Develop Reference

Linq where clause confusion

Good day, everyone!
I've written one query for my Automation test, but it's taking too long to execute, and I'm not sure how to optimize it effectively because I'm new to the Linq where clause.
Could someone please assist me with this?
var order = OrderRepositoryX.GetOrderByStatus(OrderStatusType.Dispatched, 4000)
.Where(x => x.siteId == 1 || x.siteId == 10 || x.siteId == 8 || x.siteId == 16 || x.siteId == 26 || x.siteId == 27)
.Where(x =>
{
var totalPrice = OrderRepository.GetOrderById(shared_parameters.testConfiguration, x.orderId).TotalPrice;
if (totalPrice < 500)
return false;
return true;
})
.Where(x =>
{
var cnt = ReturnOrderRepositoryX.CheckReturnOrderExists(x.orderId);
if (cnt > 0)
return false;
return true;
})
.Where(x =>
{
var cnt = OrderRepositoryX.CheckActiveOrderJobDetailsByOrderId(x.orderId);
if (cnt > 0)
return false;
return true;
})
.FirstOrDefault();

The biggest code smell here is that you are calling other repositories inside the Where clause which (assuming that repositories actually hit database) it will effectively mean that you are hitting database per every queried item. Lets imagine that OrderRepositoryX.GetOrderByStatus(OrderStatusType.Dispatched, 4000) and first Where will result in 1000 items, only second Whereclause will lead to 1000 queries to the database (and you have some more calls to repositories in subsequent Wheres). And all of this to get just one item (i.e. FirstOrDefault).
Usual approach is to avoid calling database in loops (what Where basically does here) and rewrite such code so only single SQL query will be performed against the database returning only what is needed and performing all the filtering on the database side.

Please try this instead
Avoid too many where clauses. It gets a result and then applies another check on the whole set.
var order = OrderRepositoryX.GetOrderByStatus(OrderStatusType.Dispatched, 4000)
.FirstOrDefault(x => x.siteId == 1 || x.siteId == 10 || x.siteId == 8 || x.siteId == 16 ||
x.siteId == 26 || x.siteId == 27) &&
(x =>
{
var totalPrice = OrderRepository.GetOrderById(shared_parameters.testConfiguration, x.orderId)
.TotalPrice;
return totalPrice >= 500;
})
&& (x =>
{
var cnt = ReturnOrderRepositoryX.CheckReturnOrderExists(x.orderId);
return cnt <= 0;
})
&& (x =>
{
var cnt = OrderRepositoryX.CheckActiveOrderJobDetailsByOrderId(x.orderId);
return cnt <= 0;
});

How to write a linq query to exclude some of the records?

This is my LINQ
IList<string> ExceptList = new List<string>() { "045C388E96", "C9B735E166", "02860EB192", "2401016471" };
var listusers = context.USER_INFO.Where(x => x.ACTIVATED
&& x.COMP.EQUIPMENT.Count(y => y.STATUS == (int)STATUSEQ.ACTIVE) > 0
&& (x.LAST_LOGIN < time)
&& !ExceptList.Contains(x.COMP.CODE)
&& !x.IS_LOCK
|| !x.COMP.IS_LOCK)
.Select(x => new EmailOutOfDateLoginModel
{
COMPCode = x.COMP.CODE,
First_Name = x.FIRST_NAME,
Last_Name = x.LAST_NAME,
Total_EQ = x.COMP.EQUIPMENT.Count(y => y.STATUS == (int)STATUSEQ.ACTIVE),
User_Email = x.USER_EMAIL
}).ToList();
I am not sure why my ExceptList is not working. I want to exclude any record that contaisn any of the CODE in the ExceptList

Put parentheses around the expressions containing the && logic. The || at the end is only matched with the !x.IS_LOCK || !x.COMP.IS_LOCK otherwise.

According your linq all records where (!x.COMP.IS_LOCK==true) will be included in the query. Try this "where" part:
.Where(x => x.ACTIVATED
&& x.COMP.EQUIPMENT.Count(y => y.STATUS == (int)STATUSEQ.ACTIVE) > 0
&& (x.LAST_LOGIN < time)
&& !ExceptList.Contains(x.COMP.CODE)
&& !(x.IS_LOCK && x.COMP.IS_LOCK))

LINQ Query with method syntax

My requirement is to make boolean value (IsPC=true) only if I found any value with IsCurrent = true from the list and second condition is to filter the list with G or W codes and third condition is to check the PCBNumber length ==15 with only one from the list.
How short can i able to reduce the below query using LINQ method syntax
below is my query
var CurrentQ= p.List.Where(x => x.IsConCurrent== true);
if (CurrentQ.Count() > 0)
{
var NCurrentQwithWorQ = p.List.Where(x => x.Codes == Codes.W|| x.Codes== Codes.Q).Count();
if (NCurrentQwithWorQ != null)
{
var PCBNumber = p.List.Where(x => x.PCBNumber .Length == 15).Count();
if (PCBNumber == 1)
{
isPC = true;
}
}
}

You can use all conditions in same query like below,
var PCBNumber= p.List.Where(x => x.IsConCurrent== true && (x.Codes == Codes.W|| x.Codes== Codes.Q) && x.PCBNumber.Length == 15);
if (PCBNumber !=null && PCBNumber.Count() == 1)
{
isPC = true;
}

I'm not trying to debug what you wrote, but isn't this really what you're looking for--that is, daisy-chaining your Where conditions?
var isPC = p.List.Where(x => x.IsConCurrent == true).Where(x => x.Codes == Codes.W || x.Codes == Codes.Q).Where(x => x.PCBNumber.Length == 15).Count() == 1;

Both solutions suggested above are correct.
p.List.Where(x => x.IsConCurrent== true && (x.Codes == Codes.W|| x.Codes== Codes.Q) && x.PCBNumber.Length == 15);
p.List.Where(x => x.IsConCurrent == true).Where(x => x.Codes == Codes.W || x.Codes == Codes.Q).Where(x => x.PCBNumber.Length == 15).Count()
Actually they are performed in the same way. The Where function does not force immediate iteration through the data source. Only when you execute the Count function, LINQ will process row by row and execute criterion by criterion to find out which values should be calculated.
I can only suggest you add the Take(2) operator after the where clause. In this case LINQ will stop after finding the first two rows that matches provided criterion and other rows will not be processed.
p.List.Where(x => x.IsConCurrent == true)
.Where(x => x.Codes == Codes.W || x.Codes == Codes.Q)
.Where(x => x.PCBNumber.Length == 15)
.Take(2).Count()

Optimizing a very large LINQ query

I need to write a/multiple LINQ queries to get some data that I will display for a report.
The tables I need to use are StaffingResources, StaffingForecastEvents (which link a StaffingResource to a Project), and StaffingForecasts (which link to StaffingForecastEvents and contain hours for each week). Each StaffingResource can have 0-many StaffingForecastEvents, and a StaffingForecastEvent can have 0-many StaffingForecasts.
I need to write LINQ query that, for each Resource, will contain all of the projects they have ForecastEvents on, and for each Project all of their Forecasts for a given date range (which is either a 12 weeks or 6 months). Here is what I have so far, and it is running pretty slow.
// Get date ranges
var dates = new List<DateTime>();
var startDate = range == (int)RangeTypes.WEEKLY
? DateTime.Today.AddDays(DayOfWeek.Monday - DateTime.Today.DayOfWeek)
: new DateTime(DateTime.Today.Year, DateTime.Today.Month, 1);
for (var i = 0; i < (range == (int)RangeTypes.WEEKLY ? 4 : 6); i++)
{
dates.Add(range == (int)RangeTypes.WEEKLY ? startDate.AddDays(i * 7) : startDate.AddMonths(i));
}
var endDate = dates[dates.Count-1];
// Get resources
var resources = from r in context.StaffingResourceDatas
where r.EmployeeId.HasValue
&& (resourceIds.Count == 0 || resourceIds.Contains(r.EmployeeId.Value))
&& (resourceDivisions.Count == 0 || resourceDivisions.Contains(r.ResourceDivisionId))
&& (resourceTitles.Count == 0 || resourceTitles.Contains(r.ResourceTitleId))
&& (resourceLocations.Count == 0 || resourceLocations.Contains(r.ResourceLocationId))
&& (supervisors.Count == 0 || supervisors.Contains(r.ReportsToId))
&& (showAllResources || (!showAllResources && !exclusionList.Contains(r.ResourceTitleId)))
join fe in context.StaffingForecastEvents
.Include(x => x.StaffingForecasts)
.Include(x => x.StaffingUser)
.Include(x => x.StaffingUser1)
.Include(x => x.StaffingForecasts.Select(y => y.StaffingUser))
.Include(x => x.StaffingForecasts.Select(y => y.StaffingUser1))
on r.ResourceId equals fe.ResourceId into g1
from fe in g1.DefaultIfEmpty()
join p in context.StaffingProjectDatas on fe.JobNumber equals p.JobNumber into g2
from p in g2.DefaultIfEmpty()
group new { ForecastEvent = fe, Project = p } by r into g3
select new
{
ResourceId = g3.Key.ResourceId,
Name = g3.Key.ResourceName,
Title = g3.Key.ResourceTitle,
Division = g3.Key.ResourceDivision,
Location = g3.Key.ResourceLocation,
AvailableDate = g3.Key.AvailableDate,
SupervisorEmail = g3.Key.ManagerEmail,
Projects = g3.Where(p => p.ForecastEvent != null).Select(p => new
{
JobNumber = p.ForecastEvent.JobNumber,
Description = p.Project.ProjectDescription,
Name = p.Project.ProjectName,
Division = p.Project.ProjectDivision,
ProjectManager = p.Project.PMName,
Notes = p.ForecastEvent.Notes,
LogDate = p.ForecastEvent.LogDate,
LogUser = p.ForecastEvent.StaffingUser.Name,
AckDate = p.ForecastEvent.AcknowledgeDate,
AckUser = p.ForecastEvent.StaffingUser1 != null ? p.ForecastEvent.StaffingUser1.Name : null,
Usages = dates.Select(d => new
{
Date = d,
Hours = (range == (int)RangeTypes.WEEKLY)
? (p.ForecastEvent.StaffingForecasts.Where(f => f.Date == d).Any() ? p.ForecastEvent.StaffingForecasts.Where(f => f.Date == d).Sum(f => f.Hours) : 0)
: (p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).Any() ? p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).Sum(f => f.Hours) : 0),
LogDate = (range == (int)RangeTypes.WEEKLY)
// Get acknowledge or log date for week
? (p.ForecastEvent.StaffingForecasts.Where(f => f.Date == d).Any()
? ((p.ForecastEvent.StaffingForecasts.FirstOrDefault(f => f.Date == d).AcknowledgeDate) != null)
? (p.ForecastEvent.StaffingForecasts.FirstOrDefault(f => f.Date == d).AcknowledgeDate)
: (p.ForecastEvent.StaffingForecasts.FirstOrDefault(f => f.Date == d).LogDate)
: null)
// Get acknowledge or log date for most recent forecast for month
: (p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).Any()
? ((p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).OrderByDescending(f => f.LogDate).FirstOrDefault().AcknowledgeDate) != null)
? (p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).OrderByDescending(f => f.LogDate).FirstOrDefault().AcknowledgeDate)
: (p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).Max(f => f.LogDate))
: null),
LogUser = (range == (int)RangeTypes.WEEKLY)
// Get acknowledge or log user for week
? (p.ForecastEvent.StaffingForecasts.Where(f => f.Date == d).Any()
? ((p.ForecastEvent.StaffingForecasts.FirstOrDefault(f => f.Date == d).AcknowledgeDate) != null)
? (p.ForecastEvent.StaffingForecasts.FirstOrDefault(f => f.Date == d).StaffingUser1.Name)
: (p.ForecastEvent.StaffingForecasts.FirstOrDefault(f => f.Date == d).StaffingUser.Name)
: null)
// Get acknowledge or log user for most recent forecast for month
: (p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).Any()
? ((p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).OrderByDescending(f => f.LogDate).FirstOrDefault().AcknowledgeDate) != null)
? (p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).OrderByDescending(f => f.LogDate).FirstOrDefault().StaffingUser1.Name)
: (p.ForecastEvent.StaffingForecasts.Where(f => f.Date.Year == d.Year && f.Date.Month == d.Month).OrderByDescending(f => f.LogDate).FirstOrDefault().StaffingUser.Name)
: null),
})
})
};
I will also need to get totals for each resource for each date range.
I feel like the bottleneck is probably with all the "Where"s when looping through the dates, but I don't know what else to do. Any ideas?

As a starting point you can split it up into several expressions using IQueryable<T>. It would also help you make your where clauses simpler. That would look something like:
var queryable = context.StaffingResourceDatas.Where(r => r.EmployeeId.HasValue);
if(resourceIds.Any())
{
queryable = queryable.Where(r => resourceIds.Contains(r.EmployeeId.Value))
}
Notice that this will generate SQL related to filtering by resourceIds only if resourceIds is not empty, thus potentially saving the overhead of checking it in the generated query itself.
You can write the rest of the filters similarly to this one. Also notice that query won't get executed until you call ToList() on it. So you can keep adding as many clauses as you like, until you're done constructing it.
But at the end of the day you might want to consider writing this one in raw SQL because it's just, you know, gigantic.

Linq - Dynamic Condition

I have the following query :-
I want to add one more condition which is dynamic, so if user passes DATEOFBIRTH it should be e.DateOfBirth <= date.
var data = ctx.Employee.Where(e => e.Id == Id
&& e.Category == Category
&& e.DateOfJoining <= date)
.Select(e => e)
.ToList();
How to condition dynamically?

You can use reflection to solve this problem but there is another idea that may helps you:
var criteria = new Dictionary<string, Func<Employee, bool>>();
var date = DateTime.Now; //or any other value
//Initialize your criterias
criteria.Add("DATEOFBIRTH", e => e.DateOfBirth <= date);
criteria.Add("DateOfJoining", e => e.DateOfJoining <= date);
var selectedValue = "DATEOFBIRTH";
var data = ctx.Employee.Where(e => e.Id == id &&
e.Category == Category &&
criteria[selectedValue](e)).ToList();
So if you change the selectedValue the output will be based on corresponding criteria you are looking for.

From your comment:
If the DateOfBirth is choosen, there where condition should be appended
by one more condition e.DateOfBirth <= date.. if user chooses
DateOfAnniversary then it should be e.DateOfAnniversary <= date
Then you could use:
var data = ctx.Employee
.Where(e => e.Id == Id && e.Category == Category && e.DateOfJoining <= date);
Now, assuming that filterbyDateOfBirth and filterbyDateOfAnniversary are bools:
if(filterbyDateOfBirth)
data = data.Where(e => e.DateOfBirth <= date);
if(filterbyDateOfAnniversary)
data = data.Where(e => e.DateOfAnniversary <= date);
var list = data.ToList();
Due to LINQ's deferred execution the database is queried just once at ToList.

Sounds like you're trying to do the following:
var employees = ctx.Employee.Where(e => e.Id == Id
&& e.Category == Category
&& e.DateOfJoining <= date);
if (!string.IsNullOrWhiteSpace(DATEOFBIRTH))
{
employees = employees.Where(e => e.DateOfBirth <= DATEOFBIRTH);
}
var data = employees.ToList();
You could also do the following, which is more concise, but since it looks like you are querying a database here, I would prefer the above approach since it doesn't include anything unnecessary in the query.
var data = ctx.Employee.Where(e => e.Id == Id &&
e.Category == Category &&
e.DateOfJoining <= date &&
(string.IsNullOrWhiteSpace(DATEOFBIRTH) ||
e.DateOfBirth <= DATEOFBIRTH))
.ToList();