Linq-Sql IQueryable<T> and chaining OR operations

Question

I'm trying to simulate:

WHERE x.IsActive = true OR x.Id = 5

The following causes 'AND' to be used... how do I simulate an 'OR' condition with IQueryable (qry) and my nullable int, given that other filtering might be involved as with the IsActive filter here?

            if (onlyActiveItems) //bool
            {
                qry = qry.Where(x => x.IsActive == true);
            }

            if (whenSpecifiedMustIncludeRecordWithThisId.HasValue) //int?
            {
                qry = qry.Where(x => x.Id == whenSpecifiedMustIncludeRecordWithThisId.Value);
            }

I have considered union but its seems the answer to this should be much simpler.

---

This is one solution which gets around the problem I get with "Nullable object must have a value" when trying the combined all in one answer. What causes the nullable to be evaluated when it is null otherwise?

            if (whenSpecifiedMustIncludeRecordWithThisId.HasValue)
            {
                qry = qry.Where(x => (!onlyActiveItems || (onlyActiveItems && x.IsActive)) || x.Id == whenSpecifiedMustIncludeRecordWithThisId.Value);
            }
            else
            {
                qry = qry.Where(x => (!onlyActiveItems || (onlyActiveItems && x.IsActive)));
            }

It seems also in some cases the use of the nullable's .Value property makes a difference as seen in another question of mine here http://stackoverflow.com/questions/1634992/linq-to-sql-int16-gets-converted-as-int32-in-sql-command

Answer 1

Try this:

qry = qry.Where(x => (onlyActiveItems
                      ? x.IsActive
                      : false) ||
                     (whenSpecifiedMustIncludeRecordWithThisId.HasValue
                      ? x.Id == whenSpecifiedMustIncludeRecordWithThisId
                      : false) ||
                     (!onlyActiveItems && !whenSpecifiedMustIncludeRecordWithThisId.HasValue));

Note that we're comparing an int? to an int, not two ints.

I am assuming here that the point of the query is to filter out if certain conditions are met.

• If onlyActiveItems is true, it verifies whether the IsActive field is true
• If whenSpecifiedMustIncludeRecordWithThisId.HasValue is true it verifies whether the value matches the Id field
• If both are true it will logically OR the conditions
• If both are false all records are displayed (if this is not the intent, you can remove the last condition)

Answer 2

When working with "int?" I usually compare them using object.Equals(i1, i2), for example

from r in cxt.table
where object.Equals(r.column, nullableInt)
select r

This avoids all nullable issues.