[c#] Dynamic LINQ OrderBy on IEnumerable<T> / IQueryable<T>

I found an example in the VS2008 Examples for Dynamic LINQ that allows you to use a sql-like string (e.g. OrderBy("Name, Age DESC")) for ordering. Unfortunately, the method included only works on IQueryable<T>. Is there any way to get this functionality on IEnumerable<T>?

Just stumbled across this question.

Using Marc's ApplyOrder implementation from above, I slapped together an Extension method that handles SQL-like strings like:

list.OrderBy("MyProperty DESC, MyOtherProperty ASC");

Details can be found here: http://aonnull.blogspot.com/2010/08/dynamic-sql-like-linq-orderby-extension.html

You could add it:

public static IEnumerable<T> OrderBy( this IEnumerable<T> input, string queryString) {
    //parse the string into property names
    //Use reflection to get and sort by properties
    //something like

    foreach( string propname in queryString.Split(','))
        input.OrderBy( x => GetPropertyValue( x, propname ) );

    // I used Kjetil Watnedal's reflection example
}

The GetPropertyValue function is from Kjetil Watnedal's answer

The issue would be why? Any such sort would throw exceptions at run-time, rather than compile time (like D2VIANT's answer).

If you're dealing with Linq to Sql and the orderby is an expression tree it will be converted into SQL for execution anyway.

Here's something else I found interesting. If your source is a DataTable, you can use dynamic sorting without using Dynamic Linq

DataTable orders = dataSet.Tables["SalesOrderHeader"];
EnumerableRowCollection<DataRow> query = from order in orders.AsEnumerable()
                                         orderby order.Field<DateTime>("OrderDate")
                                         select order;
DataView view = query.AsDataView();
bindingSource1.DataSource = view;

reference: http://msdn.microsoft.com/en-us/library/bb669083.aspx (Using DataSetExtensions)

Here is one more way to do it by converting it to a DataView:

DataTable contacts = dataSet.Tables["Contact"];    
DataView view = contacts.AsDataView();    
view.Sort = "LastName desc, FirstName asc";    
bindingSource1.DataSource = view;
dataGridView1.AutoResizeColumns();

You can convert the IEnumerable to IQueryable.

items = items.AsQueryable().OrderBy("Name ASC");

I was trying to do this but having problems with Kjetil Watnedal's solution because I don't use the inline linq syntax - I prefer method-style syntax. My specific problem was in trying to do dynamic sorting using a custom IComparer.

My solution ended up like this:

Given an IQueryable query like so:

List<DATA__Security__Team> teams = TeamManager.GetTeams();
var query = teams.Where(team => team.ID < 10).AsQueryable();

And given a run-time sort field argument:

string SortField; // Set at run-time to "Name"

The dynamic OrderBy looks like so:

query = query.OrderBy(item => item.GetReflectedPropertyValue(SortField));

And that's using a little helper method called GetReflectedPropertyValue():

public static string GetReflectedPropertyValue(this object subject, string field)
{
    object reflectedValue = subject.GetType().GetProperty(field).GetValue(subject, null);
    return reflectedValue != null ? reflectedValue.ToString() : "";
}

One last thing - I mentioned that I wanted the OrderBy to use custom IComparer - because I wanted to do Natural sorting.

To do that, I just alter the OrderBy to:

query = query.OrderBy(item => item.GetReflectedPropertyValue(SortField), new NaturalSortComparer<string>());

See this post for the code for NaturalSortComparer().

This answer is a response to the comments that need an example for the solution provided by @John Sheehan - Runscope

Please provide an example for the rest of us.

in DAL (Data Access Layer),

The IEnumerable version:

  public  IEnumerable<Order> GetOrders()
    {
      // i use Dapper to return IEnumerable<T> using Query<T>
      //.. do stuff
      return  orders  // IEnumerable<Order>
  }

The IQueryable version

  public IQueryable<Order> GetOrdersAsQuerable()
    {
        IEnumerable<Order> qry= GetOrders();
        //use the built-in extension method  AsQueryable in  System.Linq namespace
        return qry.AsQueryable();            
    }

Now you can use the IQueryable version to bind, for example GridView in Asp.net and benefit for sorting (you can't sort using IEnumerable version)

I used Dapper as ORM and build IQueryable version and utilized sorting in GridView in asp.net so easy.

Too easy without any complication:

1. Add using System.Linq.Dynamic; at the top.
2. Use vehicles = vehicles.AsQueryable().OrderBy("Make ASC, Year DESC").ToList();

An alternate solution uses the following class/interface. It's not truly dynamic, but it works.

public interface IID
{
    int ID
    {
        get; set;
    }
}

public static class Utils
{
    public static int GetID<T>(ObjectQuery<T> items) where T:EntityObject, IID
    {
        if (items.Count() == 0) return 1;
        return items.OrderByDescending(u => u.ID).FirstOrDefault().ID + 1;
    }
}

Just building on what others have said. I found that the following works quite well.

public static IEnumerable<T> OrderBy<T>(this IEnumerable<T> input, string queryString)
{
    if (string.IsNullOrEmpty(queryString))
        return input;

    int i = 0;
    foreach (string propname in queryString.Split(','))
    {
        var subContent = propname.Split('|');
        if (Convert.ToInt32(subContent[1].Trim()) == 0)
        {
            if (i == 0)
                input = input.OrderBy(x => GetPropertyValue(x, subContent[0].Trim()));
            else
                input = ((IOrderedEnumerable<T>)input).ThenBy(x => GetPropertyValue(x, subContent[0].Trim()));
        }
        else
        {
            if (i == 0)
                input = input.OrderByDescending(x => GetPropertyValue(x, subContent[0].Trim()));
            else
                input = ((IOrderedEnumerable<T>)input).ThenByDescending(x => GetPropertyValue(x, subContent[0].Trim()));
        }
        i++;
    }

    return input;
}

I've stumble this question looking for Linq multiple orderby clauses and maybe this was what the author was looking for

Here's how to do that:

var query = pets.OrderBy(pet => pet.Name).ThenByDescending(pet => pet.Age);    

you can do it like this for multiple order by

IOrderedEnumerable<JToken> sort;
                        if (query.OrderBys[0].IsDESC)
                        {
                            sort = jarry.OrderByDescending(r => (string)r[query.OrderBys[0].Key]);
                        }
                        else
                        {
                            sort = jarry.OrderBy(r =>
                                (string) r[query.OrderBys[0].Key]); 
                        }
                        foreach (var item in query.OrderBys.Skip(1))
                        {
                            if (item.IsDESC)
                            {
                                sort = sort.ThenByDescending(r => (string)r[item.Key]);
                            }
                            else
                            {
                                sort = sort.ThenBy(r => (string)r[item.Key]);
                            }
                        }

Convert List to IEnumerable or Iquerable, add using System.LINQ.Dynamic namespace, then u can mention the property names in comma seperated string to OrderBy Method which comes by default from System.LINQ.Dynamic.

Use dynamic linq

just add using System.Linq.Dynamic;

And use it like this to order all your columns:

string sortTypeStr = "ASC"; // or DESC
string SortColumnName = "Age"; // Your column name
query = query.OrderBy($"{SortColumnName} {sortTypeStr}");

var result1 = lst.OrderBy(a=>a.Name);// for ascending order. 
 var result1 = lst.OrderByDescending(a=>a.Name);// for desc order. 

I guess it would work to use reflection to get whatever property you want to sort on:

IEnumerable<T> myEnumerables
var query=from enumerable in myenumerables
          where some criteria
          orderby GetPropertyValue(enumerable,"SomeProperty")
          select enumerable

private static object GetPropertyValue(object obj, string property)
{
    System.Reflection.PropertyInfo propertyInfo=obj.GetType().GetProperty(property);
    return propertyInfo.GetValue(obj, null);
}

Note that using reflection is considerably slower than accessing the property directly, so the performance would have to be investigated.

You can use this:

        public List<Book> Books(string orderField, bool desc, int skip, int take)
{
    var propertyInfo = typeof(Book).GetProperty(orderField);

    return _context.Books
        .Where(...)
        .OrderBy(p => !desc ? propertyInfo.GetValue(p, null) : 0)
        .ThenByDescending(p => desc ? propertyInfo.GetValue(p, null) : 0)
        .Skip(skip)
        .Take(take)
        .ToList();
}

After a lot of searching this worked for me:

public static IEnumerable<TEntity> OrderBy<TEntity>(this IEnumerable<TEntity> source, 
                                                    string orderByProperty, bool desc)
{
    string command = desc ? "OrderByDescending" : "OrderBy";
    var type = typeof(TEntity);
    var property = type.GetProperty(orderByProperty);
    var parameter = Expression.Parameter(type, "p");
    var propertyAccess = Expression.MakeMemberAccess(parameter, property);
    var orderByExpression = Expression.Lambda(propertyAccess, parameter);
    var resultExpression = Expression.Call(typeof(Queryable), command, 
                                           new[] { type, property.PropertyType },
                                           source.AsQueryable().Expression, 
                                           Expression.Quote(orderByExpression));
    return source.AsQueryable().Provider.CreateQuery<TEntity>(resultExpression);
}

First Install Dynamic Tools --> NuGet Package Manager --> Package Manager Console

install-package System.Linq.Dynamic

Add Namespace using System.Linq.Dynamic;

Now you can use OrderBy("Name, Age DESC")

Thanks to Maarten (Query a collection using PropertyInfo object in LINQ) I got this solution:

myList.OrderByDescending(x => myPropertyInfo.GetValue(x, null)).ToList();

In my case I was working on a "ColumnHeaderMouseClick" (WindowsForm) so just found the specific Column pressed and its correspondent PropertyInfo:

foreach (PropertyInfo column in (new Process()).GetType().GetProperties())
{
    if (column.Name == dgvProcessList.Columns[e.ColumnIndex].Name)
    {}
}

OR

PropertyInfo column = (new Process()).GetType().GetProperties().Where(x => x.Name == dgvProcessList.Columns[e.ColumnIndex].Name).First();

(be sure to have your column Names matching the object Properties)

Cheers