使用包含（如运算符）过滤实体结果时出错

Question

能否请您帮我使用 contains（如运算符）来归档结果，如下所示...

Public Function GetFromCacheByParentID(ParentID As String, Criteria As String) As List(Of tbl_equip_master) 
Dim RelatedData = _RelatedData.GetFromCache
Dim EquipMaster = Me.GetFromCache
return (From e In EquipMaster, r In RelatedData Where r.linked_for = "EQP" And e.global_id = r.child_id And r.parent_id = ParentID And (e.tag_no.Contains(Criteria) Or e.object_name.Contains(Criteria) Or e.object_type.Contains(Criteria)) Select e)
End Function

我的意图是从兑现数据中调用 2 个结果并尝试使用 contains

加入和过滤

但是我在“.contains”上遇到错误。

Answer 1

我找出问题所在，原因是 "e.object_name value is Nothing" - 来自 sql 服务器的数据。所以代码 "e.object_name.Contains(Criteria)" 抛出错误...

另一个问题是提出我们如何避免这种情况...请有任何想法...

Answer 2

所有问题已通过使用以下代码捕获 "null" 值

解决

Public Function GetFromCacheByParentID(ParentID As String, Criteria As String) As List(Of tbl_equip_master) Dim _RelatedData As IRelatedDataV2 = New RelatedDataV2 Dim RelatedData = _RelatedData.GetFromCache Dim EquipMaster = Me.GetFromCache Return (From e In EquipMaster, r In RelatedData Where r.linked_for = "EQP" And e.global_id = r.child_id And r.parent_id = ParentID And (e.tag_no.Contains(Criteria) _ Or (Not IsNothing(e.object_name) AndAlso e.object_name.Contains(Criteria))) Select e).ToList End Function

使用包含（如运算符）过滤实体结果时出错

Getting an error while filtering an entity results using contains (like operator)

entity

linq-to-objects