CODEWITHSUNDEEP
c#linqentity-framework
AlexW
AlexW

Reputation: 2591

How to add a where clause that looks for an array of values

I was wondering if i could use an array for the below instead of writing multiple ORs

from d in db.tblEquipments.Include(t => t.User).Include(t => t.ChangeLog).AsEnumerable()
                                    where (d.AssetType == "Laptop" || d.AssetType == "Workstation" || d.AssetType == "Mobile" d.AssetType == "Monitor" d.AssetType == "Other Peripheral" || d.AssetType == "Home Printer" || d.AssetType == "Home Router" || d.AssetType == "Removable Device")
                                            (d.Active == 1) && 
                                            (d.Deleted != 1 || d.Deleted == null) &&

Something like the below?

string[] arrItems = new string[] { "Laptop", "Workstation", "Mobile" }; etc
where (d.assetType == arrItems) &&
         (d.Active == 1) && ....

is that possible?

Upvotes: 0

Views: 53

Answers (2)

Cédric Bignon
Cédric Bignon

Reputation: 13022

Yes it is. You have two ways to do it. The trivial way:

from d in myQueryable
where (arrItems.Contains(d.assetType)) &&
      (d.Active == 1) && ....

The problem with the previous method is that it checks all pair (x in myEnumerable, y in arrItems) which leads to a complexity of O(n²)

And the best way, with a complexity of O(n):

from d in myQueryable
join arrItem in arrItems on d.AssetType equals arrItem
select d

Upvotes: 0

Sergey Berezovskiy
Sergey Berezovskiy

Reputation: 236208

Use Contains method:

from d in db.tblEquipments.Include(t => t.User).Include(t => t.ChangeLog).AsEnumerable()
where arrItems.Contains(d.AssetType) &&  // same as SQL operator IN
      (d.Active == 1) && 
      (d.Deleted != 1 || d.Deleted == null) &&

Also don't use AsEnumerable() it brings all filtering into memory (i.e. instead of transferring only required equipments you are transferring all equipments over the network, and filter them in computer memory).

Upvotes: 4

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