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

Edit: Try that one:

MyObject myObject = new MyObject();
List<myAccount> myAccountsList = new List<myAccount>();

myAccountsList.Add(new myAccount() {AccountNumber = "123"};
myAccountsList.Add(new myAccount() {AccountNumber = "456"};

myObject.ListOfAccounts = myAccountsList;

var accountNumbers = myObject.ListOfAccounts.Select(a => a.AccountNumber);

var accountsQuery = orgContext.CreateQuery<customAccountEntity>()
                              .Where(a => accountNumbers.Contains(a.account_number));

foreach(var item in accountsQuery)
{
    Console.WriteLine("Id of record retrieved: " + a.Id.ToString());
}

Edit: if you query provider don't support Contains, build a Where condition with multiple OR, you can use predicate builder to make that easy

Answer 2

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<T> 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<customAccountEntity>();
// 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<Func<customAccountEntity, bool>>
var myLinqToCrmQuery =  from ax in myObject.ListOfAccounts
                        from cx in orgContext.CreateQuery<customAccountEntity>().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.

Answer 3

Instead of playing with predicates you could also simply use the join expression for filtering.

var myLinqToCrmQuery =  from ax in myObject.ListOfAccounts
                            join cx in orgContext.CreateQuery<customAccountEntity> on ax.AccountNumber equals cx.account_number                      
                            select cx;

Cheers, Lukasz