Only do Where condition if a value is passed in

Question

I have the following LINQ statement that does on where on the date and a LabID.

I\'m passing in a list of LABS and a date, however

Answer 1

Here are two ways to do that.

But first, please don't use a single lowercase l as an identifier. It is way too easy to confuse it with the number 1. More generally, stp using abbrevs in yr cde, it mks it hrdr to rd.

First technique:

var query = from lab in ctx.dExp.Include("datLab")
            where values == null || values.Contains(lab.datL.Lab_ID)
            where reportingPeriod == null || lab.reportingPeriod == reportingPeriod
            select lab;
var list = query.ToList();

Second technique:

IEnumerable query = ctx.dExp.Include("datLab");
if (values != null)
    query = query.Where(lab=>values.Contains(lab.datL.Lab_ID));
if (reportingPeriod != null)
    query = query.Where(lab=>lab.reportingPeriod == reportingPeriod);
var list = query.ToList();