Queryable.Any（）返回null？ [英] Queryable.Any() returning null?

问题描述

我有一个数据库查询，如：

I have a database lookup like:

var configs = dbData.Configs.Where(e => headers.Contains(e.headerId) && e.flag == "true");
if(configs.Any())
{ ... }

其中，CONFIGS返回为一个IQueryable类型。我有时会收到此错误：

where configs is returned as an IQueryable type. I sometimes get this error:

System.InvalidOperationException：演员到值类型'布尔'
失败，因为物化价值空值。无论结果
型的泛型参数或查询必须使用可空类型。在在

System.Data.Common.Internal.Materialization.Shaper.ErrorHandlingValueReader 1.GetValue（DbDataReader
读卡器，有序的Int32）System.Data.Common.Internal .Materialization.Shaper.GetColumnValueWithErrorHandling在
System.Data.Common.Internal.Materialization.Coordinator [TColumn]（的Int32
序） 1.ReadNextElement（整形
成型机）在
System.Data.Common.Internal.Materialization.Shaper 1.SimpleEnumerator.MoveNext（）
在System.Linq.Enumerable.Single [TSource]（IEnumerable的 1源）b System.Linq.Queryable.Any [TSource]（IQueryable`1源）

System.InvalidOperationException: The cast to value type 'Boolean' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type. at System.Data.Common.Internal.Materialization.Shaper.ErrorHandlingValueReader1.GetValue(DbDataReader reader, Int32 ordinal) at System.Data.Common.Internal.Materialization.Shaper.GetColumnValueWithErrorHandling[TColumn](Int32 ordinal) at System.Data.Common.Internal.Materialization.Coordinator1.ReadNextElement(Shaper shaper) at System.Data.Common.Internal.Materialization.Shaper1.SimpleEnumerator.MoveNext() at System.Linq.Enumerable.Single[TSource](IEnumerable1 source) at System.Linq.Queryable.Any[TSource](IQueryable`1 source)

它发生在生产，看似随意，我一直无法重现它在发展

It happens in production, seemingly randomly and I haven't been able to reproduce it in development.

编辑补充：该配置类型都有一个外键约束，如果布尔类型正在从投，我不知道。有一个在由实体框架创建的配置类型没有布尔也没有布尔类型在SQL服务器反正。

EDIT TO ADD: The Config type has a foreign key constraint, if the Boolean type is being cast from that, I don't know. There is no Boolean in the Config type created by Entity Framework and there is no Boolean type in Sql Server anyway.

推荐答案

您有在你的Configs表中的一些数据库列有一个可空布尔类型，但你映射表项的C＃实体被定义为使用非空的布尔值。当C＃实体正在被查询提供商，填充当它运行到空值，它会抛出这个异常。您需要更新的实体对象，这样有问题的列是正确的类型。

You have some database column in your Configs table that has a nullable boolean type, but the C# entity you are mapping the table entry to is defined as using a non-nullable boolean. When the C# entity is being populated by the query provider, when it runs into a null value, it throws this exception. You need to update the entity object so that the column in question is of the proper type.

这篇关于Queryable.Any（）返回null？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！