Creating Key/Value collections using LINQ To Objects

collections, linq, linq-to-objects

Solution

`ToDictionary()` would have to have a special case for KeyValuePair - which you could add as your own extension method of course:

public static Dictionary<TKey, TValue> ToDictionary<TKey, TValue>(
     IEnumerable<KeyValuePair<TKey, TValue>> source)
{
    return source.ToDictionary(kvp => kvp.Key, kvp=> kvp.Value);
}

Without that extension method, you could do it like this:

var result = from f in delimFileNames.Split(Constants.DDS_FILENAME_SEPARATOR)
                                     .ToDictionary(f => f,
          // Outdented to avoid scrolling
          f => File.ReadAllBytes(Path.Combine(ddsClient.WorkingDirectory, f));

Basically the query expression allows you to do all the funky "let" stuff, but forces you to have a `select` at the end, which makes you propagate the two different values (the key and the byte array) into two properties.

Problem

I'm trying to use LINQ To Objects to create a query that will give me files, indexed by filename with a value mapping to their binary data as `byte[]`. However I can't find a 'neat' way to do this. I'm hoping to get something like a `Dictionary<T,K>` output. Here's what I have so far. Example delimFileNames="1.jpg|2.jpg" ``` //Extract filenames from filename string //and read file binary from file //select result into a filename indexed collection var result = from f in delimFileNames.Split(Constants.DDS_FILENAME_SEPARATOR) let filePath = Path.Combine(ddsClient.WorkingDirectory, f) let fileData = File.ReadAllBytes(filePath) select new KeyValuePair<string, byte[]>(f, fileData); return result.ToDictionary(kvp => kvp.Key, kvp=> kvp.Value); ``` The main head scratcher is why I can't use a parameterless ToDictionary(), or a direct cast. Any suggestions or alternatives to improve the above are appreciated.

Original source