c# - .Any 导致转换为值类型 'Boolean' 失败，因为物化值为 null

Question

完整的错误信息:

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.

代码:

 var messages = ctx.tblMessageQueue.Where(o => o.Status == status && o.Region == region);     
 //o.Status is a byte type and not nullable, o.Region is an int type and not nullable.

 if(messages != null && messages.Any()) => Triggers the Error
 {...
 }

堆栈跟踪是:

at System.Data.Common.Internal.Materialization.Shaper.ErrorHandlingValueReader1.GetValue(DbDataReader reader, Int32 ordinal) at lambda_method(Closure , Shaper ) 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.Data.Objects.ELinq.ObjectQueryProvider.b__3[TResult](IEnumerable1 sequence) at System.Data.Objects.ELinq.ObjectQueryProvider.ExecuteSingle[TResult](IEnumerable1 query, Expression queryRoot) at at System.Linq.Queryable.Any[TSource](IQueryable`1 source)

Answer 1

也许您的 tblMessageQueue 表中的列值之一是 NULL，而它在实体类中的对应属性是 bool 类型。如果是这样的话，这里有两个我能想到的建议:

1. 更正数据和表格，使其不包含或不允许 NULL
2. 将实体类属性更新为可为空:bool?