Linq to SQL, exception : for method string.contains, only parameters that can be evaluated on the client are supported

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C#

Linq2Sql

hi all:

I met a question that lets me to be disturbed today, although it can not produce by changing code line position, i want to know why it happens.


Steps:
1. I used Linq to get data from database, example code:

Quote:

var ret = (from c in getComment
join cr in context.GetTable<commentreply>() on c.ID equals cr.CommentID into crs
join oc in context.GetTable<ownercomment>() on c.ID equals oc.CommentID into ocs
from cr1 in crs.DefaultIfEmpty()
where c.EnumDataEntityStatus == EnumDataEntityStatus.Normal || IsForUserInfoSearch
from oc1 in ocs.DefaultIfEmpty()
where c.EnumDataEntityStatus == EnumDataEntityStatus.Normal || IsForUserInfoSearch
select new CommentSearchModel { comment = c, reply = cr1, ownerComment = oc1 });

2. there are two lines code, A and B, and , there are many "Linq where Sentence " lines code in front of A and B.

A is

ret = ret.Where(P => P.comment.OrderNumber.Contains(req.OrderNumber.Trim()));

B is

var excludeIDList = ret.Where(q => ((now - q.comment.CheckOutDate.Date).TotalDays > 30 && q.comment.EnumCommentStatus == 0 && q.comment.EnumOwnerCommentedStatus == 0) || q.comment.EnumCommentStatus == EnumCommentStatus.Expired).Select(x => x.comment.ID);

if (req.SpecificCondition == EnumSpecificQueryCondition.AllForMerchant)
    ret = ret.Where(q => !excludeIDList .Contains(q.comment.ID));

B is executed,then will product a new object "

{System.Data.Linq.DataQuery<TuJia.Business.Customer.Contract.CommentSearchModel>}

" .

3. question:

If A is in the front B, as execute ret.toList(), exception will be produced.
If B is in the front A, as execute ret.toList(), exception will be produced.
4. Exception:
because, i use Chinese Operation System, my exceptions are Chinese, i will translate them into English, but perhaps be incorrect.

Exception:

Quote:

For method String.Contains, only parameters that can be evaluated on the client are supported

Chinese:

内容：对于方法 String.Contains，只支持可在客户端上求值的参数

5. At last, i hope that everybody can provide me with any information about it, i want to know the reason that produce exception.

Quote:

Thanks in advance!

What I have tried:

<pre lang="c#">