Question

我想在结算时过滤附件：

var billing = db.Billings
                .Include(b => b.Client)
                .Include(b => b.Attachments.Where(a => a.WorkflowStateID == workflowStateID))
                .Where(b => b.BillingID == id)
                .FirstOrDefault();

结算实体：

public partial class Billing
    {
        public Billing()
        {
            this.Attachments = new HashSet<Attachment>();
        }

        public long BillingID { get; set; }
        public int ClientID { get; set; }

        public virtual ICollection<Attachment> Attachments { get; set; }
        public virtual Client Client { get; set; }
    }

但是它会出错

The Include path expression must refer to a navigation property defined on the type.
Use dotted paths for reference navigation properties and the Select operator for 
collection navigation properties

如何在include上使用where子句？我想要实现的是如果我在查询sql中翻译：

select * 
from Billing b
    inner join Client c on b.ClientID = c.ClientID
    inner join (select * from Attachment a where a.WorkflowStateID = @workflowStateID) t on b.BillingID = t.BillingID
where b.BillingID = @billingID

Answer 1

如上所述，不允许在Include方法中使用Where。据我所知，不可能过滤这样的导航属性。你可以做的是使用投影

var billing = db.Billings
    .Where(b => b.BillingID == id)
    .Select(b => new {
        Billing = b,
        BillingClient = b.Client
        FilteredAttachments = b.Attachments.Where(a => a.WorkflowStateID == workflowStateID)
    })
    .FirstOrDefault();

使用where子句包含生成错误“包含路径表达式必须引用在类型上定义的导航属性”

1 个答案: