I have simple Linq statement (using EF4)
var efCars = (from d in myentity.Cars
where d.CarName == inputCar.CarName
&& d.CarIdNumber == inputCar.IdNumber
&& d.Make == inputCar.Make
select d.Car);
I want it to be smarter so that it will only query across one or more of the 3 fields IF they have values.
I can do a test before, and then have a separate linq statement for each permutation of valyes for inputcar
(i.e. one for all 3, one for if only carname has a value, one for if carname AND CarIdNumber has a value etc etc)
but there must be a smarter way
Thanks!
If "has no value" means null then you can use the null coalescing operator ?? to say take the first value if populated, otherwise take the second:
var efCars = (from d in myentity.Cars
where d.CarName == (inputCar.CarName ?? d.CarName
&& d.CarIdNumber == (inputCar.IdNumber && d.CarIdNumber)
&& d.Make == (inputCar.Make && d.Make)
select d.Car);
This basically says if a value exists it must match, otherwise treat it as matching
However if instead you're saying "when a special value (empty string) ignore it, otherwise match" then you can do one of two approaches (or possibly more!):
where (inputCar.CarName == "" || d.CarName == inputCar.CarName)
where (string.IsNullOrEmpty(inputCar.CarName) || d.CarName == inputCar.CarName)
For performance (when dealing with database queries) it can sometimes be beneficial to let EF generate queries based on the filters, instead of using one generic query. Of course you will need to profile whether it helps you in this case (never optimize prematurely), but this is how it would look if you dynamically build your query:
var efCars =
from car in myentity.Cars
select car;
if (inputCar.CarName != null)
{
efCars =
from car in efCars
where care.CarName == inputCar.CarName
select car;
}
if (inputCar.IdNumber != null)
{
efCars =
from car in efCars
where care.CarIdNumber == inputCar.IdNumber
select car;
}
if (inputCar.Make != null)
{
efCars =
from car in efCars
where care.Make == inputCar.Make
select car;
}
where (inputCar.CarName != null || d.CarName == inputCar.CarName) &&...
Related
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());
}
I have a LINQ query which works fine as for stand alone lists but fails for CRM
var lst = new List<bool?>();
lst.Add(null);
lst.Add(true);
lst.Add(false);
bool IsWet = false;
var newlst = from exch_HideVoiceSignature in lst where
(((exch_HideVoiceSignature!=null && exch_HideVoiceSignature==false
|| exch_HideVoiceSignature== null) )&& !IsWet) select exch_HideVoiceSignature;
newlst.Dump();
var question = from q in exch_questionSet where ((q.exch_HideVoiceSignature != null
&& q.exch_HideVoiceSignature.Value == 0 )|| q.exch_HideVoiceSignature == null )
&& !IsWet select q.exch_HideVoiceSignature;
question.FirstOrDefault().Dump();
As you can see I can pass the variable IsWet to LINQ query for a standard list fine and get values for first list. But when I execute the same for second list, I get the following error
Invalid 'where' condition. An entity member is invoking an invalid property or method
The CRM LINQ provider won't support the evaluation you attempting. It only supports evaluation of where criteria is evaluating an entity field.
That's not a problem. Since you want the LINQ query to only use the where clause if IsWet is false (correct me if I'm wrong on that.) So we simply do the evaluation to determine if the where clause should be added or not. Then execute your query.
var question = from q in exch_questionSet
select q.exch_HideVoiceSignature;
if (!IsWet)
{
question.Where(x => ((x.exch_HideVoiceSignature != null
&& x.exch_HideVoiceSignature.Value == 0) || x.exch_HideVoiceSignature == null));
}
question.FirstOrDefault().Dump();
I am constantly confronted with that problem.
Try to "detach" (for example call .ToArray()) your query (while it is "clear") from CRM and then filter query using external parameter. This should help.
var question =
(from q in exch_questionSet
where (
(q.exch_HideVoiceSignature != null && q.exch_HideVoiceSignature.Value == 0 ) ||
q.exch_HideVoiceSignature == null )
select q.exch_HideVoiceSignature
).ToArray().Where(q => !IsWet);
question.FirstOrDefault().Dump();
UPDATE
If you are using IsWet flag to control blocks of conditions (enable and disable them from the one point in the code) then probably you may be interested in class named PredicateBuilder which allows you to dynamically construct predicates.
Just because I had an existing query with lot of other joins etc. and I wanted to pass this additional parameter to it I ended up using a var statement which dumps the rows to a list and applies the where clause in the same statement
bool IsWet =true ;
var question = ...existing query ...
select new {
...existing output ...,
Wet =q.exch_HideVoiceSignature != null &&
q.exch_HideVoiceSignature.Value == 119080001,
Voice = q.exch_HideVoiceSignature == null ||
(q.exch_HideVoiceSignature != null &&
q.exch_HideVoiceSignature.Value == 119080000) ,
}
;
var qq = IsWet ?
question.ToList().Where(X=> X.Wet ) :
question.ToList().Where(X=> X.Voice );
qq.FirstOrDefault().Dump();
I have a problem with Contains in linq to sql query as below:
public IAuditRecord[] Fetch(SearchConditions searchConditions)
{
IAuditRecord[] searchedList = (from rows in _dbContex.AuditTrails
where
(searchConditions.Owner == null || searchConditions.Owner == 0) ? true : rows.Owner == searchConditions.Owner
&&
/*This line cannot compile when ActionIDs array is empty*/
(searchConditions.ActionIDs != null && searchConditions.ActionIDs.Length != 0) ? searchConditions.ActionIDs.Contains(rows.UserActionID) : true
&& ((searchConditions.StartDate != null && searchConditions.EndDate != null) ? (rows.TimeStamp >= searchConditions.StartDate && rows.TimeStamp <= searchConditions.EndDate)
: (searchConditions.StartDate != null && searchConditions.EndDate == null) ? rows.TimeStamp >= searchConditions.StartDate : (searchConditions.StartDate == null && searchConditions.EndDate != null) ? (rows.TimeStamp <= searchConditions.EndDate)
: true)
select rows).ToArray();
return searchedList;
}
This query executes perfectly if searchCondition.ActionIDs array is not null or empty,
but when i pass the ActionIDs array as null the query cannot be compiled.
So the main question is Why contains cannot work when ActionIDs array is null?
You're building an IQueryable, which defines how to query for something, not actually doing it. To do this it builds an Expression, which defines all the query intents and can later be called to actually get the data. If you were using LINQ-to-Objects, this would likely work since it would likely call searchConditions.ActionIDs != null first, then know that it doesn't have to attempt to execute the second portion. Linq-to-Entities/SQL, etc. don't have that benefit.
Long story short, you can either do:
searchConditions.ActionIDs = searchConditions.ActionIDs ?? new int[];
Or do a different query if its null, like:
var query = _dbContext.AuditTrails;
if(searchConditions.ActionIDs != null && searchCondition.ActionIDs.Length != 0)
{
query = // Further filtered query where ActionIDs are taken into account.
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);
I have the following query:
var req= (from tl in resultlist
where (tl.Message.StartsWith("Do not return") && tl.Type == "Int") &&
(tl.Note.StartsWith("Do no return") && tl.Type == "Ext")
select tl).Any();
I am trying to see if there are records where Message starts with "Do not return" and Type is "Int"
and there is another message where Note start with "Do no return" and Type is "Ext".
Seems like my query is wrong as not returning anything.
You probably want to change that && to a || as one of the comments (Joachim Isaksson) above points out. You are asking for a property (.Type) to exist in 2 different ways on one entity. That is not possible.
Try
req= (from tl in resultlist
where (tl.Message.StartsWith("Do not return") && tl.Type == "Int") ||
(tl.Note.StartsWith("Do no return") && tl.Type == "Ext")
select tl).Any();
var intMessages = from tl in resultlist
where tl.Message.StartsWith("Do not return")
&& tl.Type == "Int"
select tl;
var extMessages = from tl in resultlist
where tl.Message.StartsWith("Do not return")
&& tl.Type == "Ext"
select tl;
var intAndExtMessages = intMessages.Any() && extMessages.Any();
This will ensure that in the result set there are some "Do not return" messages which start with "Int" AND in the same result set are some other messages which start with "Ext"
The function (the condition in query) checks if the source element meets some requirements so if you check for the same object's Type to be "Int" and "Ext" is not possible, since can't have two string values in the same time.
On the other hand you need to find out if in the resultlist exist items of two different types or for two exclusive conditions, so this it can't be done in a single iteration (each LINQ query is an iterator in the end..).