LINQ how do I get filename containing specific value

Question

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I have a program that should return only one filename, and this is based on whether the name of the file contains a certain string. I am able to enumerate files from the directory but i am getting

System.Linq.Enumerable+WhereSelectEnumerableIterat
for the select instead of the actual filename. In the folder i have files named :

GL_Export_54_201908220333.xml
GL_Export_55_201907081053.xml
GL_Export_56_201908220337.xml
GL_Export_78_201907081055.xml

Code :

C#

<pre>string period = "55";
 var batchperiod = period.ToString();
 string BatchInPath = @"C:\Users\myuser\source\repos\MySolution\MyProject\BatchIn";
 IEnumerable<string> fileList = Directory.EnumerateFiles( BatchInPath);
  var CurrentBatchName = from file in fileList
                         let fileName = Path.GetFileName(file)
                         where fileName.Contains(batchperiod)
                         select fileName.ToString().First();            
Console.WriteLine(CurrentBatchName)

So with batchperiod as above:

EXPECTED OUTPUT

C#

GL_Export_55_201907081053.xml

ACTUAL OUTPUT

C#

System.Linq.Enumerable+WhereSelectEnumerableIterat

What I have tried:

C#

<pre> string period = "55";
 var batchperiod = period.ToString();
 string BatchInPath = @"C:\Users\myuser\source\repos\MySolution\MyProject\BatchIn";
 IEnumerable<string> fileList = Directory.EnumerateFiles( BatchInPath);
  var CurrentBatchName = from file in fileList
                         let fileName = Path.GetFileName(file)
                         where fileName.Contains(batchperiod)
                         select fileName.SingleOrDefault();            
Console.WriteLine(CurrentBatchName)

Posted 10-Jan-20 0:02am

Tshumore

Updated 10-Jan-20 0:33am

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Comments

Maciej Los 10-Jan-20 7:50am

Your requirement is not clear. Please, read all answers to find out why, especially the answer provided by @phil.o.

3 solutions

Solution 1

C#

string period = "55";
var batchperiod = period.ToString();

Why are you doing this? Calling ToString() on a variable which already is a string just does not make any sense.
Moreover, Enumerable.SingleOrDefault Method[^] throws an exception if there is more than one element in the sequence. Which is the case here, since these lines:

GL_Export_55_201907081053.xml
GL_Export_78_201907081055.xml

both contains the 55 character sequence.
Maybe you need a regular expression to filter the result more acurately?

Posted 10-Jan-20 0:22am

phil.o

Comments

Maciej Los 10-Jan-20 7:47am

Good catch!

phil.o 10-Jan-20 8:12am

Thanks Maciej :)

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F-ES Sitecore · Accepted Answer · 2020-01-10T00:32:00

Solution 2

Just do something simple like

var CurrentBatchName = fileList.FirstOrDefault(f => f.Contains(batchperiod));

Posted 10-Jan-20 0:32am

F-ES Sitecore

Comments

Maciej Los 10-Jan-20 7:47am

5!

OriginalGriff · Accepted Answer · 2020-01-10T00:33:00

Solution 3

Try:

C#

string batchperiod = "_55_";
string BatchInPath = @"C:\Users\myuser\source\repos\MySolution\MyProject\BatchIn";
IEnumerable<string> fileList = Directory.EnumerateFiles(BatchInPath);
var CurrentBatchName = (from file in fileList
                       let fileName = Path.GetFileName(file)
                       where fileName.Contains(batchperiod)
                       select fileName).FirstOrDefault();
Console.WriteLine(CurrentBatchName);

Posted 10-Jan-20 0:33am

OriginalGriff

Comments

Maciej Los 10-Jan-20 7:49am

This is correct while OP wants to get only first "instance" of 55 ;)

phil.o 10-Jan-20 8:13am

Adding prefix and suffix underscore is enough to discriminate in this case.