在插入数据库之前检查文本框中的空值

Question

I have a windows form application. in which there is one form, which has about 20+ textbox's, i want to verify weather the values are null or not. if values are null than error provider shoud point to which textbox is the culprit. else store the data to the database.

I have created a function called "null2" and i'm calling it button click, just before executing the endexecutequery method.

here is my code:

    public bool null2 (Control control)
    {

        foreach (Control C in control.Controls)
        {
            if (C is TextBox)
            {
                TextBox textbox = C as TextBox;
                if (string.IsNullOrWhiteSpace(textbox.Text))
                {

                    return(false) ;
                }
                else
                {
                    MessageBox.Show("Not happening bro...");
                    errorProvider1.SetError(textbox, "Cannot be Empty");
                    return(false) ;
                }
            }
            else
            {
               return (false);
            }
        }
        return(true);

    }

on button click here

if (!null2(this))
          {
             // MessageBox.Show("Some empty values are present");
              try
              {
                  int resul = subcom.ExecuteNonQuery();
                  if (resul > 0)
                  {
                      MessageBox.Show("Entered Successfully");
                  }
              }
              catch
              {
                  MessageBox.Show("Some details missing");
              }
         }
         else
        {
            MessageBox.Show("Some empty values are present");
         }

Answer 1

Probably you have your checks wrong. If the control text is empty (the text property of a TextBox is never null) you should emit your warning, set the error provider and return false exiting from the loop. Otherwise you end the loop (meaning no TextBox is empty) and return true

public bool null2 (Control control) 
{
    foreach (TextBox t in control.Controls.OfType<TextBox>())
    {
        if (string.IsNullOrWhiteSpace(t.Text))
        {
            MessageBox.Show("Not happening bro...");
            errorProvider1.SetError(t, "Cannot be Empty");
            return(false) ;
        }
    }
    return(true);
}

Also notice how using IEnumerable.OfType will simplify your code a lot

However, this code doesn't attempt to store anything in the database, so the real problem is in the code that calls this function and how that code handles the return as false from here

EDIT Change the code in your comment below to this

if (null2(this)) 
{ 
   // If null2 returns true, then execute the query, 
   // there is no need to add another message box for the 
   // empty condition, you have already said that in the null2 method
   try 
   { 
       int resul = subcom.ExecuteNonQuery(); 
       if (resul > 0) 
       { 
           MessageBox.Show("Entered Successfully"); 
       } 
   } 
   catch (Exception ex)
   { 
       MessageBox.Show(ex.Message); 
   }
}

please add the code in your comment below to your original question above