Order file by date with allowed extension

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I cannot combine the effects of selecting file extensions and sorting

What I have tried:

C#

//Allowed extension

var allowedExtensions = new[] { ".jpg", ".jpe", ".bmp", ".gif", ".png", ".jpeg", ".mp4", ".flv", ".wav", ".mp3" };

//read files by extension rule (where ...)
var files = Directory
            .GetFiles(path)                
            .Where(file => allowedExtensions.Any(file.ToLower().EndsWith))
            -->  .OrderBy(file => file.LastWriteTime) <-- this wrong 
            .ToList();


//example to read in date order

var sortedFiles = new DirectoryInfo(@path).GetFiles()                
                 .OrderBy(f => f.LastWriteTime)
                 .ToList();

how can I add OrderBy After Where .... ?

Posted 19-Mar-21 6:39am

Member 13174280

Updated 19-Mar-21 7:33am

PIEBALDconsult

v2

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2 solutions

Solution 2

Directory.GetFiles Method (System.IO) | Microsoft Docs[^] returns an array of Strings. And String objects do not have a LastWriteTime property.

Posted 19-Mar-21 7:08am

Richard MacCutchan

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Maciej Los 21-Mar-21 6:04am

5ed!
Short And To The Point!

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OriginalGriff · Accepted Answer · 2021-03-19T07:05:00

Solution 1

This is one of the good reasons for not using var all the time ...
Directory.GetFiles returns an array of strings, not FileInformation objects.
And strings don't have a LastWriteTime property.

Try using DirectoryInfo:

C#

DirectoryInfo directoryInfo = new DirectoryInfo(path);
var files = directoryInfo.GetFiles()
            .Where(file => allowedExtensions.Any(file.Extension.ToLower().EndsWith))
            .OrderBy(file => file.LastWriteTime)
            .ToList();

Posted 19-Mar-21 7:05am

OriginalGriff

Comments

Richard MacCutchan 19-Mar-21 13:11pm

Quote:This is one of the good reasons for not using var all the time ...Hmm!

OriginalGriff 19-Mar-21 13:27pm

If he'd used an explicit type - string[] or FileInformation[] - it would have been obvious. The first would tell him "it's a string, it doesn't have a write time", the second and the compiler would have told him "you can't cast a string[] to a FileInformation[]".

Not caring what your data type is because "the system will sort it out and it's easier to type" is a big mistake!

Richard MacCutchan 19-Mar-21 13:33pm

My comment was alluding to your use of var in your sample code. :)

OriginalGriff 19-Mar-21 13:36pm

What can I say? I copy'n'pasted without thinking ... :laugh:

Maciej Los 21-Mar-21 6:04am

You've made me sad ;(
The answer is correct even if the copy of code was made "without thinking".
5ed!

Richard Deeming 19-Mar-21 13:12pm

I'd be inclined to get rid of that .ToLower().EndsWith, and just use a HashSet<string> with a case-insensitive comparer. :)