Question

As an example of what I’m trying to accomplish, here is some code which builds out a list of books with a string property called Sentence.

public class Book {
    public string Sentence { get; set; }
}

Book book1 = new Book() { Sentence = "The quick brown fox jumps over the lazy dog" };
Book book2 = new Book() { Sentence = "The quick brown frog jumps over the lazy sloth" };

List<Book> books = new List<Book>();

books.Add(book1);
books.Add(book2);

I want to search through the list of books based on some user input (the search requirements shouldn’t get more complicated than this example).

If a user provides a search phrase of quick fox "lazy dog", then I went to return a List which has book1 as a member of the collection. If a user provides a search phrase of quick fox sloth nothing should be returned because those three words do not all appear in any of the properties.

Summary

1. quick fox "lazy dog" – 1 Result (the words in quotes appear together, and the remaining words appear individually)

2. quick fox sloth – No results

3. "lazy sloth" – 1 Result (both words appear together in the string)

4. lazy sloth – 1 Result (both words appear individuals in the string)

The code that I currently have:

//Turn the search word into an array of words (includes support for quotes phrases).  E.g: quick fox "lazy dog" becomes a list of these values: `quick`, `fox`, `lazy dog`.
var searchWords = Regex.Matches(searchWord, @"(?<match>\w+)|\""(?<match>[\w\s]*)""")
                       .Cast<Match>()
                       .Select(m => m.Groups["match"].Value)
                       .ToList();

var query = from b in books
            where (!string.IsNullOrEmpty(b.Sentence) && searchWords.Any(b.Sentence.Contains))
            select b;

This doesn’t work for case 2. The code I have now is just looking for 1 match, and if it gets 1 match then it considers the item found.

Answer 1

I think you might want the All() LINQ method, try this:

var query = from b in books
            where (!string.IsNullOrEmpty(b.Sentence) && searchWords.All(word => b.Sentence.Contains(word)))
            select b;