Created
March 13, 2013 07:14
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@vwxyzh EF里遇到一个诡异的问题：某表增加了一个字段A(类型为short?)，更新了Entity, 程序中第一次使用该Entity的地方，是IQueryable<entity>.Min(r => r.B)，当程序连接到另一台未添加字段的数据库，运行时并没有认为表结构有差异，而是返回这么一个异常:
Min "The cast to value type 'Int16' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type."
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| // 修改前报异常。Entity中缺少新增的字段A，但是返回的异常是一个类型转换相关的 | |
| short minSecId = queryNoCached.Min(prc => prc.CacheHour); | |
| // 修改后, 运行时容忍了Entity中缺少了新增的字段 | |
| short minSecId = queryNoCached.Min(prc => (short?)prc.CacheHour) ?? 0; |
we do have a universal solution to these kind of problems:
step 1. restart your ide, if no effect go to step 2
step 2. restart your pc, if no effect go to step 3
step 3. try carefully re-install your ide, if no effect go to step 4
step 4. try re-install your os, if no effect go to step 5
step 5. redo from step 1 more carefully.
LSS的回答太搞笑了。。。
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呃。。。