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

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

Failed to use IGrouping<TKey, TElement>.Contains() from Lookup to make SQL IN statement
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                 Key: NH-2762
                 URL: http://216.121.112.228/browse/NH-2762
             Project:  NHibernate
          Issue Type: Bug
          Components: Linq Provider
    Affects Versions: 3.2.0Beta1, 3.2.0Alpha3, 3.2.0Alpha2, 3.2.0Alpha1, 3.1.0, 3.0.0.GA, 3.0.0.CR1, 3.0.0.Beta2, 3.0.0.Beta1, 3.0.0.Alpha3, 3.0.0.Alpha2, 3.0.0.Alpha1, 2.1.2.GA, 2.1.1.GA,  2.0.1.GA, 1.2.1, 3.2.0Beta2
            Reporter: Mazlan
            Priority: Minor


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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