I have a case where a customer can have many contacts and a contact can be assigned to many customers.

Currently I have a page for each customer, on load I get all the contacts (a publishing page for each contact) for the customer. Currently I have this code which works but performs badly:

var lookups = new SPFieldLookupValueCollection();
foreach (var customer in customers)
    var contactLookups = new SPFieldLookupValueCollection(customer["Contacts"].ToString());

var contacts = web.Lists["Pages"].Items.Cast<SPListItem>()
    .Where(a => lookups.Exists(value => value.LookupId == a.ID);

It performs badly because the Pages library contains the PublishingPageContent column which is a lot of HTML sent over the wire for each contact.

I need to convert this piece of code to a CAML query and it works fine if I have a SPFieldLookupValue.LookupId but now I can have multiple, i.e. a SPFieldLookupValueCollection.

How can I use a condition like this: .Where(a => lookups.Exists(value => value.LookupId == a.ID); in a CAML query?

Do I need to use <In> and append a string with value for each id in the lookup collection, i.e. build like so:

    <FieldRef Name='ID' />
       <Value Type='Counter'>354</Value>
       <Value Type='Counter'>353</Value>
  • Looks like I answered by own question but can't find the delete link anymore.
    – Peter
    Aug 5, 2013 at 5:28
  • I think you did! Add the last part as an answer, with a short line about why. Then this question will be helpful to others in the future :) Aug 5, 2013 at 5:40

1 Answer 1


Ok so it looks like I answered by own question, I changed it to use a CAML query like so:

StringBuilder sb = new StringBuilder();

foreach (var lookup in lookups)
    sb.AppendLine(string.Format("<Value Type='Counter'>{0}</Value>", lookup.LookupId.ToString()));

SPQuery query = new SPQuery();
query.Query = @"<Where>
                        <FieldRef Name='Office' />
                        <FieldRef Name='_ModerationStatus' />
                        <Value Type='ModStat'>0</Value>
                        <FieldRef Name='ID' />
                            + sb.ToString() +

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