Sequence contains no elements?

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I'm currently using a single query in two places to get a row from a database.

BlogPost post = (from p in dc.BlogPosts
                 where p.BlogPostID == ID
                 select p).Single();

The query is fine when retrieving the row to put data in to the text boxes, but it returns an error "Sequence contains no elements" when used to retrieve the row in order to edit it and put it back in to the database. I can't understand why it might find an appropriate row in one instance but not another.

(Using ASP.NET MVC and LINQ)

linq c#
8 Answers

In addition to everything else that has been said, you can call DefaultIfEmpty() before you call Single(). This will ensure that your sequence contains something and thereby averts the InvalidOperationException "Sequence contains no elements". For example:

BlogPost post = (from p in dc.BlogPosts
                 where p.BlogPostID == ID
                 select p).DefaultIfEmpty().Single();
user_48796220

I had a similar situation on a function that calculates the average.

Example: 

ws.Cells[lastRow, startingmonths].Value = lstMediaValues.Average();

Case Solved: 

ws.Cells[lastRow, startingmonths].Value = lstMediaValues.Count == 0 ? 0 : lstMediaValues.Average();
user_105910450

please check your connection string, maybe it wrong. It was my case.

user_138954830
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