C# Linq SelectMany, returning entire object

Question

I have a class like this:

public class FileCollection:ObservableCollection<IUserFile>.

From within the class, I would like to get a subset of the collection, based on a list of names.

I imagine it would be something like this:

List<IUserFile> selectedFiles = new List<IUserFile>;
foreach(string s in names)  
{  
    var matchingFiles = this.SelectMany(userFile => userFile.Name.Equals(s));  
    foreach(IUserFile uf in matchingFiles)  
    {  
        selectedFiles.Add(uf);    
    }  
 }

At this point, I'm having trouble with the Select or SelectMany call; the compiler error messages are not that helpful.
Any suggestions on how to extract the subset from the collection would be appreciated...

Although I know it might look like `SelectMany` should "select many" of the source, actually what you want is `Where`. `SelectMany` is for when for each item in the source you want to select many *other* things (eg from a list of parents, you might `SelectMany` to produce a list of children). — AakashM, Mar 12 '13 at 16:11

score 3 · Accepted Answer · answered Mar 12 '13 at 15:57

3

Use a Where instead - which "Filters a sequence of values based on a predicate" - such that:

var matches = this.Where(userFile => userFile.Name.Equals(s));

Rather than SelectMany, which "Projects each element of a sequence to an IEnumerable and flattens the resulting sequences into one sequence."

answered Mar 12 '13 at 15:57

Grant Thomas

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Thanks for the reply. I just discovered that this.Where() is exactly what I'm looking for. – Number8 Mar 12 '13 at 16:13

C# Linq SelectMany, returning entire object

1 Answers1