CODEWITHSUNDEEP
c#countiqueryable
Beytan Kurt
Beytan Kurt

Reputation: 2263

IQueryable queried data count

I am trying to get the count of the items as I'm applying a query to a IQueryable.

I'am trying to do it like:

this.lblSth.Text = new Repository<Sth>().GetAll().Where(p => p.PersonId == personId).ToList().Count().ToString();

I think this gets all the data across the condition and takes the objects, then it takes the count; so I'm curious if for example I'd just take the Id columns and cast it to the list or some other smart way; that count operation would be quicker?

Info: GetAll() => It's a repository pattern method that returns IQueryable objects T from linqToSql data entity.

I'm open to all types of different ideas. Thanks

Upvotes: 2

Views: 1075

Answers (3)

scartag
scartag

Reputation: 17680

I think the call to Where and ToList is redundant. see below.

this.lblSth.Text = new Repository<Sth>().GetAll().Count(p => p.PersonId == personId).ToString();

Upvotes: 1

TGH
TGH

Reputation: 39268

ToList() will execute the query and turn your IQUeryable into IEnumerable. I would call the count on the where clause. That way the Count will become part of the end query

Upvotes: 0

svick
svick

Reputation: 244928

If you want to do this quicker, just don't call ToList():

this.lblSth.Text = new Repository<Sth>().GetAll()
                                        .Where(p => p.PersonId == personId)
                                        .Count()
                                        .ToString();

This way, (assuming it's an SQL-backed IQueryable<T>) it will execute a query like SELECT COUNT(*) FROM …, not SELECT * FROM … like your approach. And this query should be much faster.

Upvotes: 1

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