Question

Let’s say we have a description field on my form with optional check boxes. The check boxes represent which fields to search when doing the lookup. Right now I have a matrix of look ups that call their unique version of where clause. It works but I think it smells a bit.

Here is an excerpt

    // Look for part numbers decide how many fields to search and use that one.
    // 0 0 X
    if (!PartOpt[0] && !PartOpt[1] && PartOpt[2])
    {
     query = query.Where(p => (p.PartNumAlt2.Contains(partSearchRec.inventory.PartNum)));
    }
    // 0 X 0
    if (!PartOpt[0] && PartOpt[1] && !PartOpt[2])
    { 
      query = query.Where(p => (p.PartNumAlt.Contains(partSearchRec.inventory.PartNum)));
    }
    // 0 X X
    if (!PartOpt[0] && PartOpt[1] && PartOpt[2])
    {
      query = query.Where(p => (p.PartNumAlt.Contains(partSearchRec.inventory.PartNum)
        || p.PartNumAlt2.Contains(partSearchRec.inventory.PartNum)));
    }
    // X 0 0
    if (PartOpt[0] && !PartOpt[1] && !PartOpt[2])
    {
      query = query.Where(p => (p.PartNum.Contains(partSearchRec.inventory.PartNum)));
    }
     . . .

This goes on for a while and seems to be prone to coding errors. In each case we are looking for the same information in any of the selected fields. If I was doing this in SQL I could simply build up the WHERE clause as needed.

Answer 1

Once again I rubber ducked my way to an answer. Rather than throw the question away, here is what I came up with. Is it efficient?

if (partSearchRec.optPartNum || partSearchRec.optAltPartNum1 || partSearchRec.optAltPartNum2)
{
  query = query.Where(p => (
       (partSearchRec.optPartNum && p.PartNum.Contains(partSearchRec.inventory.PartNum))
    || (partSearchRec.optAltPartNum1 && p.PartNumAlt.Contains(partSearchRec.inventory.PartNum))
    || (partSearchRec.optAltPartNum2 && p.PartNumAlt2.Contains(partSearchRec.inventory.PartNum))));
}

Basically if any of the check boxes are set we will execute the query. Each line of the query will be processed only if the check box was checked. If the left side of an AND is false it doesn’t process the right.

This is an aera that Delphi’s with statement would be handy. I also learned that you can’t use an array inside the LINQ statement.