For the following query:
var result = from sch in schemeDashboard
join exp in Expenditure on sch.schemeId equals exp.SchemeCode
into SchExpGroup
where sch.SectorDepartmentId == selectedDepartmentId &&
sch.YearCode == StateManager.CurrentYear
orderby sch.ADPId
select new
{
ModifiedAmounts = SchExpGroup.Select(a => a.ModifiedAmounts),
ProjectName = sch.schemeName,
ADPNo = sch.ADPId,
Allocation = sch.CurrentAllocation,
Expenditures = from expend in SchExpGroup
where expend.YearCode == StateManager.CurrentYear &&
expend.DepartmentId == selectedDepartmentId &&
InvStatus.Contains(expend.Status)
orderby expend.ADPId
group expend by expend.InvoiceId
};
I want to filter the above query on a condition so that result gives only those records where "ModifiedAmounts" are not null. I have tried as follow:
if (rbList2.SelectedIndex == 6)
{
result = result.Where(a => a.ModifiedAmounts != null));
}
but this gives error as:
Cannot compare elements of type
'System.Collections.Generic.IEnumerable`1'. Only primitive types,
enumeration types and entity types are supported.
Any suggestions as I am lost as how to rephrase the filtered query.
I think the problem is that ModifiedAmounts will never be null. Select will return an empty list. Unless SchExpGroup is null in which case you will get a null reference exception.
Try changing your code to
result = result.Where(a => a.ModifiedAmounts.Any());
if (rbList2.SelectedIndex == 6)
{
result = result.Where(a => a.!ModifiedAmounts.Any());
}
Related
I wrote a query and worked on LINQPAD
from x in FacilityData
from y in FavInformation
where y.UserID == 1 && x.ID == y.FacilityID
select new
{
xID = x.ID,
xDistrictName = (from y in _Ilcelers
where y.ID == x.DistrictID
select y.IlceAd).FirstOrDefault(),
xName = x.Name,
Value = (from o in Tags
from p in Table_tags
where o.Prefix != null && o.Prefix == p._NAME && o.Facility == y.FacilityID
orderby p.İd descending
select new
{
FType = o.TagType,
Name = o.TagsName,
Value = p._VALUE,
Time = p._TIMESTAMP
}).Take(Tags.Count(h => h.Facility == y.FacilityID))
}
result
the result is perfect
but does not work in visual studio,
Value = (from o in DB.Tags
from p in DB.table_tags
where o.Prefix != null && o.Prefix == p.C_NAME && o.Facility == 11
orderby p.id descending
select new
{
FType=o.TagType,
Name = o.TagsName,
Value = p.C_VALUE,
Time = p.C_TIMESTAMP
}).Take(Tags.Count(h => h.Facility == y.FacilityID))
and it gives an error.
I guess the part with .Take() doesn't work because it's linq to EF.
error:
Limit must be a DbConstantExpression or a Db Parameter Reference Expression. Parametre name: count]
error image
thank you have a good day
Not sure but I will just throw it in. If you are talking about linq to ef/sql, it is possible they dont know a thing about C#. If take() would be the problem try to get the select result local first by doing .tolist(). Afterwards use your take funtion.
.ToList().Take(Tags.Count(h => h.Facility == y.FacilityID))
My Code :
IEnumerable<DataRow> whrRowEnum;
whrRowEnum = from r in dtInput.AsEnumerable()
where r.Field<string>("EMP_DEP") == "DEP1"
orderby EMP_DEP
select r;
The above code is working fine due to hard coded where condition, but In run-time I need to add multiple where condition in my linq query like r.Field("EMP_DEP") == "DEP1" && r.Field("EMP_ID") == "EMP1"
You can use lambda syntax to compose your query based on conditions:
IEnumerable<DataRow> query = dtInput.AsEnumerable();
if (condition1)
query = query.Where(r => r.Field<string>("EMP_DEP") == "DEP1");
if (condition2)
query = query.Where(r => r.Field<string>("EMP_ID") == "EMP1");
var whrRowEnum = query.OrderBy(r => r.Field<string>("EMP_DEP"));
Another option is adding conditions to query filter
whrRowEnum = from r in dtInput.AsEnumerable()
where (!condition1 || (r.Field<string>("EMP_DEP") == "DEP1")) &&
(!condition2 || (r.Field<string>("EMP_ID") == "EMP1"))
orderby EMP_DEP
select r;
public GetApplicants(string Office,
int Id,
List<int> cfrparts,
List<int> expertiseAreaIds,
List<int> authIds,
List<int> specIds)
{
bool isAuthIdsNull = authIds == null;
authIds = authIds ?? new List<int>();
bool isSpecIdNull = specIds == null;
enter code here
var query =
from application in Apps
from cfr in application.cfr
from exp in cfr.Aoe
from auth in exp.Auth
from spec in exp.Special
where application.Design.Id == 14
where (iscfrpart || cfrPartIds.Contains(cfr.CfrP.Id))
where (isexp || expertiseAreaIds.Contains(exp.Aoe.Id))
where (isAuthIdsNull || authIds.Contains(auth.Auth.Id))
where (isSpecIdNull || specIds.Contains(spec.Special.Id))
where application.Office.Text.Contains(Office)
where application.D.Id == Id
select application.Id;
How can i make this query dynamic. If I have only Id and Office values It should still give me the resultset based on the avaliable values. Cureently its not giving me the result.
Instead of doing multiple calls to where, use &&
var query =
from Apps
where (iscfrpart || cfrPartIds.Contains(Apps.cfr.CfrP.Id))
&& (isexp || expertiseAreaIds.Contains(Apps.cfr.Aoe.Id))
&& (isAuthIdsNull || authIds.Contains(Apps.cfr.Aoe.Auth.Id))
&& (isSpecIdNull || specIds.Contains(Apps.cfr.Aoe.Special.Id))
&& Apps.Office.Text.Contains(Office)
&& Apps.D.Id == Id
select application.Id;
Additionally, this clause application.D.Id == 14 will cause 0 results when combined with this one: application.D.Id == Id if the passed in Id does not equal 14. You may want to delete that first clause.
Edit: updated your from clause, but I still don't think this will work because your table structure seems off.
Dynamic querying isn't required to solve this problem. You can write code that constructs the query.
Make a method that constructs your filter based on the information you have.
public Expression<Func<Application, bool>> GetFilterForCFR(List<int> cfrParts)
{
if (cfrParts == null || !cfrParts.Any())
{
return app => true;
}
else
{
return app => app.cfr.Any(cfr => cfrParts.Contains(cfr.cfrPId));
}
}
Then, you can construct the query using the expression.
var query = Apps;
var cfrFilter = GetFilterForCFR(cfrParts);
query = query.Where(cfrFilter);
//TODO apply the other filters
var finalquery = query.Select(app => app.Id);
my linq query returns duplicate records like below, how i have to use distinct keyword in this linq query.
var draft_recieved = from df in _DataContext.tblDrafts
from dfBody in _DataContext.DraftBodies
from sendUser in _DataContext.tblSends
where (df.DraftId == dfBody.DraftID) && (df.DraftId == sendUser.DraftId) &&
(sendUser.ToEmailId == (Guid)Membership.GetUser().ProviderUserKey)
select new
{
subject = dfBody.Subject,
draftid = df.DraftId
};
.Distinct() has to be applied as an extension method.
var draft_recieved = (from df in _DataContext.tblDrafts
from dfBody in _DataContext.DraftBodies
from sendUser in _DataContext.tblSends
where (df.DraftId == dfBody.DraftID) && (df.DraftId == sendUser.DraftId) &&
(sendUser.ToEmailId == (Guid)Membership.GetUser().ProviderUserKey)
select new
{
subject = dfBody.Subject,
draftid = df.DraftId
}).Distinct();
in this example code
public Company GetCompanyById(Decimal company_id)
{
IQueryable<Company> cmps = from c in db.Companies
where c.active == true &&
c.company_id == company_id
select c;
return cmps.First();
}
How should I handle if there is no data in cmps?
cmps will never be null, so how can I check for non existing data in a LINQ Query?
so I can avoid this
'cmps.ToList()' threw an exception of type ... {System.NullReferenceException}
when transforming it into, for example, a List
GetCompanyById(1).ToList();
Do I always need to wrap it up in a try catch block?
You can use Queryable.Any() (or Enumerable.Any()) to see if there is a member in cmps. This would let you do explicit checking, and handle it however you wish.
If your goal is to just return null if there are no matches, just use FirstOrDefault instead of First in your return statement:
return cmps.FirstOrDefault();
What about applying .Any or .Count() ?
Here's an example on MSDN
List<int> numbers = new List<int> { 1, 2 };
bool hasElements = numbers.Any();
Console.WriteLine("The list {0} empty.",
hasElements ? "is not" : "is");
Or just use the ?: operator
return myExample.Any() ? myExample.First() : null;
This will return the first one if there is one, or null if there isn't:
return (from c in db.Companies
where c.active == true &&
c.company_id == company_id
select c).FirstOrDefault();
Try return cmps.Count()==0?null:cmp.First()
That way if it is null it will simply return a null Company and if its not then it will return the first one in the list.
Check out http://en.wikipedia.org/wiki/Ternary_operation
var context = new AdventureWorksLT2008Entities();
var cust = context.Customers.Where(c => c.CustomerID == 1);
if (cust.Any())
{
Customer c = cust.First();
}