指定的强制转换无效 [英] Specified cast is not valid exception

问题描述

大家好，
我正在使用LINQ查询从EventType表中检查ID(eventTypeID).
这是我编写的查询，在调试时它将在此行中引发异常，因为指定的强制转换无效".

 EventType事件= db.EventType.单个(f = >  f .eventTypeID == eventTypeID); 

有谁知道为什么会这样吗?

问候
Madhu

解决方案

Madhu，

请尝试一下

EventType events = (from f in db.EventType where f.eventTypeID == eventTypeID select f).Single();

尝试使用以下(SingleOrDefault()方法而不是Single()方法):

EventType events = db.EventType.SingleOrDefault(f => f.eventTypeID == eventTypeID);

尝试一下:

 EventType事件=(EventType)(db.EventType.SingleOrDefault(f = >  f.eventTypeID == eventTypeID));  pre> 


 

Hi All,
I am using LINQ query to check ID(eventTypeID) from EventType table.
This is the query which I have written,while debugging it will throw the exception in this line,as ''specified cast is not valid''.

EventType events = db.EventType.Single(f => f.eventTypeID == eventTypeID);

Does any one know why it is so??

Regards
Madhu

解决方案

Hi Madhu,

Please Try This

EventType events = (from f in db.EventType where f.eventTypeID == eventTypeID select f).Single();

Try using the following (SingleOrDefault() method instead of Single() method):

EventType events = db.EventType.SingleOrDefault(f => f.eventTypeID == eventTypeID);

Try this:

EventType events = (EventType)(db.EventType.SingleOrDefault(f => f.eventTypeID == eventTypeID));

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