LINQ to Dynamics CRM Query filtering records locally

Question

I have written a Linq to CRM query using CRM 2011 RC (v5) LINQ-to-CRM provider. I have a locally declared List which I want to join to a CRM entity and I want the q

Answer 1

After a lot of head banging and research I have resolved the issue by using Predicate Builder and LINQKit. I need to create an Or based predicate using the keys in my local List then pass the predicate to the Where LINQ extension method. Importantly, I need to call the AsExpandable extension method exposed by LINQKit. So my code would look like this:

var predicate = PredicateBuilder.False();
// Loop through the local List creating an Or based predicate
foreach (var item in myAccountsList)
{
    string temp = item.AccountNumber;
    predicate = predicate.Or (x => x.customCrmEntityAttribute == temp);
}
// The variable predicate is of type Expression>
var myLinqToCrmQuery =  from ax in myObject.ListOfAccounts
                        from cx in orgContext.CreateQuery().AsExpandable().Where(predicate)
                        where ax.AccountNumber == cx.account_number
                        select cx;

foreach (resultItem in myLinqToCrmQuery)
{
    Console.WriteLine("Account Id: " + resultItem.Id);
}

The above code will run a SQL Statement on the CRM Server like this:

SELECT a.*
FROM customAccountEntity AS a
WHERE a.account_number = '123' OR a.account_number = '456'

This means I can create a dynamic where clause at runtime and know that my query will run the filtering logic on the CRM SQL Server. Hope this helps somebody else.