Append OR subquery in Linq - linq

Question

I am trying to build a simple search against some entities (EF4, if that makes any difference). Passed into my search query is a list of criteria objects. The crieteria object looks like this:
public class ClaimSearchCirtieria
{
public Guid? FinancialYear { get; set; }
public bool AllClaimants { get; set; }
public IList<Guid> ClaimantIds { get; set; }
public bool AllExpenseCategories { get; set; }
public IList<ExpenseCategoryAndTypeCriteria> EpenseCategoryAndTypes { get; set; }
}
And the ExpenseCategoryAndTypeCriteria
public class ExpenseCategoryAndTypeCriteria
{
public Guid ExpenseCategory { get; set; }
public bool AllTypesInCatgeory { get; set; }
public IList<Guid> ExpenseTypes { get; set; }
}
Searching on financial years and claimants needs to be an AND query, then I need the expense categories and expense types to be appended as an OR sub query.
In essence I'm trying to do:
select *
from claims
where <financial year> AND <Claimants> AND (expense type 1 OR expense type 2 or expense category X)
So far I've got this:
public PagedSearchResult<Claim> Search(ClaimSearchCirtieria searchCriteria, int page, int pageSize)
{
var query = All();
if (searchCriteria.FinancialYear.HasValue)
{
query = from claim in query
where claim.FinancialYearId == searchCriteria.FinancialYear
select claim;
}
if (!searchCriteria.AllClaimants)
{
query = from claim in query
where searchCriteria.ClaimantIds.Contains(claim.ClaimantId)
select claim;
}
if (!searchCriteria.AllExpenseCategories)
{
foreach (var item in searchCriteria.EpenseCategoryAndTypes)
{
if (item.AllTypesInCatgeory)
{
//Just search on the category
query = query.Where(claim =>
(from transaction in claim.ClaimTransactions
where item.ExpenseCategory == transaction.ExpenseType.ExpenseCategoryId
select transaction).Count() > 0
);
}
else
{
//Search for the specified types
query = query.Where(claim =>
(from transaction in claim.ClaimTransactions
where item.ExpenseTypes.Contains(transaction.ExpenseTypeId)
select transaction).Count() > 0
);
}
}
}
return PagedSearchResult<Claim>.Build(query, pageSize, page);
}
What I'm currently seeing is that the last expense category requested is the only expense category I get results for. Also, looking at the code, it looks like I would expect this to be building a series of AND queries, rather that the required OR.
Any pointers?

Answer 1

You can do this with LINQKit's PredicateBuilder. You need to use AsExpandable() when composing Entity Framework queries.