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sort list of objects by object property name

Posted on 2015-01-16
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Last Modified: 2016-02-16
I have a list of objects, defined as

List<CCG_QuantityCheckData> badItems = new List<CCG_QuantityCheckData>();

I'm populating my badItems list like:

badItems.Add(item);

where item is defined as:

foreach (CCG_QuantityCheckData item in CCG_Items)

I want to sort on each objects "balance_on_hand" property, so I tried using LINQ:

badItems = badItems.OrderBy(x >= x.balance_on_hand).ToList();

which yields the message:

The type arguments for method 'System.Linq.Enumerable.OrderBy<TSource,TKey>(System.Collections.Generic.IEnumerable<TSource>, System.Func<TSource,TKey>)' cannot be inferred from the usage. Try specifying the type arguments explicitly.      

what am I doing wrong?
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Question by:Big Monty
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10 Comments
 
LVL 34

Expert Comment

by:Mike Eghtebas
ID: 40554423
Have you tried:

badItems.Sort()

I found this example on the Web:
class Program
{
    static void Main()
    {
	List<string> list = new List<string>();
	list.Add("tuna");
	list.Add("velvetfish");
	list.Add("angler");

	// Sort fish alphabetically, in ascending order (A - Z)
	list.Sort();

	foreach (string value in list)
	{
	    Console.WriteLine(value);
	}
    }
}

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LVL 34

Author Comment

by:Big Monty
ID: 40554479
I looked at Sort() but couldn't figure out how to sort via an object property.

in your example, you just have a list of strings, i need to sort a list of objects
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LVL 34

Accepted Solution

by:
Mike Eghtebas earned 1000 total points
ID: 40554495
My bad, try:

List<CCG_QuantityCheckData> SortedObjList = badItems.OrderBy(o=>o.balance_on_hand).ToList();

I am building an example to make sure this works.
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LVL 34

Expert Comment

by:Mike Eghtebas
ID: 40554590
This example works (I have used the above solution, compare it with line 24 below):
namespace List
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Order> objListOrder = new List<Order>();
            Order ord1 = new Order();
            Order ord2 = new Order();
            Order ord3 = new Order();

            ord1.OrderId = 5;
            ord2.OrderId = 100;
            ord3.OrderId = 33;

            ord1.OrderDate = new DateTime(2014, 1, 1);
            ord2.OrderDate = new DateTime(2013, 3, 1);
            ord3.OrderDate = new DateTime(2012, 2, 1);
             
            objListOrder.Add(ord1);
            objListOrder.Add(ord2);
            objListOrder.Add(ord3);

            List<Order> newList = objListOrder.OrderBy(o => o.OrderId).ToList();

            ShowDates(newList);

        }

        public  static void  ShowDates(List<Order> mylist)
        {
            foreach (Order o in mylist)
            {
                Console.WriteLine(o.OrderId.ToString());
            }

            Console.ReadLine();
        }
         
    }
}

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LVL 64

Assisted Solution

by:Fernando Soto
Fernando Soto earned 1000 total points
ID: 40554716
Hi Big Monty;

The issue you may be having is that the method OrderBy takes a lambda expression but the operator you have used is a greater then or equal, >=, where it should have been,  =>.

Your code was
badItems = badItems.OrderBy(x >= x.balance_on_hand).ToList();

should be
badItems = badItems.OrderBy(x => x.balance_on_hand).ToList();
0
 
LVL 34

Expert Comment

by:Mike Eghtebas
ID: 40554759
Fernando,

Thank you for pointing that out. I got to have some free education also.

Mike
0
 
LVL 64

Expert Comment

by:Fernando Soto
ID: 40554761
@Mike, I can't tell you how many times that has happened to me. Well all learn from woking on these post. ;=)
0
 
LVL 34

Expert Comment

by:Mike Eghtebas
ID: 40554842
Fernando,

One think that makes you very good (but I haven't learned enough on it to be like you yet) is that you read the error message very closely. And, that seems to be your key to success.

Mike
0
 
LVL 34

Author Closing Comment

by:Big Monty
ID: 40555731
thx to both, that was the issue and it's now resolved
0
 
LVL 64

Expert Comment

by:Fernando Soto
ID: 40555843
Not a problem, glad to have been of help.
0

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