How to return 0 value?

Question

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

This is my code :

Comment.aspx
<asp:TemplateField HeaderText="Comment" ItemStyle-CssClass="GridviewItem" ItemStyle-VerticalAlign="Top"
ItemStyle-HorizontalAlign="Left" HeaderStyle-Width="15%" ItemStyle-Wrap="false">
<ItemTemplate>
<%#GetCountComment(Convert.ToString(Eval("IdTopic")))%>
</ItemTemplate>
<HeaderStyle Width="15%" />
<ItemStyle CssClass="GridviewItem" HorizontalAlign="Center" VerticalAlign="Top" Wrap="False" />
</asp:TemplateField>

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...

kieky bouvier · Answer

@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 Sucupira · Answer

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 Sucupira · Answer

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 bouvier · Answer

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"

Vulpes · Answer

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 Sucupira · Answer

I am thinking that your function is not been called? have you tried putting a breakpoint at the beginning of the function?

Vulpes · Answer

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 bouvier · Answer

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 bouvier · Answer

Vulpes.. an exception isn't getting anything.. i just get empty value.. its really really make me confused...

Jonathas Sucupira · Answer

How are you binding the data to the gridview? how is the grid getting the IdTopic?

Vulpes · Answer

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"; } }

Vulpes · Answer

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 bouvier · Answer

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 bouvier · Answer

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 bouvier · Answer

Jonathas.. i've tried your code.. and i got empty Post count if comment.Count() == 0

kieky bouvier · Answer

Jonathas, hey.. i think it because var comment is null.. so comment.Count() does not work.. do u think it possible?

Suthish Nair · Answer

return (comment.Count().ToString().trim() == "") ? "0" : comment.Count().ToString();

Vulpes · Answer

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: 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 Sucupira · Answer

Try this ItemStyle-HorizontalAlign="Left" HeaderStyle-Width="15%" ItemStyle-Wrap="false"> Post count = 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 Sucupira · Answer

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 bouvier · Answer

JOnathas, do u mean breakpoint? i dont know how to check value using breakpoint.. can u tell me that way?

Vulpes · Answer

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 in a separate variable (you could try a label to start with) and then pass that variable to your method using an 'ordinary' tag:

Jonathas Sucupira · Answer

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 bouvier · Answer

Vulpes.. yeahh..you're right.. with all value return "0".. :) so, do u know what is the problem?

kieky bouvier · Answer

Jonathas, thx for your replay.. your code look correct.. but it can't display "0" too... :'(

kieky bouvier · Answer

Vulpes, I try changing: ))%> and get this error : "Preprocessor directives must appear as the first non-whitespace character on a line"

Vulpes · Answer

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:

Jonathas Sucupira · Answer

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(); } }

Vulpes · Answer

It must be something to do with the 'binding' tag you're using. See if the following's any better: '))%> EDITED: To place quotes around inner tags

kieky bouvier · Answer

yes.. it just empty space... but if comment.Count() > 0, it can display total coment correctly

Vulpes · Answer

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: to: = GetCountComment(Convert.ToString(Eval("IdTopic")))%>

kieky bouvier · Answer

hi vulpes.. thanks for your replay.. your code can't dislay "0" too... :'( oh, no! it make me confused...

Vulpes · Answer

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(); }

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Answers (33)