C#•2y ago

LINQ Lambda-Expression Diff

It's probably very simple, I'm just on the fence today. The Lambda version works as expected the Expression version does not. Do you see where the difference is? Works:

var groupedOccurences = occurences
                    .SelectMany(static occurence => occurence.MailAddress.Split(',', StringSplitOptions.RemoveEmptyEntries).Select(addr => new
                    {
                        MailAddress = addr.Trim(),
                        occurence.DatabasePath,
                        occurence.MaskName
                    }))
                    .GroupBy(static occurence => occurence);

var groupedOccurences = occurences
                    .SelectMany(static occurence => occurence.MailAddress.Split(',', StringSplitOptions.RemoveEmptyEntries).Select(addr => new
                    {
                        MailAddress = addr.Trim(),
                        occurence.DatabasePath,
                        occurence.MaskName
                    }))
                    .GroupBy(static occurence => occurence);

Does not work (different results):

var groupedOccurences = from occurence in occurences
                        from address in occurence.MailAddress.Split(',', StringSplitOptions.RemoveEmptyEntries)
                        group new {
                            MailAddress = address.Trim(),
                            occurence.DatabasePath,
                            occurence.MaskName
                        } by occurence into grp
                        select grp;

var groupedOccurences = from occurence in occurences
                        from address in occurence.MailAddress.Split(',', StringSplitOptions.RemoveEmptyEntries)
                        group new {
                            MailAddress = address.Trim(),
                            occurence.DatabasePath,
                            occurence.MaskName
                        } by occurence into grp
                        select grp;

3 Replies

ero•2y ago

Why would you use the query expression in the first place...? Well anyway Doesn't your IDE offer to convert the call chain to a query expression on Ctrl + .?

Robin Lindner•2y ago

readability? why wouldn't you use it? nope

ero•2y ago

May god have mercy on your soul if you think that's more readable

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LINQ Lambda-Expression Diff