[nhibernate-issues] [NHJIRA] Commented: (NH-2762) Failed to use IGrouping<TKey, TElement>.Contains() from Lookup to make SQL IN statement

[Mazlan (JIRA) <nh...@gm...>]

    [ http://216.121.112.228/browse/NH-2762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=21279#action_21279 ] 

Mazlan commented on NH-2762:
----------------------------

:) Emm...it not only affect v3.1 but until the nightly build release.
I create the test project which I attached above and tested from the current trunk.
It was failed at least in my last checkout reversion 5914, so the new v3.2 beta also the same.
Good luck.

> Failed to use IGrouping<TKey, TElement>.Contains() from Lookup to make SQL IN statement
> ---------------------------------------------------------------------------------------
>
>                 Key: NH-2762
>                 URL: http://216.121.112.228/browse/NH-2762
>             Project:  NHibernate
>          Issue Type: Bug
>          Components: Linq Provider
>    Affects Versions: 3.1.0
>            Reporter: Mazlan
>            Priority: Minor
>         Attachments: NH2762.zip
>
>
> This bug still happened in current Revision 5914.
> Using array, List or collection does not have a problem to make SQL IN statement by using Contains() method.
> However NHibernate does not generete SQL IN statement from IGrouping<TKey, TElement> type which is mostly used from ILookup<TKey, TElement>.
> It simply pass it to SQL parameter which then will cause GenericADOException.
> Reproduce:
>                 var Emps = (from e in s.Query<Employee>()
>                             select e).ToList();
>                 var EmpsInDept = Emps.ToLookup(e => e.Department, e => e.Id); // e.Department is a type of string.
>                 foreach (var DeptGroup in EmpsInDept)
>                 {
>                     if (DeptGroup.Key == "IT")
>                     {
>                         var firstNameInIT = (from e in s.Query<Employee>()
>                                              where DeptGroup.Contains(e.Id)
>                                              select e.FirstName).ToList();
>                     }
>                 }
> The "DeptGroup.Contains(e.Id)" will throw the exception. Currently convert it to a List temporarily fix it "DeptGroup.ToList().Contains(e.Id)".
> Note:
> IGrouping<TKey, TElement> is also IEnumerable<TElement> which can be used like this:
>                             List<string> list = new List<string>(DeptGroup);
>                             foreach (string dept in DeptGroup){}
> because DeptGroup is also implement IEnumerable<TElement> which is IEnumerable<string>
> Suggestion: to build the SQL IN statement do not only look for collection, List or Array type but also any of IEnumerable<TElement> with method Contains().

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