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Linq Distinct Troubles

Posted on 2010-11-19
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Last Modified: 2013-11-11
I am tiring to select distinct values by a object property.  What am I doing wrong?  I am getting the errors:


Error      14      'System.Linq.IOrderedEnumerable<MB.Core.Record>' does not contain a definition for 'Distinct' and the best extension method overload 'System.Linq.ParallelEnumerable.Distinct<TSource>(System.Linq.ParallelQuery<TSource>, System.Collections.Generic.IEqualityComparer<TSource>)' has some invalid arguments      

and

Error      15      Instance argument: cannot convert from 'System.Linq.IOrderedEnumerable<MB.Core.Record>' to 'System.Linq.ParallelQuery<MB.Core.RecordLesson>'

Code Posted Below.

Thanks!

List<Record> allStudentRecords = RecordBuilder.GetAllRecordsByStudentId(CurrentStudent.StudentId).OrderByDescending(r => r.RecordLevel).Distinct(new DistinctLesson()).ToList<Record>();


    public class DistinctLesson : IEqualityComparer<RecordLesson>
    {
        public bool Equals(RecordLesson x, RecordLesson y)
        {
            return x.RecordLessonName.Equals(y.RecordLessonName);
        }

        public int GetHashCode(RecordLesson obj)
        {
            return obj.RecordLessonName.GetHashCode();
        }
    }

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Question by:grogo212
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2 Comments
 
LVL 23

Accepted Solution

by:
Snarf0001 earned 500 total points
ID: 34176866
What type does RecordBuilder.GetAllRecordsByStudentId return?

It appears from the code that it returns a Record object, but you're trying to pass it to an equality comparer that expects a RecordLesson object.
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Author Comment

by:grogo212
ID: 34176896
Your Right! Silly mistake

Here's my modified code:
public class DistinctLesson : IEqualityComparer<Record>
    {
        public bool Equals(Record x, Record y)
        {
            return x.RecordLesson.RecordLessonName.Equals(y.RecordLesson.RecordLessonName);
        }

        public int GetHashCode(Record obj)
        {
            return obj.RecordLesson.RecordLessonName.GetHashCode();
        }
    }

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