实体框架Linq SelectMany with condition

我一直在尝试一段时间找到一个合适的解决方案的linq查询我试图写。

在我的模型结构中，我有我的Item类，它包含一个PaymentRecords列表。我想要我的查询实现的是:

public class PaymentRecord
{
    public int PaymentRecordId { get; set; }
    [Required]
    public double PaymentAmount { get; set; }
    [Required]
    public DateTime DateOfPayment { get; set; }
    [Required]
    public bool FinalPayment { get; set; }
    [JsonIgnore]
    public Item Item{ get; set; }
}
public class Item
{
    public int ItemId { get; set; }
    public List<PaymentRecord> PaymentRecords {get; set;}
    ...various other properties
}   

选择所有Items，其中PaymentRecord列表匹配下面的条件(工作良好)，或者PaymentRecord为空，例如Items类没有PaymentRecord。有办法做到这一点吗?

var result = m_context.Item
            .SelectMany(
                x => x.PaymentRecords.Where(p => (p.FinalPayment == true
                                              && p.DateOfPayment >= _revenueStatementRequest.StartDate
                                              && p.DateOfPayment <= _revenueStatementRequest.EndDate)
                                              || p.FinalPayment != true),
                (x, p) => x
            )
            .ToList();

理想情况下，我想做下面的事情，但我还没有能够得到任何类似的工作:

var result = m_context.Item
            .SelectMany(
                x => x.PaymentRecords.Where(p => (p.FinalPayment == true
                                              && p.DateOfPayment >= _revenueStatementRequest.StartDate
                                              && p.DateOfPayment <= _revenueStatementRequest.EndDate)
                                              || p.FinalPayment != true)
                || x.PaymentRecords == null,
                (x, p) => x
            )
            .ToList();

从给出的答案工作后，我有这个:

 m_context.Item.Where(c => (!
                            c.PaymentRecords.Any(q => (q.FinalPayment &&
                                                            q.DateOfPayment >= _revenueStatementRequest.StartDate &&
                                                            q.DateOfPayment <= _revenueStatementRequest.EndDate)
                                                            || q.FinalPayment != true
                                                )
                            )
                    && (c..Type == Booked || c.Type == Reserved)
                    && (c.StartDate < _revenueStatementRequest.StartDate)
                    )

        List<Item> res = m_context.Items
                      .Where(c => !c.PaymentRecords
                                .Any(q => (q.FinalPayment && 
                                        q.DateOfPayment >=_revenueStatementRequest.StartDate &&
                                        q.DateOfPayment <= _revenueStatementRequest.EndDate)
                                        || !q.FinalPayment)
                            )
    //**EDIT**
    .Where(c => c.StartDate < _revenueStatementRequest.StartDate)
 //this is comment out, so we can better test on the more complex part of the query
  //.Where(c => c.Type == Booked || c.Type == Reserved)   
    .ToList();

var result = m_context.Item
                      .Where(x => !x.PaymentRecords.Any() ||
                                   x.PaymentRecords.Any(p => (p.FinalPayment == true
                                                        && p.DateOfPayment >= _revenueStatementRequest.StartDate
                                                        && p.DateOfPayment <= _revenueStatementRequest.EndDate)
                                                        || p.FinalPayment != true))
                      .ToList();