How to sort Generic List Asc or Desc?


Question

I have a generic collection of type MyImageClass, and MyImageClass has an boolean property "IsProfile". I want to sort this generic list which IsProfile == true stands at the start of the list.

I have tried this.

rptBigImages.DataSource = estate.Images.OrderBy(est=>est.IsProfile).ToList();

with the code above the image stands at the last which IsProfile property is true. But i want it to be at the first index. I need something Asc or Desc. Then i did this.

rptBigImages.DataSource = estate.Images.OrderBy(est=>est.IsProfile).Reverse.ToList();

Is there any easier way to do this ?

Thanks

2
21
2/10/2009 11:55:56 AM

Accepted Answer

How about:

estate.Images.OrderByDescending(est => est.IsProfile).ToList()

This will order the Images in descending order by the IsProfile Property and then create a new List from the result.

39
2/10/2009 12:01:02 PM

Exper Answer

You can use .OrderByDescending(...) - but note that with the LINQ methods you are creating a new ordered list, not ordering the existing list.

If you have a List<T> and want to re-order the existing list, then you can use Sort() - and you can make it easier by adding a few extension methods:

static void Sort<TSource, TValue>(this List<TSource> source,
        Func<TSource, TValue> selector) {
    var comparer = Comparer<TValue>.Default;
    source.Sort((x,y)=>comparer.Compare(selector(x),selector(y)));
}
static void SortDescending<TSource, TValue>(this List<TSource> source,
        Func<TSource, TValue> selector) {
    var comparer = Comparer<TValue>.Default;
    source.Sort((x,y)=>comparer.Compare(selector(y),selector(x)));
}

Then you can use list.Sort(x=>x.SomeProperty) and list.SortDescending(x=>x.SomeProperty).

33
2/10/2009 11:58:52 AM

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