foreach中的条件LINQ查询

Question

I have a multiselection box and I would like to iterate over the selected items and do a linq query, but I'm not sure how to write it. This is what I have so far:

if (lbStateLegislation.Items.Count > 0)
{
  foreach (ListItem li in lbStateLegislation.Items)
    attributes = vdc.attributes.Where(a => a.fieldvalue == li.Value).ToList();
}

I basically need to construct an OR query, so it is selecting from the collection where there are values for each of the selected items. I think, as it's written now, it is doing an AND query.

Answer 1

Just use the Contains extension method. Linq2Sql will translate it as an IN clause:

var inValues = lbStateLegislation.Items.Select(s => s.Value);
vdc.attributes.Where(a => inValues.Contains(a.fieldvalue));

You may be able to combine the two statements into one, but I will leave that for you to try as I'm not positive that it will work as a single statement.

HTH

Answer 2

var attributes=
  vdc.attributes.Where(q=> 
                   lbStateLegislation.Items.Any(o=> o.Value == q.fieldValue))
                 .Select(o=> o);