LINQ string contains another string case insensitive

Question

I'm working in a C# Windows 8 Metro app and I'm trying to filter an ObservableCollection<T> using LINQ where a property contains some string, and I need that it will be case insensitive.

 var searchResults = from _rest in App.ViewModel.Restaurants
                     where  _rest.Name.IndexOf(queryText,
                                 StringComparison.CurrentCultureIgnoreCase) >= 0
                     select _rest;

I work around

Using string1.Contains(string2).ToUpper() in both strings.
Using string1.Contains(string2).ToLower() in both strings.
Using string1.IndexOf(string2, StringComparison.CurrentCultureIgnoreCase) >= 0.
Using string1.IndexOf(string2, StringComparison.OrdinalIgnoreCase) >= 0.
Using String.Compare(string1, string2, StringComparison.CurrentCultureIgnoreCase).

But no one of this methods works for me in a case insensitive way, works ok if I write the name correctly.

Has someone have the same issue in Windows 8??

Thanks in advance for any help provided.

Can you give a short but complete example demonstrating the problem? — Jon Skeet, Jun 20 '12 at 12:39
They aren't Continental European restaurant names are they? ;-) — dash, Jun 20 '12 at 12:58
Does it work as you want it to if you apply the same LINQ expression in for example a .NET 4(.0) WPF application? — Anders Gustafsson, Jun 20 '12 at 13:19
Made a simple .NET 4.5 Metro application (VS 2011 Beta, En-US culture) and applied your LINQ expression. Works as expected. Which culture are you using? — Anders Gustafsson, Jun 20 '12 at 15:01
What kind of example did you mean?? I'm loading the ObservableCollection deserializating an UTF-8 XML document, I have no issues here and the collection is populated fine. For example I have around 30 restaurants that contains "Despensa" in their names, if I search the word "Despensa", my app shows this 30 results, but if I search "despensa", "DESPENSA", or "DesPensA" the app shows me no results. I'll try to make a new empty Metro app this morning. — Rotten, Jun 21 '12 at 06:42

score 1 · Answer 1 · answered Oct 17 '12 at 15:19

Write you own Extension Method

public static class MetroHelper
{
    public static bool ContainsInvariant(this string mainText, string queryText)
    {
        return mainText.ToUpperInvariant().Contains(queryText.ToUpperInvariant());
    }
}

and use in your application

var searchResults = from _rest in App.ViewModel.Restaurants
                 where  _rest.Name.ContainsInvariant(queryText)
                 select _rest;

That's what I did.

score 0 · Answer 2 · answered Jun 21 '12 at 13:06

0

try this:

var searchResults = from _rest in App.ViewModel.Restaurants
                         where  _rest.Name.IndexOf(queryText,
                                     StringComparison.InvariantCultureIgnoreCase) >= 0
                         select _rest;

answered Jun 21 '12 at 13:06

Dean Chalk

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StringComparison.InvariantCultureIgnoreCase is not available in Metro Apps. – Rotten Jun 21 '12 at 14:06

LINQ string contains another string case insensitive

2 Answers2