Linq2Sql内部列表对象上的管道和过滤器

我正在使用带有管道/过滤器的Linq2Sql。我的数据库由账户和交易表组成,其中每个交易行都链接到一个账户。

显示账户时,我想显示账户及其所有交易。很简单。现在,我试图限制例如/accounts/4/{年}/{月}/{日}显示的交易。

Account a = AccountsRepository.GetAccounts()
               .WithID(id)
               .FilterTransactions(year, month, day)
               .SingleOrDefault();

exec sp_executesql N'SELECT [t0].[ID], [t0].[BankName], 
[t0].[BankCode], [t0].[CardNumber], [t0].[Locale]
FROM [dbo].[Accounts] AS [t0]
WHERE [t0].[ID] = @p0',N'@p0 int',@p0=1

exec sp_executesql N'SELECT [t0].[ID], [t0].[AccountID], 
[t0].[Date], [t0].[Description], [t0].[Amount]
FROM [dbo].[Transactions] AS [t0]
WHERE [t0].[AccountID] = @p0',N'@p0 int',@p0=1

public static IQueryable<Account> FilterTransactions(
this IQueryable<Account> qry, int? year, int? month, int? day)
{
    ...loop through each Account
    a.Transactions = a.Transactions
    .Where(t => t.Date.Year == year);
}

但是,a.Transactions是一个EntitySet,Where返回一个IEnumerable。