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LINQ Conditional OrderBy

I'm trying to do a conditional OrderBy but it's having no effect. The List outputs the same with default ordering.
I've tried both approaches suggested in this question Conditional "orderby" sort order in LINQ
var query = _context.Groups
.Where(gr => gr.Status != ((sbyte)ActiveStatus.DELETED)
&& gr.OrganisationId == user.OrganisationId
&& (search != null && gr.Name != null ? (gr.Name.Contains(search)) : true == true)
)
.Select(GroupReportModel.Projection);
if(!pager.Sort.HasValue || pager.Sort.Value == ((int)Sort.MODIFIED))
query.OrderByDescending(gr => gr.Created.Date);
if(pager.Sort.Value == ((int)Sort.NAME))
query.OrderByDescending(gr => gr.Name);
pager.TotalRecords = query.Count();
var list = query.Skip(pager.PageCount != null ? pager.PageCount.Value * (pager.Page.Value) : 0)
.Take(pager.PageCount != null ? pager.PageCount.Value : 0)
.ToList();

LINQ methods do not mutate the query object, they return a new one, you need to reassign it:
if(!pager.Sort.HasValue || pager.Sort.Value == ((int)Sort.MODIFIED))
query = query.OrderByDescending(gr => gr.Created.Date);
if(pager.Sort.Value == ((int)Sort.NAME))
query = query.OrderByDescending(gr => gr.Name);
....

How to use a conditional or in linq and C#

In the following GetByExpression, sometimes the r.branchid is null. How do I add a conditional in there so it utilises a different field (r.Invoice.Branch.Id) to check against when r.branchid is null?
var t = receiptRepo
.GetByExpression(r => r.BranchId == branchId)
.Where(r => r.Date == selectedDate && r.BatchId == null)
.ToList();

Use a ternary operation
(r.BranchId != null? r.BranchId:r.Invoice.Branch.Id ) == branchId //or whatever you want to compare

You can try using null-coalescing operator ??:
r => (r.BranchId ?? r.Invoice.BranchId) == branchId
Here if r.BranchId is null we use r.Invoice.BranchId to compare with branchId. Note, that we can chain ?? operators, e.g.
r => (r.BranchId ?? r.Invoice.BranchId ?? r.Bill.BranchId) == branchId
we try BranchId if it's null, we have a look at r.Invoice.BranchId and if it's null we get r.Bill.BranchId etc.
Your Linq query can be
var t = receiptRepo
.GetByExpression(r => (r.BranchId ?? r.Invoice.BranchId) == branchId)
.Where(r => r.Date == selectedDate && r.BatchId == null)
.ToList();

You can do this:
var t = receiptRepo
.GetByExpression(r => (r?.BranchId ?? r.Invoice.BranchId) == branchId)
.Where(r => r.Date == selectedDate && r.BatchId == null)
.ToList();

What is the best way to search data on multiple fields [duplicate]

This question already has answers here:
Dynamic where clause (OR) in Linq to Entities
(2 answers)
Closed 5 years ago.
I am working in ASP.NET MVC, I have a scenario where user can select multiple options to get list of doctors, this is how my action looks like.
public JsonResult DoctorsList(int? specialization , int? city, int? area, int? insurance_company, string doctor_name )
Any of these arguments can have some value and any number of them can be null also all of can be null in that I will return all the records.
Now I know a long and complicated way where I can make different combinations of these arguments and check which one is null and which one is not and then write my query based on that.
But is there any other shorter more efficient way?
Right now I am using OR conditions to get records like this
var doctors = db.Doctors.Where(e =>
e.specialization == specialization ||
e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).Area.city_id == city ||
e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).area_id == area ||
e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).ClinicInsuranceCompanies
.Select(sin=>sin.company_id).ToList().Contains(insurance_company) ||
e.first_name == doctor_name ||
e.last_name == doctor_name
)
.Select(s => new
{
doctor_name = s.first_name + " " + s.last_name
}).ToList();
But I want it to work in combinations, For Example Selecting Doctors with specialization_id = 1 and city_id=2 , of other combinations like this. But OR condition will be true if only one condition matches

For your scenario i think this approach might work rather than going around if else conditions. And i think && should be used to filter out exactly but you could use || operator if thats what you want,
var doctors = db.Doctors.Where(e =>
(specialization != null && e.specialization == specialization) &&
(city != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).Area.city_id == city) &&
(area != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).area_id == area) &&
(insurance_company != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).ClinicInsuranceCompanies
.Select(sin => sin.company_id).ToList().Contains(insurance_company)) &&
(doctor_name != "" && e.first_name == doctor_name || e.last_name == doctor_name)
)
.Select(s => new
{
doctor_name = s.first_name + " " + s.last_name
}).ToList();

This is what I was looking for #imanshu15 answer gave me a hint.
var doctors = db.Doctors.Where(e =>
(specialization != null && e.specialization == specialization) || (specialization == null)
).Where(e =>
(city != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).Area.city_id == city) || (city == null)
).Where(e =>
(area != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).area_id == area) || (area == null)
).Where(e =>
(insurance_company != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).ClinicInsuranceCompanies
.Select(sin => sin.company_id).ToList().Contains(insurance_company)) || (insurance_company == null)
).Where(e =>
(doctor_name != null && e.first_name == doctor_name) || (doctor_name == null)
)

How can I write the following lambda expression in one line?

I want to fetch the records as follows
SearchResult.condition is null then fetch all the rows from Person
if SearchResult.condition is false then fetch the rows where PersonType column contains null value
if SearchResult.condition is true then fetch the rows where PersonType column contains non null value
struct SearchResult
{
public string Name;
public bool? condition;
}
Expression<Func<Person, bool>> expression;
if(condition==null)
{
expression= (a =>
(SearchResult.Name==null || a.Name == SearchResult.Name)
);
}
else if(condition.Value == true)
{
expression= (a =>
(SearchResult.Name==null || a.Name == SearchResult.Name)
&& a.PersonType != null)
}
else if(condition.Value == false)
{
expression= (a =>
(SearchResult.Name==null || a.Name == SearchResult.Name)
&& a.PersonType == null)
}
I want to write the expression in one expression instead of using if else conditions. Can u plz help me in it?

Well you can do it with a conditional operator, but you need to specify the type of the expression tree for each lambda expression:
var expression = condition == null
? (Expression<Func<Person, bool>>) a => SearchResult.Name == null ||
a.Name == SearchResult.Name
: condition.Value
? (Expression<Func<Person, bool>>) a => (SearchResult.Name == null ||
a.Name == SearchResult.Name) &&
a.PersonType != null
: (Expression<Func<Person, bool>>) a => (SearchResult.Name == null ||
a.Name == SearchResult.Name) &&
a.PersonType == null;
But assuming you're going to use this with a LINQ query, you'd be much better off with something like:
var query = foo.Where(a => SearchResult.Name == null ||
a.Name == SearchResult.Name);
if (condition != null)
{
query = condition.Value ? query.Where(a => a.PersonType != null)
: query.Where(a => a.PersonType == null);
}
As an aside, I'd strongly advise you to avoid writing mutable structs or using public fields.

You could shorten as:
expression = a =>
(SearchResult.Name == null || a.Name == SearchResult.Name) &&
(SearchResult.condition == null || Search.condition == (a.PersonType != null));

C# Linq syntax help - How can I exclude two values?

I have this linq query that works well (although it may be written better, pls say so if you notice something)
var qry = BenefitCodes
.Where(b => b.BenInterest != 'E'
&& (b.BenProductLine == CoverageProductLine || b.BenProductLine == null) )
.Select(b => b)
.OrderBy(b => b.BenDesc);
A new requirement came down the pipeline to exclude two BenCodes ( 1001, 1009), BenCodes is just another column in the SQL table.
Am I supposed to use some variation of ".Contains", I would have to do !Contains or something. Can anyone point me in the right direction?
Thanks,
~ck in San Diego

Yes, one way to handle this is the following (for brevity and readability, I am excluding the remainder of your query):
var excludedBenCodes = new List<int>() { 1001, 1009 };
var query = BenefitCodes.Where(b => !excludedBenCodes.Contains(b.BenCodes));
I believe this to be more readable and more maintainable than the alternative of adding a subclause b.BenCodes != 1001 && b.BenCodes != 1009 to your where clause.

You could just simply add another line to the Where clause and exclude every itm with a BenCodes of 1001 or 1009.
Like this:
var qry =
BenefitCodes
.Where(b =>
b.BenInterest != 'E' &&
(b.BenProductLine == CoverageProductLine || b.BenProductLine == null) &&
b.BenCodes != 1001 &&
b.BenCodes != 1009)
.Select(b => b)
.OrderBy(b => b.BenDesc);

This might make things a bit more readable, I'd change query to
var qry = BenefitCodes.Where(b => FitsCriteria(b)).OrderBy(b => b.BenDesc);
and add method
public bool FitsCriteria(BenefitCode b)
{
return b.BenInterest != 'E' &&
(b.BenProductLine == CoverageProductLine || b.BenProductLine == null) &&
b.BenCodes != 1001 &&
b.BenCodes != 1009;
}
Kindness,
Dan

var qry = BenefitCodes
.Where(b => b.Code != '1001'
&& b.Code != '1009'
&& b.BenInterest != 'E'
&& ( b.BenProductLine == CoverageProductLine
|| b.BenProductLine == null))
.OrderBy(b => b.BenDesc);
You don't even need the "Select" when you aren't using the LINQ syntax. as the Where and OrderBy methods already return your IQueryable.