实体框架 - 查询可空列的问题 [英] Entity Framework - Problem with querying nullable column

问题描述

pre> AND（CAST（[Extent1]。[PositionEffect] AS int）= @ p__linq__3）


=> @ p__linq__3 = NULL

如果我手动运行该查询，则不会显示任何结果。但是，当我用以下代码替换查询：

  AND（[Extent1]。[PositionEffect] IS @ p__linq__3）
  

它会显示预期的结果。

我的C＃查询如下所示：

  context.Allocations.Where（x => ...&& x.PositionEffect ==（byte？）positionEffect）
  

那么为什么实体框架在这里生成错误的查询，有没有办法解决这个问题？ p>

谢谢，

Tom

解决方案

如Will A指出的，这似乎是实体框架中报告的错误，生成正确查询的解决方法是：

 （positionEffect == null？x.PositionEffect == null：x.PositionEffect ==（byte？）positionEffect）
  

I have a problem querying data from a table with a nullable tinyint column.
The problem seems to be that the query is generated as:

AND ( CAST( [Extent1].[PositionEffect] AS int) = @p__linq__3)

=> @p__linq__3 = NULL

If i run that query manually it doesn't turn up any results. However, when I replace the query with:

AND ([Extent1].[PositionEffect] IS @p__linq__3)

it turns up the expected results.
My C# query looks like this:

 context.Allocations.Where(x => ... && x.PositionEffect == (byte?) positionEffect)

So, why is the entity framework generating the incorrect query here and is there any way to fix this?

Thanks,

Tom

解决方案

as Will A pointed out, this seems to be a reported bug in Entity Framework and the workaround to generate the correct query is:

 (positionEffect == null ? x.PositionEffect == null : x.PositionEffect == (byte?)positionEffect)

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