LINQ Queries with dynamic Order By - more than one field

Question

I have a collection with name,date,category as parameters. I want to sort the list based on the input order of the three which changes dynamically. For ex: in one case i have to sort on the order date,name, category respectively. in another case the order is name, date and category.So i can have all the permutation and combinations. Can someone help me with a generic way to implement it.

possible duplicate of [Multiple "order by" in LINQ](http://stackoverflow.com/questions/298725/multiple-order-by-in-linq) — Panagiotis Kanavos, Sep 24 '13 at 06:46
http://stackoverflow.com/questions/41244/dynamic-linq-orderby-on-ienumerablet — JohnLBevan, Sep 24 '13 at 06:48
LINQ provides this out of the box using the ThenBy function, no need to use Dynamic Linq or anything — Panagiotis Kanavos, Sep 24 '13 at 06:50
i know that LinQ has orderby and thenby function. But the problem here is since the order of fields is dynamic, how do i pass the field and arrange them accordingly ? — user1687824, Sep 24 '13 at 07:06

score 1 · Answer 1 · edited May 23 '17 at 10:31

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LINQ already allows you to sort using multiple fields by adding the Queryable.ThenBy, QueryableThenByDescending, Enumerable.ThenBy or Enumerable.ThenByDescending functions after OrderBy.

Check Multiple “order by” in LINQ for a similar question and the discussion.

As an aside, you can convert an Enumerable to a Queryable simply calling AsQueryable on it, if you need a rare method that is not provided by Enumerable.

edited May 23 '17 at 10:31

Community

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answered Sep 24 '13 at 06:49

Panagiotis Kanavos

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i know that LinQ has orderby and thenby function. But the problem here is since the order of fields is dynamic, how do i pass the field and arrange them accordingly ? – user1687824 Sep 24 '13 at 07:21
You don't need to *pass* anything, just call ThenBy with the appropriate lambda depending on the field you want to order by. Even a simple switch statement is OK. Or, you can create an array/list with the lambdas you want to order by and apply them one by one. A lambda is just another type of variable after all – Panagiotis Kanavos Sep 24 '13 at 07:25
i am not sure if you ve understood me rightly or i did not get it ...can you gimme the sample code ? According to yoursolution for the first field i need to give orderby. and for the rest its thenby? so how do make it possible dynamically ? – user1687824 Sep 24 '13 at 08:40

score 0 · Answer 2 · answered Sep 24 '13 at 06:45

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I also found here something that he might like: http://www.codeproject.com/Articles/27834/Generic-List-Sort-Function <-- hope it helps, it sorts by any input property. The property is taken through reflection.

answered Sep 24 '13 at 06:45

Andrei Neculai

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the method is implemented in List and not IQueryable. So can only be used after a .ToList() or in other words after the data has been loaded. – Parv Sharma Sep 24 '13 at 06:48

score 0 · Answer 3 · answered Sep 24 '13 at 06:52

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Here is an example

// Just to get IOrderedEnumerable from the collection
// And set the default order
var orderedItems = context.Items.OrderBy(i => i.Name);

var orderByString = txtOrderBy.Text.ToLower();
switch(orderByString)
{
    case "category":
        orderedItems = orderedItems.OrderBy(i => i.Category);
        break;
    case "date":
        orderedItems = orderedItems.OrderBy(i => i.Date);
        break;
    default:
        break;
}

answered Sep 24 '13 at 06:52

Ahmed Magdy

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This does NOT order by a set of fields, only the last OrderBy field counts. – Panagiotis Kanavos Sep 24 '13 at 06:56

LINQ Queries with dynamic Order By - more than one field

3 Answers3