List<Post> list =
(
from c in db.TitleComments
join t in db.Titles on c.TitleId equals t.Id
join u in db.Users on c.UserId equals u.Id
where t.Id == _titleId && c.Date > time
orderby c.Date descending
select new Post { Username = u.Username,PostingDate = c.Date.ToString(),Data = c.Comment }
).ToList();
上面的代码导致date转换为string,PostingDate = c.Date.ToString().任何想法如何解决这个问题？
异常错误：
{“LINQ to Entities无法识别方法’System.String ToString()’方法,并且此方法无法转换为商店表达式.”}
解决方法
linq试图使用sql将日期转换为字符串,但由于sql中没有ToString()方法它无法转换它,这种行为是设计的 – Joakim
换句话说,返回日期本身并在sql端执行后将其转换为字符串：
(
select new { Username = u.Username,PostingDate = c.Date
[...]
})
.ToList() // runs on sql and returns to the application
.Select(o => // is not generating a sql,it is running on the app
new Post { Username = o.Username,PostingDate = o.PostingDate.ToString(),[...]
})
