on the client and the resulting expression can't be treated as IQueryable anymore. At the same time, the part before "AsEnumerable" will be successfully translated into SQL.

Expression tree for groupby with where clause and than select

From UI dynamic column are coming as parameter in API and based on the parameter I have to fetch data from database.
Example : In the below code, based on the column if condition linq query is being executed. Now I want to make it generic so that it serve if new column condition come in future.
public List<string> GetFilteredTypeAhead(string searchText,string searchForRole,int fiscalyear,int fiscalPeriod)
{
if (searchForRole == "column1")
{
var accounts = (from a in _context.Account
where a.column1.StartsWith(searchText) && a.FiscalPeriod == fiscalPeriod && a.FiscalYear ==fiscalyear
group a.column1 by a.column2 into g
select g.Key).ToList();
return accounts;
}
else if(searchForRole == "column2")
{
var accounts = (from a in _context.Account
where a.column2.StartsWith(searchText) && a.FiscalPeriod == fiscalPeriod && a.FiscalYear == fiscalyear
group a.column2 by a.column2 into g
select g.Key).ToList();
return accounts;
}
else if (searchForRole == "column3")
{
var accounts = (from a in _context.Account
where a.column3.StartsWith(searchText) && a.FiscalPeriod == fiscalPeriod && a.FiscalYear == fiscalyear
group a.column3 by a.column3 into g
select g.Key).ToList();
return accounts;
}
else if (searchForRole == "column4")
{
var accounts = (from a in _context.Account
where a.column4.StartsWith(searchText) && a.FiscalPeriod.Equals(fiscalPeriod) && a.FiscalYear.Equals(fiscalyear)
group a.column4 by a.column4 into g
select g.Key).ToList();
return accounts;
}
else
{
return new List<string>();
}
}
To convert it to generic. I created a expression tree.
static IQueryable<T> ConvertToExpression<T>(IQueryable<T> query, string propertyValue, PropertyInfo propertyInfo, int fiscalyear, int fiscalPeriod)
{
ParameterExpression e = Expression.Parameter(typeof(T), "e");
MemberExpression m = Expression.MakeMemberAccess(e, propertyInfo);
ConstantExpression c = Expression.Constant(propertyValue, typeof(string));
MethodInfo mi = typeof(string).GetMethod("StartsWith", new Type[] { typeof(string) });
Expression call = Expression.Call(m, mi, c);
PropertyInfo propertyInfoFiscalPeriod = typeof(T).GetProperty("FiscalPeriod");
MemberExpression memberPropertyFiscalPeriod = Expression.Property(e, propertyInfoFiscalPeriod);
ConstantExpression right = Expression.Constant(fiscalPeriod);
Expression equalsFiscalPeriod = Expression.Equal(memberPropertyFiscalPeriod, Expression.Convert(right, typeof(Int16)));
PropertyInfo propertyInfoFiscalYear = typeof(T).GetProperty("FiscalYear");
MemberExpression memberPropertyFiscalYear = Expression.Property(e, propertyInfoFiscalYear);
right = Expression.Constant(fiscalyear);
Expression equalsFiscalYear = Expression.Equal(memberPropertyFiscalYear, Expression.Convert(right, typeof(Int16)));
Expression combineExpression = Expression.And(equalsFiscalPeriod, equalsFiscalYear);
Expression predicateBody = Expression.And(call, combineExpression);
Expression<Func<T, bool>> lambda = Expression.Lambda<Func<T, bool>>(predicateBody, e);
return query.Where(lambda);
}
And To call it I used code like below
"searchForRole" comes as parameter in as "column1","column2" etc
PropertyInfo propertyInfo = typeof(Account).GetProperty(searchForRole);
IQueryable<Account> query = _context.Account;
query = ConvertToExpression(query, searchText, propertyInfo,fiscalyear,fiscalPeriod);
var list = query.ToList();
Now this is working fine but the result having duplicate records. I wanted to have some distinct or group by on passed parameter column. In Simple words I wanted to remove if condition and make my search method generic. Please help.

It's possible, but IMHO it's better to keep the dynamic parts at minimum and use the C# compile time safety as much as possible.
The sample query in question
var accounts = (from a in _context.Account
where a.column1.StartsWith(searchText) && a.FiscalPeriod == fiscalPeriod && a.FiscalYear ==fiscalyear
group a.column1 by a.column1 into g
select g.Key).ToList();
can be rewritten as follows
var accounts = _context.Account
.Where(a => a.FiscalPeriod == fiscalPeriod && a.FiscalYear == fiscalyear)
.Select(a => a.column1)
.Where(c => c.StartsWith(searchText))
.Distinct()
.ToList();
As you can see, the only dynamic part is a => a.column1 of type Expression<Func<Account, string>>. So all you need is a method like this:
static Expression<Func<T, M>> MemberSelector<T>(string name)
{
var parameter = Expression.Parameter(typeof(T), "e");
var body = Expression.PropertyOrField(name);
return Expression.Lambda<Func<T, M>>(body, parameter);
}
and to replace
.Select(a => a.column1)
with
.Select(MemberSelector<Account, string>(searchForRole))

EntityFramework LINQ query count fails but query returns result. How to optimize LINQ query?

I have the below LINQ query that performs a self-left-outer-join. The querys looks a little complex but is simply doing a self join on itself(purpose if to join each record with the record for it previous business day) and then doing some parameterized filtering.
var newBreakThreshold = decimal.Parse(WebConfigurationManager.AppSettings["NewBreakThreshold"]);
using (var dbContext = new NavFoToBoCompareDbContext())
{
var query = from current in dbContext.NAVSummaries
let currentWD = SqlFunctions.DatePart("dw", current.ValueDate)
let currentPD = DbFunctions.AddDays(current.ValueDate, currentWD == 2 ? -3 : currentWD == 1 ? -2 : -1).Value
join previous in dbContext.NAVSummaries
on new { current.Portfolio, PD = currentPD }
equals new { previous.Portfolio, PD = previous.ValueDate }
into previousGroup
from previous in previousGroup.DefaultIfEmpty() // LEFT OUTER JOIN
select new { outer = current, inner = previous };
if (dateStart.HasValue)
query = query.Where(e => e.outer.ValueDate >= dateStart.Value);
if (dateEnd.HasValue)
query = query.Where(e => e.outer.ValueDate <= dateEnd.Value);
if (!portfolio.Equals("ALL", StringComparison.OrdinalIgnoreCase))
query = query.Where(e => e.outer.Portfolio.Equals(portfolio, StringComparison.OrdinalIgnoreCase));
if (!owner.Equals("ALL", StringComparison.OrdinalIgnoreCase))
query = query.Where(e => e.outer.PortfolioOwner.Equals(owner, StringComparison.OrdinalIgnoreCase));
if (status != 0)
query = query.Where(e => e.outer.Statuses.Any(s => s.StatusId == status));
var query2 = query.Select(s => new
{
BackOfficeNAV = s.outer.BackOfficeNAV,
FrontOfficeNAV = s.outer.FrontOfficeNAV,
Threshold = s.outer.Threshold,
ExtractId = s.outer.ExtractId,
ExtractStatus = s.outer.ExtractStatus,
PortfolioOwner = s.outer.PortfolioOwner,
DateTimeModified = s.outer.DateTimeModified,
MostCorrectNAV = s.outer.MostCorrectNAV,
Comments = s.outer.Comments,
Statuses = s.outer.Statuses,
Extracts = s.outer.Extracts,
Portfolio = s.outer.Portfolio,
ValueDate = s.outer.ValueDate,
DifferencePercent = s.outer.DifferencePercent,
DayOverDayChange = s.outer.DifferencePercent - s.inner.DifferencePercent,
IsChange = s.inner.DifferencePercent != s.outer.DifferencePercent,
PreviousValueDate = s.inner.ValueDate,
PreviousDifferencePercent = s.inner.DifferencePercent
});
query2 = query2.Where(r => "NEW".Equals(breakOption, StringComparison.OrdinalIgnoreCase) ?
((r.DifferencePercent > r.Threshold) && r.IsChange && r.DayOverDayChange > newBreakThreshold) :
"OLD".Equals(breakOption, StringComparison.OrdinalIgnoreCase) ? (r.DifferencePercent > r.Threshold) :
"ALL".Equals(breakOption, StringComparison.OrdinalIgnoreCase));
var resultCount = query2.Count();
}
The query is used in two places. In one method it used for computing the count required for pagination. In another method it is used for getting the actual results from the database. The implementation for getting the actual results for a bigger result set executes successfully, whereas the the Count() query fails with a Timeout exception. Note:Both implementations are exactly the same.
Can someone help me in optimizing this query as well. Thanks in advance.

Not quite sure that's the problem, but at least let try to eliminate the potential effect of the so called Parameter Sniffing Problem by eliminating the dateStart / dateEnd parameters by manually building expression with constant values.
First, a little helper method:
using System;
using System.Linq;
using System.Linq.Expressions;
public static class QueryableUtils
{
public static IQueryable<T> WhereBetween<T>(this IQueryable<T> source, Expression<Func<T, DateTime>> dateSelector, DateTime? startDate, DateTime? endDate)
{
if (startDate == null && endDate == null) return source;
var startCond = startDate != null ? Expression.GreaterThanOrEqual(dateSelector.Body, Expression.Constant(startDate.Value)) : null;
var endCond = endDate != null ? Expression.LessThanOrEqual(dateSelector.Body, Expression.Constant(endDate.Value)) : null;
var predicate = Expression.Lambda<Func<T, bool>>(
startCond == null ? endCond : endCond == null ? startCond : Expression.AndAlso(startCond, endCond),
dateSelector.Parameters[0]);
return source.Where(predicate);
}
}
Then try the following and see if it helps:
//if (dateStart.HasValue)
// query = query.Where(e => e.outer.ValueDate >= dateStart.Value);
//if (dateEnd.HasValue)
// query = query.Where(e => e.outer.ValueDate <= dateEnd.Value);
query = query.WhereBetween(e => e.outer.ValueDate, dateStart, dateEnd);

You can simply use AsParallel() to enable multithreading execution of the linq query.
You should then check your tables' indexes to improve performances.

Comma separated List in linq select

I have Table HR_Travel(TravelID, TravelCode....) and HR_TravelDocuments(TravelDocID, TravelID, DocUrl)
FromDate = FromDate.AddDays(1);
ToDate = ToDate.AddDays(1);
List<dynamic> Lst = new List<dynamic>();
var queryTravelDetails = from t in db.HR_TravelDetails
where ((t.StatusDate >= FromDate && t.StatusDate <= ToDate)
&& (t.EmpID == EmpID || EmpID == 0) && (t.TravelStatus == TravelStatus || TravelStatus == "All"))
orderby t.StatusDate descending
select new
{
TravelID = t.TravelID,
TravelSubID = db.HR_TravelDetails.Where(i => i.TravelID == 0).FirstOrDefault().TravelID == null ? 0 : db.HR_TravelDetails.Where(i => i.TravelID == 0).FirstOrDefault().TravelID,
t.TravelCode,
t.EmpID,
EmpName = db.EE_Employee.Where(i => i.EmpID == t.EmpID).FirstOrDefault().EmpName,
t.CellNo,
t.BoardingForm,
t.DestinationTO,
t.JournyDate,
t.Purpose,
t.Organization,
t.TravelStatus,
DocUrl = DocUrl = string.Join(",",( db.HR_TravelDocuments.Where(i => i.TravelID == t.TravelID && i.TravelSubID == 0).Select(i => i.DocUrl).ToList()))
};
foreach (var element in queryTravelDetails)
{
Lst.Add(element);
}
Gives the following error:
LINQ to Entities does not recognize the method 'System.String Join[String](System.String, System.Collections.Generic.IEnumerable`1[System.String])' method, and this method cannot be translated into a store expression.

The Join() method can't be used in LINQ expressions, because it cannot translate from CLR to T-SQL. Another example is that you can't use:
var itemCount = db.Table.Count(p => p.Something == SomeFunction(someVariable));
You should move the method call outside the LINQ statement:
var anotherVariable = SomeFunction(someVariable);
var itemCount = db.Table.Count(p => p.Something == anotherVariable);
I hope I explained in a good way.
EDIT: As seen in the comments before, you can also use ToArray() and when the data is loaded locally you can use functions in statements freely.

how to create dynamic linq query based on search criterias

I have a search form which i want to use to search a database for data. The searchbox has 4 checkboxes and 1 textfield. The problem is how do i build the linq query considering i dont know beforehand what textboxes the user will check for filtering the search. What i have so far is:
[HttpPost]
public ActionResult search(string ulv, string bjorn, string jerv, string gaupe)
{
var query = (from o in db.observasjonene select o);
if (ulv != null)
{
query = query.Where(o => o.art == ulv);
}
if (bjorn != null)
{
query = query.Where(o => o.art == bjorn);
}
if (jerv != null)
{
query = query.Where(o => o.art == jerv);
}
if (gaupe != null)
{
query = query.Where(o => o.art == gaupe);
}
IEnumerable ls = query.ToList();
return Json(ls, JsonRequestBehavior.AllowGet);
}
The problem with the "where" clause is that if a condition is true, it overwrites the results from the earlier condition. I guess i need an "or" statement or something..

If I have understood your question correctly, you want to check if art equals to any of provided values. You can combine those values into collection and check if collection contains art value:
var values = new [] { ulv, bjorn, jerv, game }.Where(v => v != null);
var query = from o in db.observasjonene
where values.Contains(o.art)
select o;
EF translates Contains into SQL IN operator.

I'm using two approaches in this case:
Build dynamic query:
var q = DB.Invoices.AsQueryable();
if (isPresented != null)
q = q.Where(iv => iv.IsPresented == isPresented);
if (ID != null)
q = q.Where(iv => iv.ID == ID.Value);
...........................
return from iv in q
orderby iv.DueDate descending
select iv;
Use Union to combine search results:
var q1 = db.FeeInvoice.Where(fi => [QUERY1]));
if (isPresented != null)
{
var q2 = db.FeeInvoice.Where(fi =>[QUERY2]));
q1.Union(q2);
}
if (ID != null)
{
var q3 = db.FeeInvoice.Where(fi =>[QUERY3]);
q1.Union(q3);
}
...........................

You are comparing all the parameters value to single column in the query ie. art (see you have written same column name in each where condition) . I'm not sure why are you doing so? you can simply take single parameter which compare the value like this
public ActionResult search(string value)
{
query = query.Where(o => o.art == value);
}
or if it is by mistake and you want to apply where condition along with multiple column then you can try something like this
query=query.Where(o => (o.art == ulv || ulv == string.Empty) && (o => o.bjorn == bjorn || bjorn=string.empty) && (o.jerv == jerv || jerv == string.Empty) && (o.gaupe == gaupe || gaupe == string.Empty));
Note: I assume your column name as your parameters name.