CODEWITHSUNDEEP
linqienumerable
sesamii seed
sesamii seed

Reputation: 739

how to get the linq list having Ids from IEnumerable<Object>

The code below userModel.Carriers is the type of IEnumerable<CarrierModel>. userModel.Carriers has a list of carriers having Ids. With those Ids, I want to get CarrierDivision usign linq. But, I can't get it right because linq sqlexpression is not compatible with IEnumerable expression. 

userModel.Carriers = carriersForRegion.Select(carrier => Mapper.Map<CarrierModel>(carrier))
                    .ToList();

var carrierDivision = from c in db.CarrierDivision where c.Contains();

Upvotes: 0

Views: 704

Answers (1)

Fabio
Fabio

Reputation: 32445

collection.Contains will generate .. WHERE CarrierId IN (1, 2, 3) sql query

var carrierIds = userModel.Carriers.Select(carrier => carrier.Id).ToArray();

var divisions = db.CarrierDivision
    .Where(division => carrierIds.Contains(division.CarrierId))
    .ToArray();

In case db.CarrierDivision returns IEnumerable(not database), then I would suggest to create HashSet of carrier ids. 

var carrierIds = userModel.Carriers.Select(carrier => carrier.Id).ToHashSet();

var divisions = db.CarrierDivision
    .Where(division => carrierIds.Contains(division.CarrierId))
    .ToArray();

With HashSet search executed without extra enumerations - O(1)

Upvotes: 1

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