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

With IQueryable you can simply add conditions in steps:

int? reportingPeriod = ...;

IQueryable resultsQuery =         // don't use `var` here.
        ctx.dExp.Include("datLab");   

if (values != null)
   resultsQuery = resultsQuery.Where(exp => values.Contains(exp.datL.Lab_ID));

if (reportingPeriod.Hasvalue)
   resultsQuery = resultsQuery.Where(exp => exp.reportingPeriod == reportingPeriod.Value);

// additional .Where(), .OrderBy(), .Take(), .Skip() and .Select()

// The SQL query is made and executed on the line below
// inspect the string value in the debugger
List results = resultsQuery.ToList();