How to return 0 value?

kieky bouvier

15y9.4k.NET

hi all...i need your help..
i'm using method to count total comment in my application.

This is my code :

Comment.aspx
ItemStyle-HorizontalAlign="Left" HeaderStyle-Width="15%" ItemStyle-Wrap="false">

<%#GetCountComment(Convert.ToString(Eval("IdTopic")))%>

Comment.aspx.cs
protected String GetCountComment(string IdTopik)
{
try
{
string value = String.Empty;

DMSDataAccess db = new DMSDataAccess();
var comment = db.DMSDataContext.Comments.Where(p => Convert.ToString(p.IdTopic) == IdTopic);

value = Convert.ToString(comment.Count());
return value;
}
catch (Exception e)
{
return e.ToString();
}
}

i think my code is correct.. but it can't display "0" value.. Can u help me to fix it??

thanks before...

33 Replies

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kieky bouvier15y ago
@Jonathas...
your code not working too if comment.Count() == 0
oh, what should i do? :(

@Vulpes...
you're right.. It really is a baffling problem..:(
Jonathas Sucupira15y ago
try
{
id_document = Convert.ToInt32(Request.QueryString[0]);
string username = HttpContext.Current.User.Identity.Name;
DMSDataAccess db = new DMSDataAccess()
var data = db.DMSDataContext.Topics.Select(p=>p).OrderByDescending(p=>p.CreatedOn).
Where(p=>p.IdDocument == id_document);

GridView_Main.PageSize = itemPerPage;
GridView_Main.PageIndex = NewPageIndex;
GridView_Main.DataSource = data;
GridView_Main.DataBind();
}
catch{}
}

After looking at this in more detail, are you binding the data to the grid after you calculated the value for getcommentcount?
Jonathas Sucupira15y ago
would you try this. Add this to the gridview OnDataBound="GridBound"

then

protected void GridBound(object sender, EventArgs e)
{
string IDTopik;
IDTopik = GridView1.DataKeys[0].ToString();

GetCountComment(IDTopik);
Response.Write("
The IdTopic received was: " + IDTopik);
}

protected string GetCountComment(string IdTopik)
{
try
{
string value = String.Empty;

DMSDataAccess db = new DMSDataAccess();
var comment = db.DMSDataContext.Comments.Where(p => Convert.ToString(p.IdTopic) == IdTopic);

value = Convert.ToString(comment.Count());

Response.Write("
The Value now is: " + value);

if (value == null || value == string.Empty) {
value = "0";
}

return value;
}
catch (Exception e)
{
Response.Write("
An Exception occured: ");
return e.ToString();
}

}
kieky bouvier15y ago
Jonathas,

this is my code :
protected void GridView_Main_DataBind(int NewPageIndex)
{
try
{
id_document = Convert.ToInt32(Request.QueryString[0]);
string username = HttpContext.Current.User.Identity.Name;
DMSDataAccess db = new DMSDataAccess()
var data = db.DMSDataContext.Topics.Select(p=>p).OrderByDescending(p=>p.CreatedOn).
Where(p=>p.IdDocument == id_document);

GridView_Main.PageSize = itemPerPage;
GridView_Main.PageIndex = NewPageIndex;
GridView_Main.DataSource = data;
GridView_Main.DataBind();
}
catch{}
}

and DataKeyNames="IdTopic"
Vulpes15y ago
The same thought occurred to me, Jonathas, but then when Count() > 0 she is seeing a number displayed.

It really is a baffling problem!
Jonathas Sucupira15y ago
I am thinking that your function is not been called? have you tried putting a breakpoint at the beginning of the function?
Vulpes15y ago
It looks like we can therefore rule out the possibility that an exception is somehow being thrown.

Did you try changing the method to return an int rather than a string?
kieky bouvier15y ago
vulpes.. yeah.. you're right.. i should be type "Trim".. not "trim"..

Suthish : i've tried your code.. but the output was still return empty value... :(
kieky bouvier15y ago
Vulpes.. an exception isn't getting anything.. i just get empty value..
its really really make me confused...
Jonathas Sucupira15y ago
How are you binding the data to the gridview? how is the grid getting the IdTopic?
Vulpes15y ago
One other thought.

Suppose an exception is getting thrown but, for some unknown reason, e.ToString() is returning an empty string rather than the normal error message.

Going back to your original code, kieky, try this:

protected String GetCountComment(string IdTopik)
{
   try
   {
   string value = String.Empty;

   DMSDataAccess db = new DMSDataAccess();
   var comment = db.DMSDataContext.Comments.Where(p => Convert.ToString(p.IdTopic) == IdTopic);

   value = Convert.ToString(comment.Count());
   return value;
   }
   catch (Exception e)
   {
   return "0";
   }
}
Vulpes15y ago
kieky,

Regarding the "cannot convert from 'string' to 'System.IFormatProvider" error, it sounds like you've omitted to change the return type of the method from string to int. The 'N0' format only works when converting ints to strings.

Regarding, Suthish's suggestion 'trim' should be 'Trim'.

I thought at first that the output (or lack of it) that you were getting from Jonathas' suggestion might be significant but when I tried setting PostCount to values other than "0", the output was still blank!

It's simply not possible for the Count() extension method to return anything other than an integer. If the sequence it's applied to is empty, Count will return zero. If the sequence is null, you'll get an exception.
kieky bouvier15y ago
Suthish Nair, thx 4 your replY..

hey, i got this
'string' does not contain a definition for 'trim' and no extension method 'trim' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)
kieky bouvier15y ago
Vulpes, i've tried your code nd i got 2 error : 1. cannot convert from 'string' to 'System.IFormatProvider' 2. The best overloaded method match for 'string.ToString(System.IFormatProvider)' has some invalid arguments whats wrong?
kieky bouvier15y ago
Jonathas.. i've tried your code.. and i got empty Post count if comment.Count() == 0
kieky bouvier15y ago
Jonathas,
hey.. i think it because var comment is null.. so comment.Count() does not work..
do u think it possible?
Suthish Nair15y ago
return (comment.Count().ToString().trim() == "") ? "0" : comment.Count().ToString();
Vulpes15y ago
One other idea I had was for the method to return an int rather than a string which you could then attempt to display as a string using the 'N0' format:

<%#GetCountComment(Convert.ToString(Eval("IdTopic"))).ToString("N0")%>

protected int GetCountComment(string IdTopik)
{
  try
  {
   DMSDataAccess db = new DMSDataAccess();
   var comment = db.DMSDataContext.Comments.Where(p => Convert.ToString(p.IdTopic) == IdTopic);
   return comment.Count();
  }
  catch (Exception e)
  {
   return -1;
  }
}
Jonathas Sucupira15y ago
Try this

ItemStyle-HorizontalAlign="Left" HeaderStyle-Width="15%" ItemStyle-Wrap="false">
<%#GetCountComment(Convert.ToString(Eval("IdTopic")))%>
Post count = <%# PostCount %>

public partial class Comment : System.Web.UI.Page
{
   public string PostCount;
   protected void Page_Load(object sender, EventArgs e)
   {

   }

   protected String GetCountComment(string IdTopik)
   {
   try
   {
   string value = String.Empty;

   DMSDataAccess db = new DMSDataAccess();
   var comment = db.DMSDataContext.Comments.Where(p => Convert.ToString(p.IdTopic) == IdTopic);

   value = Convert.ToString(comment.Count());

   if (value == null || value == string.Empty)
   {
   value = "0";
   }

   PostCount = value;

   return value;
   }
   catch (Exception e)
   {
   return e.ToString();
   }
   }
}
Jonathas Sucupira15y ago
You can add the breakpoint on the return line and run the debugger. once it stops there you need to mouseover the value and see what it says
kieky bouvier15y ago
JOnathas, do u mean breakpoint?
i dont know how to check value using breakpoint..
can u tell me that way?
Vulpes15y ago
If it's not the method, then the problem must lie with the binding tag.

To get around it, I think you need to cache the value of <%#Eval("IdTopic")%> in a separate variable (you could try a label to start with) and then pass that variable to your method using an 'ordinary' tag:

<%=GetCountComment(Convert.ToString(someVariable))%>
Jonathas Sucupira15y ago
Have you tried to step through the code to see if the problem is on the value been returned or the value been displayed?

I would put a break on the return line to see what the value was at that time.
kieky bouvier15y ago
Vulpes..
yeahh..you're right.. with <%=GetCountComment(Convert.ToString(null))%> all value return "0".. :)
so, do u know what is the problem?
kieky bouvier15y ago
Jonathas, thx for your replay..
your code look correct.. but it can't display "0" too... :'(
kieky bouvier15y ago
Vulpes, I try changing: <%=GetCountComment(Convert.ToString(<%#Eval("IdTopic")%>))%>
and get this error :
"Preprocessor directives must appear as the first non-whitespace character on a line"
Vulpes15y ago
Sorry, my last post was a bit rushed and I forgot to place quotes around the inner tags (now corrected) but I don't think it'll work anyway :(

What I am confident about is that it's nothing to do with the method.

I suspect if you try this, the "0" will be displayed:

<%=GetCountComment(Convert.ToString(null))%>
Jonathas Sucupira15y ago
Try this

protected String GetCountComment(string IdTopik)
{
try
{
string value = String.Empty;

DMSDataAccess db = new DMSDataAccess();
var comment = db.DMSDataContext.Comments.Where(p => Convert.ToString(p.IdTopic) == IdTopic);

value = Convert.ToString(comment.Count());

if (value == null || value == string.Empty) {
value = "0";
}

return value;
}
catch (Exception e)
{
return e.ToString();
}
}
Vulpes15y ago
It must be something to do with the 'binding' tag you're using. See if the following's any better:

<%=GetCountComment(Convert.ToString('<%#Eval("IdTopic")%>'))%>

EDITED: To place quotes around inner tags
kieky bouvier15y ago
yes.. it just empty space...
but if comment.Count() > 0, it can display total coment correctly
Vulpes15y ago
What does it display, just an empty space?

Also do other numbers display correctly?

If nothing's been displayed at all, I'd try changing:

<%#GetCountComment(Convert.ToString(Eval("IdTopic")))%>

to:

<%=GetCountComment(Convert.ToString(Eval("IdTopic")))%>
kieky bouvier15y ago
hi vulpes.. thanks for your replay..
your code can't dislay "0" too... :'(
oh, no! it make me confused...
Vulpes15y ago
I can't see any reason why shouldn't be able to display "0" with that code if there are no comments returned by the query:-/

However, try this instead:

protected String GetCountComment(string IdTopik)
{
try
{
string value = "0";

DMSDataAccess db = new DMSDataAccess();
var comment = db.DMSDataContext.Comments.Where(p => Convert.ToString(p.IdTopic) == IdTopic);

int temp = comment.Count();
if (temp > 0) value = Convert.ToString(temp);
return value;
}
catch (Exception e)
{
return e.ToString();
}