At least one object must implement IComparable

Currently I had meet a problem as the title above. It is really weird, because I also had use the Group By and toList() function in the other process and not error pop up.

The coding is as below :

//Get the Detail by grouping with article number, color and category.
                



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//Get the Detail by grouping with article number, color and category.  
var DetailGroup = detail.GroupBy(c => new { c.ARTICLE_NUMBER, c.COLOR, c.CATEGORY, c.UOM })  
.OrderByDescending(o => new { o.Key.ARTICLE_NUMBER, o.Key.COLOR }).ToList();  

After looking for the online resources, I find this Article and just realize that it maybe is not about the Group By but the Order By (multiple order by in the group by). 

So that, I modify a bit the coding (add in ThenBy) :

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1. //Get the Detail by grouping with article number, color and category.  
2. var DetailGroup = detail.GroupBy(c => new { c.ARTICLE_NUMBER, c.COLOR, c.CATEGORY, c.UOM })  
3. .OrderByDescending(o =>o.Key.ARTICLE_NUMBER).ThenBy( o =>  o.Key.COLOR ).ToList();  

and it is work fine and faster.


Hope this can help you and have a nice day. :)

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This article from: http://oysterleelife.blogspot.sg/2012/11/solved-at-least-one-object-must.html

C# Winform Handle Double Click

To distinguish between clicks in the MouseDown event

• Handle the MouseDown event and determine the location and time span between clicks using the appropriate SystemInformation properties and a Timer component. Perform the appropriate action depending on whether a click or double-click takes place. The following code example demonstrates how this can be done.
  C#

  C++

  VB

  using System;
  using System.Drawing;
  using System.Windows.Forms;
  
  namespace SingleVersusDoubleClick
  {
      class Form1 : Form
      {
          private Rectangle hitTestRectangle = new Rectangle();
          private Rectangle doubleClickRectangle = new Rectangle();
          private TextBox textBox1 = new TextBox();
          private Timer doubleClickTimer = new Timer();
          private ProgressBar doubleClickBar = new ProgressBar();
          private Label label1 = new Label();
          private Label label2 = new Label();
          private bool isFirstClick = true;
          private bool isDoubleClick = false;
          private int milliseconds = 0;
  
          [STAThread]
          public static void Main()
          {
              Application.EnableVisualStyles();
              Application.Run(new Form1());
          }
  
          public Form1()
          {
              label1.Location = new Point(30, 5);
              label1.Size = new Size(100, 15);
              label1.Text = "Hit test rectangle:";
  
              label2.Location = new Point(30, 70);
              label2.Size = new Size(100, 15);
              label2.Text = "Double click timer:";
  
              hitTestRectangle.Location = new Point(30, 20);
              hitTestRectangle.Size = new Size(100, 40);
  
              doubleClickTimer.Interval = 100;
              doubleClickTimer.Tick +=
                  new EventHandler(doubleClickTimer_Tick);
  
              doubleClickBar.Location = new Point(30, 85);
              doubleClickBar.Minimum = 0;
              doubleClickBar.Maximum = SystemInformation.DoubleClickTime;
  
              textBox1.Location = new Point(30, 120);
              textBox1.Size = new Size(200, 100);
              textBox1.AutoSize = false;
              textBox1.Multiline = true;
  
              this.Paint += new PaintEventHandler(Form1_Paint);
              this.MouseDown += new MouseEventHandler(Form1_MouseDown);
              this.Controls.AddRange(new Control[] { doubleClickBar, textBox1, 
                  label1, label2 });
          }
  
          // Detect a valid single click or double click. 
          void Form1_MouseDown(object sender, MouseEventArgs e)
          {
              // Verify that the mouse click is in the main hit 
              // test rectangle. 
              if (!hitTestRectangle.Contains(e.Location))
              {
                  return;
              }
  
              // This is the first mouse click. 
              if (isFirstClick)
              {
                  isFirstClick = false;
  
                  // Determine the location and size of the double click  
                  // rectangle area to draw around the cursor point.
                  doubleClickRectangle = new Rectangle(
                      e.X - (SystemInformation.DoubleClickSize.Width / 2),
                      e.Y - (SystemInformation.DoubleClickSize.Height / 2),
                      SystemInformation.DoubleClickSize.Width,
                      SystemInformation.DoubleClickSize.Height);
                  Invalidate();
  
                  // Start the double click timer.
                  doubleClickTimer.Start();
              }
  
              // This is the second mouse click. 
              else
              {
                  // Verify that the mouse click is within the double click 
                  // rectangle and is within the system-defined double  
                  // click period. 
                  if (doubleClickRectangle.Contains(e.Location) &&
                      milliseconds < SystemInformation.DoubleClickTime)
                  {
                      isDoubleClick = true;
                  }
              }
          }
  
          void doubleClickTimer_Tick(object sender, EventArgs e)
          {
              milliseconds += 100;
              doubleClickBar.Increment(100);
  
              // The timer has reached the double click time limit. 
              if (milliseconds >= SystemInformation.DoubleClickTime)
              {
                  doubleClickTimer.Stop();
  
                  if (isDoubleClick)
                  {
                      textBox1.AppendText("Perform double click action");
                      textBox1.AppendText(Environment.NewLine);
                  }
                  else
                  {
                      textBox1.AppendText("Perform single click action");
                      textBox1.AppendText(Environment.NewLine);
                  }
  
                  // Allow the MouseDown event handler to process clicks again.
                  isFirstClick = true;
                  isDoubleClick = false;
                  milliseconds = 0;
                  doubleClickBar.Value = 0;
              }
          }
  
          // Paint the hit test and double click rectangles. 
          void Form1_Paint(object sender, PaintEventArgs e)
          {
              // Draw the border of the main hit test rectangle.
              e.Graphics.DrawRectangle(Pens.Black, hitTestRectangle);
  
              // Fill in the double click rectangle.
              e.Graphics.FillRectangle(Brushes.Blue, doubleClickRectangle);
          }
      }
  }