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Sort an observable collection of type T where T will change on run time (generics)

Hello I want to sort an ObservableCollection but I cant get access to its properties.
public static class CommonMethods<T>
{
public static ObservableCollection<T> Sort(ObservableCollection<T> array, string columnName, bool sort)
{
ObservableCollection<T> res = new ObservableCollection<T>();
res = res.OrderBy(r => r[""]) // This gives an error says cannot apply indexing with [] to an expression of type T.
return res;
}
}
The Calling code.
mlRegionDetails = CommonMethods<MLRegion>.Sort(mlRegionDetails, columnName, sort);
Please do tell me where I m going wrong.

Instead of passing the name of the property you want to order by, pass the selector function:
public static ObservableCollection<T> Sort(ObservableCollection<T> array, Func<T, object> columnSelector, bool sort)
{
ObservableCollection<T> res = new ObservableCollection<T>(array.OrderBy(columnSelector));
return res;
}
And call it using this:
mlRegionDetails = CommonMethods<MLRegion>.Sort(mlRegionDetails, x => x.SomeColumn, sort);
If you want to do this using strings, you will need to build the expression manually.
Note: the following code has not been tested as it was written here, it may need some change.
public static class CommonMethods<T>
{
private static readonly MethodInfo orderByMethod =
typeof(Enumerable).GetMethods().Single(method =>
method.Name == nameof(Enumerable.OrderBy) && method.GetParameters().Length == 2);
public static ObservableCollection<T> Sort(ObservableCollection<T> array, string columnName, bool sort)
{
var tType = typeof(T);
var parameter = Expression.Parameter(tType);
Expression member = Expression.Property(parameter, columnName);
var lambda = Expression.Lambda(member, paramter);
var genericMethod = orderByMethod.MakeGenericMethod(tType, member.Type);
var orderedData = genericMethod.Invoke(null, new object[] { array, lambda }) as IEnumerable<T>;
return new ObservableCollection<T>(orderedData);
}
}

At last i found an alternate solution to the problem. I create a temp var then convert that ObservableCollection to AsEnumerable and ordering it by the Key passed to it.
Creating key part credit goes to #Camilo Terevinto
public static class CommonMethods
{
public static ObservableCollection<T> sort<T>(ObservableCollection<T> array, Func<T, object> key)
{
var res = array.AsEnumerable().OrderByDescending(key); ;
ObservableCollection<T> temp = new ObservableCollection<T>(res);
return temp;
}
}

Improve sorting with linq [duplicate]

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 into this oldie...
To do this without the dynamic LINQ library, you just need the code as below. This covers most common scenarios including nested properties.
To get it working with IEnumerable<T> you could add some wrapper methods that go via AsQueryable - but the code below is the core Expression logic needed.
public static IOrderedQueryable<T> OrderBy<T>(
this IQueryable<T> source,
string property)
{
return ApplyOrder<T>(source, property, "OrderBy");
}
public static IOrderedQueryable<T> OrderByDescending<T>(
this IQueryable<T> source,
string property)
{
return ApplyOrder<T>(source, property, "OrderByDescending");
}
public static IOrderedQueryable<T> ThenBy<T>(
this IOrderedQueryable<T> source,
string property)
{
return ApplyOrder<T>(source, property, "ThenBy");
}
public static IOrderedQueryable<T> ThenByDescending<T>(
this IOrderedQueryable<T> source,
string property)
{
return ApplyOrder<T>(source, property, "ThenByDescending");
}
static IOrderedQueryable<T> ApplyOrder<T>(
IQueryable<T> source,
string property,
string methodName)
{
string[] props = property.Split('.');
Type type = typeof(T);
ParameterExpression arg = Expression.Parameter(type, "x");
Expression expr = arg;
foreach(string prop in props) {
// use reflection (not ComponentModel) to mirror LINQ
PropertyInfo pi = type.GetProperty(prop);
expr = Expression.Property(expr, pi);
type = pi.PropertyType;
}
Type delegateType = typeof(Func<,>).MakeGenericType(typeof(T), type);
LambdaExpression lambda = Expression.Lambda(delegateType, expr, arg);
object result = typeof(Queryable).GetMethods().Single(
method => method.Name == methodName
&& method.IsGenericMethodDefinition
&& method.GetGenericArguments().Length == 2
&& method.GetParameters().Length == 2)
.MakeGenericMethod(typeof(T), type)
.Invoke(null, new object[] {source, lambda});
return (IOrderedQueryable<T>)result;
}
Edit: it gets more fun if you want to mix that with dynamic - although note that dynamic only applies to LINQ-to-Objects (expression-trees for ORMs etc can't really represent dynamic queries - MemberExpression doesn't support it). But here's a way to do it with LINQ-to-Objects. Note that the choice of Hashtable is due to favorable locking semantics:
using Microsoft.CSharp.RuntimeBinder;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Dynamic;
using System.Linq;
using System.Runtime.CompilerServices;
static class Program
{
private static class AccessorCache
{
private static readonly Hashtable accessors = new Hashtable();
private static readonly Hashtable callSites = new Hashtable();
private static CallSite<Func<CallSite, object, object>> GetCallSiteLocked(
string name)
{
var callSite = (CallSite<Func<CallSite, object, object>>)callSites[name];
if(callSite == null)
{
callSites[name] = callSite = CallSite<Func<CallSite, object, object>>
.Create(Binder.GetMember(
CSharpBinderFlags.None,
name,
typeof(AccessorCache),
new CSharpArgumentInfo[] {
CSharpArgumentInfo.Create(
CSharpArgumentInfoFlags.None,
null)
}));
}
return callSite;
}
internal static Func<dynamic,object> GetAccessor(string name)
{
Func<dynamic, object> accessor = (Func<dynamic, object>)accessors[name];
if (accessor == null)
{
lock (accessors )
{
accessor = (Func<dynamic, object>)accessors[name];
if (accessor == null)
{
if(name.IndexOf('.') >= 0) {
string[] props = name.Split('.');
CallSite<Func<CallSite, object, object>>[] arr
= Array.ConvertAll(props, GetCallSiteLocked);
accessor = target =>
{
object val = (object)target;
for (int i = 0; i < arr.Length; i++)
{
var cs = arr[i];
val = cs.Target(cs, val);
}
return val;
};
} else {
var callSite = GetCallSiteLocked(name);
accessor = target =>
{
return callSite.Target(callSite, (object)target);
};
}
accessors[name] = accessor;
}
}
}
return accessor;
}
}
public static IOrderedEnumerable<dynamic> OrderBy(
this IEnumerable<dynamic> source,
string property)
{
return Enumerable.OrderBy<dynamic, object>(
source,
AccessorCache.GetAccessor(property),
Comparer<object>.Default);
}
public static IOrderedEnumerable<dynamic> OrderByDescending(
this IEnumerable<dynamic> source,
string property)
{
return Enumerable.OrderByDescending<dynamic, object>(
source,
AccessorCache.GetAccessor(property),
Comparer<object>.Default);
}
public static IOrderedEnumerable<dynamic> ThenBy(
this IOrderedEnumerable<dynamic> source,
string property)
{
return Enumerable.ThenBy<dynamic, object>(
source,
AccessorCache.GetAccessor(property),
Comparer<object>.Default);
}
public static IOrderedEnumerable<dynamic> ThenByDescending(
this IOrderedEnumerable<dynamic> source,
string property)
{
return Enumerable.ThenByDescending<dynamic, object>(
source,
AccessorCache.GetAccessor(property),
Comparer<object>.Default);
}
static void Main()
{
dynamic a = new ExpandoObject(),
b = new ExpandoObject(),
c = new ExpandoObject();
a.X = "abc";
b.X = "ghi";
c.X = "def";
dynamic[] data = new[] {
new { Y = a },
new { Y = b },
new { Y = c }
};
var ordered = data.OrderByDescending("Y.X").ToArray();
foreach (var obj in ordered)
{
Console.WriteLine(obj.Y.X);
}
}
}

Too easy without any complication:
Add using System.Linq.Dynamic; at the top.
Use vehicles = vehicles.AsQueryable().OrderBy("Make ASC, Year DESC").ToList();
Edit: to save some time, the System.Linq.Dynamic.Core (System.Linq.Dynamic is deprecated) assembly is not part of the framework, but can be installed from nuget: System.Linq.Dynamic.Core

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

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.

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 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().

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);

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}");

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")

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");

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;
}
}

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

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();
}

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.

You can define a dictionary from string to Func<> like this :
Dictionary<string, Func<Item, object>> SortParameters = new Dictionary<string, Func<Item, object>>()
{
{"Rank", x => x.Rank}
};
And use it like this :
yourList.OrderBy(SortParameters["Rank"]);
In this case you can dynamically sort by string.

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.

I am able to do this with the code below. No need write long and complex code.
protected void sort_array(string field_name, string asc_desc)
{
objArrayList= Sort(objArrayList, field_name, asc_desc);
}
protected List<ArrayType> Sort(List<ArrayType> input, string property, string asc_desc)
{
if (asc_desc == "ASC")
{
return input.OrderBy(p => p.GetType()
.GetProperty(property)
.GetValue(p, null)).ToList();
}
else
{
return input.OrderByDescending(p => p.GetType()
.GetProperty(property)
.GetValue(p, null)).ToList();
}
}

If you are using Specification (such as Ardalis Specification)
using Microsoft.EntityFrameworkCore;
namespace TestExtensions;
public static class IQueryableExtensions
{
public static void ApplyOrder<T>(ISpecificationBuilder<T> query, string propertyName, bool ascendingOrder)
{
if (ascendingOrder)
query.OrderBy(T => EF.Property<object>(T!, propertyName));
else
query.OrderByDescending(T => EF.Property<object>(T!, propertyName));
}
}

With Net6 and EF
.AsQueryable().OrderBy((ColumnOrder.Column, ColumnOrder.Dir));

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

How can i keep reference of a lambda expression that will be later passed to OrderBy or LoadWith functions?

I am trying to create a general method for accessing the DB. This will imply parameters like: page index, number of items to display per page, ordering options, load options etc.
...
public IQuerable<T> GetAll(int pageIndex, int itemsToDisplayPerPage, System.Linq.Expressions.Expression<Func<T,object>>[] orderBy, System.Linq.Expressions.Expression<Func<T,object>>[] loadOptions)
{
DataContext dc = null;
IQuerable<T> result = null;
// Make some initalizations
...
foreach(var item in orderBy)
{
result = result.OrderBy(item);
}
System.Data.Linq.DataLoadOptions loadOptions = new System.Data.Linq.DataLoadOptions();
foreach(var item in loadOptions)
{
loadOptions.LoadWith(item);
}
...
}
...
The problem is that the System.Linq.Expressions.Expression< Func< T,object > > type is not a good general representation of any lambda expression that will be passed for the both examples above.
On ordering will crash because of the object type that does not make any sense for ordering. Also on loadWith will not work. So i dont know how can i handle this problem. Any suggestions? Thank you.

Not sure about the LoadWith, as we are using linq to entities, but we successfully got orderby to work in a repository Get method. The client code looks like this:
var results = _repository.GetAll(
new GetAllCriteria()
.OrderBy(x => x.Property1)
.OrderBy(x => x.Property2)
);
We aren't using generics in repository methods just yet, that will probably come in a future refactor. But the criteria implementation looks like this:
public class GetAllCriteria
{
public Dictionary<Expression<Func<CustomType, object>>, bool> ToBeOrderedBy
{
get; private set;
}
public GetAllCriteria OrderBy(
Expression<Func<CustomType, object>> expression)
{
return OrderBy(expression, true);
}
public GetAllCriteria OrderByDescending(
Expression<Func<CustomType, object>> expression)
{
return OrderBy(expression, false);
}
private GetAllCriteria OrderBy(
Expression<Func<CustomType, object>> expression, bool isAscending)
{
if (expression != null)
{
if (ToBeOrderedBy == null)
ToBeOrderedBy = new Dictionary<Expression<Func<CustomType, object>>, bool>();
ToBeOrderedBy.Add(expression, isAscending);
}
return this;
}
}
Then, the repository orders like so:
public Collection<CustomType> GetAll(GetAllCriteria criteria)
{
var query = dbContext.CustomTypes.AsQueryable();
// some code
// apply order by
if (criteria.ToBeOrderedBy != null && criteria.ToBeOrderedBy.Count > 0)
{
var firstOrderBy = criteria.ToBeOrderedBy.First();
query = firstOrderBy.Value
? query.OrderBy(firstOrderBy.Key)
: query.OrderByDescending(firstOrderBy.Key);
query = criteria.ToBeOrderedBy.Skip(1).Aggregate(query,
(lastOrderBy, nextOrderBy) => nextOrderBy.Value
? ((IOrderedQueryable<CustomType>)lastOrderBy)
.ThenBy(nextOrderBy.Key)
: ((IOrderedQueryable<CustomType>)lastOrderBy)
.ThenByDescending(nextOrderBy.Key));
}
// some more code
var results = query.ToList();
return results;
}
If this works with linq to entities, I would imagine it should work with linq to sql.

Filter entities, then sort on dynamic field

I'm trying to FIRST filter a set of products, then order them
(repository.GetAllProducts()
.Where(x=>x.Naam.Contains("filter")) as ObjectQuery<Product>)
.FunkyOrder<Product>(sortfield,sortdirection)
Using the Extension method:
public static IEnumerable<T> FunkyOrder<T>(this ObjectQuery<T> input, string fieldname = "Id", string sortdirection = "asc")
{
switch (sortdirection)
{
case "dsc":
case "desc":
return input.OrderBy("it." + fieldname + " DESC");
default:
return input.OrderBy("it." + fieldname);
}
}
(the GetAllProducts() of my Repository returns an IEnumerable
This FunkyOrder method should be working but that - as ObjectQuery - cast returns NULL
I can only use the FunkyOrder with ObjectQuery because that seems to be the only thing that supports those "it.FieldName" queries.
If I change the - as - notation to A regular cast I get:
Unable to cast object of type 'WhereEnumerableIterator`1[MySecretNameSpace.Product]' to type 'System.Data.Objects.ObjectQuery`1[MySecretNameSpace.Product]'.
Is there any way to make this work or will I be forced to either live with sorting before filtering, or write a giant switch with lambda expressions for my sorting?

This actually turned out to be a GIANT headache to try to solve; but in the end, it actually turned out being very easy to accomplish with a bit of hackishness and reflection:
public class Program
{
public class SomeClass
{
public int Id { get; set; }
public string Name { get; set; }
}
static void Main(string[] args)
{
List<SomeClass> sample = new List<SomeClass>
{
new SomeClass { Id = 4, Name = "ABC" },
new SomeClass { Id = 1, Name = "XYZ" },
new SomeClass { Id = 2, Name = "JKL" }
};
var result = sample.OrderByDynamic("Name", OrderDirection.Ascending).ToList();
result.ForEach(x => Console.WriteLine("Id: " + x.Id + " | Name: " + x.Name));
Console.ReadKey();
}
}
public enum OrderDirection
{
Ascending,
Descending
}
public static class LinqExtensions
{
public static IEnumerable<T> OrderByDynamic<T>(this IEnumerable<T> source, string propertyName, OrderDirection direction = OrderDirection.Ascending)
{
if(direction == OrderDirection.Ascending)
return source.OrderBy(x => x.GetType().GetProperty(propertyName).GetValue(x, null));
else
return source.OrderByDescending(x => x.GetType().GetProperty(propertyName).GetValue(x, null));
}
}
This example worked for me in test situations; I could supply the property name, and specify a sort direction, and it worked great. Simply call like so:
yourEnumerable.OrderByDynamic("YourPropertyName");
yourEnumerable.OrderByDynamic("YourPropertyName", OrderDirection.Descending);
Enjoy!

I would change your FunkyOrder method to IEnumerable and implement your dynamic sorting by creating an Expression dynamically like so
public static IEnumerable<T> FunkyOrder<T, TResult>(this IEnumerable<T> input, string fieldname = "Id", string sortdirection = "asc")
{
ParameterExpresssion parameter = Expression.Parameter(typeof(T), "p");
Expression property = Expression.PropertyOrField(parameter, fieldname);
var lambda = Expression.Lambda<Func<T, TResult>>(property, parameter)
if(sortdirection == "asc")
{
return input.OrderBy(lambda.Compile());
}
else
{
return input.OrderByDescending(lambda.Complile());
}
}
You will no longer need to cast to ObjectQuery

You can use Dynamic Linq for dynamic filtering and sorting. This small library (only one single source file) contains extension methods of IQueryable<T> like:
public static IQueryable<T> Where<T>(this IQueryable<T> source,
string predicate, params object[] values)
public static IQueryable<T> OrderBy<T>(this IQueryable<T> source,
string ordering, params object[] values)
//...and more like GroupBy, Select
Your query on IEnumerable could then be written as:
repository.GetAllProducts().AsQueryable()
.Where(x => x.Naam.Contains("filter"))
.OrderBy("FieldName desc")
The library implements all the necessary reflection code to perform those dynamic queries.

LINQ: Sorting on many columns dynamically

I have a query of IQueryable and want to apply sorting to it dynamically, sorting can be on many columns (asc or desc). I've written the following generic function:
private IQueryable<T> ApplySorting<T,U>(IQueryable<T> query, Expression<Func<T, U>> predicate, SortOrder order)
{
if (order == SortOrder.Ascending)
{
{
return query.OrderBy<T, U>(predicate);
}
}
else
{
{
return query.OrderByDescending<T, U>(predicate);
}
}
}
SortOrder is my simple enum with 2 values: Ascending and Descending
Then I call this function in a loop, for each column that user requested sorting. However I've noticed it fails because it always sorts on the last column used, ignoring the other ones.
Then I found there's a 'ThenBy' method on IOrderedQueryable so the valid usage is:
var q = db.MyType.OrderBy(x=>x.Col1).ThenBy(y=>y.Col2); //etc.
But how can I make it generic? I tried to test if the query is IOrderedQueryable but it seems always to be true even if it's simplest var q = from x in db.MyType select x
I have no clue why it was designed like this. What's wrong with:
var q = db.MyType.OrderBy(x=>x.Col1).OrderBy(y=>y.Col2); //etc.
it's so much intuitive

You just need to check if the query is already ordered :
private IQueryable<T> ApplySorting<T,U>(IQueryable<T> query, Expression<Func<T, U>> predicate, SortOrder order)
{
var ordered = query as IOrderedQueryable<T>;
if (order == SortOrder.Ascending)
{
if (ordered != null)
return ordered.ThenBy(predicate);
return query.OrderBy(predicate);
}
else
{
if (ordered != null)
return ordered.ThenByDescending(predicate);
return query.OrderByDescending(predicate);
}
}

How about just making the first OrderBy static, then always ThenBy?
OrderColumn[] columnsToOrderby = getColumnsToOrderby();
IQueryable<T> data = getData();
if(!columnToOrderBy.Any()) { }
else
{
OrderColumn firstColumn = columnsToOrderBy[0];
IOrderedEnumerable<T> orderedData =
firstColumn.Ascending
? data.OrderBy(predicate)
: data.OrderByDescending(predicate);
for (int i = 1; i < columnsToOrderBy.Length; i++)
{
OrderColumn column = columnsToOrderBy[i];
orderedData =
column.Ascending
? orderedData.ThenBy(predicate)
: orderedData.ThenByDescending(predicate);
}
}

Total guess, but can you do something like this?
query.OrderBy(x => 1).ThenBy<T,U>(predicate)
Any syntax errors aside, the idea is to do an OrderBy() that doesn't affect anything, then do the real work in the .ThenBy() method call

I would write a wrapper around and internally use linq extension methods.
var resultList = presentList
.MyOrderBy(x => x.Something)
.MyOrderBY(y => y.SomethingElse)
.MyOrderByDesc(z => z.AnotherThing)
public IQueryable<T> MyOrderBy(IQueryable<T> prevList, Expression<Func<T, U>> predicate) {
return (prevList is IOrderedQueryable<T>)
? query.ThenBy(predicate)
: query.OrderBy(predicate);
}
public IQueryable<T> MyOrderByDesc(IQueryable<T> prevList, Expression<Func<T, U>> predicate) {
return (prevList is IOrderedQueryable<T>)
? query.ThenByDescending(predicate)
: query.OrderByDescending(predicate);
}
PS: I didn't test the code

Extension to dynamic multi-order:
public static class DynamicExtentions
{
public static IEnumerable<T> DynamicOrder<T>(this IEnumerable<T> data, string[] orderings) where T : class
{
var orderedData = data.OrderBy(x => x.GetPropertyDynamic(orderings.First()));
foreach (var nextOrder in orderings.Skip(1))
{
orderedData = orderedData.ThenBy(x => x.GetPropertyDynamic(nextOrder));
}
return orderedData;
}
public static object GetPropertyDynamic<Tobj>(this Tobj self, string propertyName) where Tobj : class
{
var param = Expression.Parameter(typeof(Tobj), "value");
var getter = Expression.Property(param, propertyName);
var boxer = Expression.TypeAs(getter, typeof(object));
var getPropValue = Expression.Lambda<Func<Tobj, object>>(boxer, param).Compile();
return getPropValue(self);
}
}
Example:
var q =(myItemsToSort.Order(["Col1","Col2"]);
Note: not sure any IQueryable provider can translate this