CODEWITHSUNDEEP
c#.netlinqlistfiltering
Mark Johnson
Mark Johnson

Reputation: 445

Linq filter List<string> where it contains a string value from another List<string>

I have 2 List objects (simplified):

var fileList = Directory.EnumerateFiles(baseSourceFolderStr, fileNameStartStr + "*", SearchOption.AllDirectories);

var filterList = new List<string>();
filterList.Add("ThisFolderName");
filterList.Add("ThatFolderName");

I want to filter the fileLst to return only files containing any of folder names from the filterList. (I hope that makes sense..)

I have tried the following expression, but this always returns an empty list.

var filteredFileList = fileList.Where(fl => fl.Any(x => filterList.Contains(x.ToString())));

I can't seem to make sense of why I am getting nothing, clearly I am missing something, but I have no idea what.

[EDIT]

Ok, so it appears I should have been clearer in my question, I was trying to search for files in my fileList with a substring containing string values from my filterList. I have marked the answer below for those who are trying to do a similar thing.

Upvotes: 39

Views: 157843

Answers (4)

abdulkareem amoora
abdulkareem amoora

Reputation: 15

Select * from employee Where cityID in ( select cityID from cities where countryID=1)

Upvotes: 0

fixagon
fixagon

Reputation: 5566

its even easier:

fileList.Where(item => filterList.Contains(item))

in case you want to filter not for an exact match but for a "contains" you can use this expression:

var t = fileList.Where(file => filterList.Any(folder => file.ToUpperInvariant().Contains(folder.ToUpperInvariant())));

Upvotes: 74

Jamie Keeling
Jamie Keeling

Reputation: 9966

Try the following:

var filteredFileSet = fileList.Where(item => filterList.Contains(item));

When you iterate over filteredFileSet (See LINQ Execution) it will consist of a set of IEnumberable values. This is based on the Where Operator checking to ensure that items within the fileList data set are contained within the filterList set.

As fileList is an IEnumerable set of string values, you can pass the 'item' value directly into the Contains method.

Upvotes: 10

Akrem
Akrem

Reputation: 4652

you can do that 

var filteredFileList = fileList.Where(fl => filterList.Contains(fl.ToString()));

Upvotes: 1

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