I need some help on this php problem.

major dynamic123 · March 3rd, 2004, 09:36 PM

Hi. I'm Major. I hope someone here can help me out with this problem. I am developing a shopping cart for my bookstore. I am trying to pass some variables(isbn, title, price) from bookdetails.php to showcart.php.

The problem is when I pass the variable(from bookdetails.php) and use the $_GET function(at showcart.php), it shows me the variable name, and not the variable value. I have tried various ways to get the variable to the next page; showcart.php, but failed.

I hope someone in this forum can help me out with this problem.

Thanks.

Regards,
Major

Below is the source code for bookdetails.php
=============================================
<html>
<head>
<title>Book Detail</title>
<link rel="stylesheet" href="fontlib.css" style="text/css">
</head>

<body>
<style>

</style>

<body background="#ffffff" topmargin=0 leftmargin=0 marginwidth=0 marginheight=0>

<table border=0 width=100% height=10 cellspacing=0 cellpadding=0 bgcolor=#8FBC8F>
 <tr><td> 
 <img src="./picturefiles/company_logo.jpg" border=1 align=center>  ikhtiar-resources.com 
 </td>
 </tr>
</table>

<table border=0 width=100% height=10 cellspacing=0 cellpadding=0 bgcolor=black>
 <tr><td align=right>
 <img src="./picturefiles/bluebullet.gif" align=center> <a href="index.php">Home</a> 
 <img src="./picturefiles/bluebullet.gif" align=center> <a href="books.php">Books</a> 
 <img src="./picturefiles/bluebullet.gif" align=center> <a href="faq.php">FAQ</a> 
 <img src="./picturefiles/bluebullet.gif" align=center> <a href="help.php">Help</a> 
 <img src="./picturefiles/bluebullet.gif" align=center> <a href="emailus.php">Email Us</a> 
 <img src="./picturefiles/bluebullet.gif" align=center> <a href="search.php">Search 
 </td>
 </tr>
</table>

[list]<img src="./picturefiles/previousbluearrow.gif" align=center><a href="javascript:history.back()">[u]Previous Page</a>
 | 
<a href="javascript:history.forward()">[u]Next Page</a><img src="./picturefiles/nextbluearrow.gif" align=center></ul>

 
<?php
 echo '[list]';

 $bookdetail = $HTTP_GET_VARS['id'];
 include("./exc/psal.inc");

 $query_bookdetail = "select
 b_covers.isbn_cover, b_covers.price,
 b_covers.fk_cover_id,
 b_cats.isbn_category, b_cats.title,
 bs.book_isbn, bs.book_author,
 bs.book_description, bs.book_url,
 bs.book_misc, bs.book_pages,
 bs.fk_publisher_id, c.cover, mp.mth_id,
 mp.mth, yp.yr_id, yp.yr, p.publisher_id,
 p.publisher_name

 from books bs, books_categories b_cats,
 books_covers b_covers, covers c,
 mth_published mp, yr_published yp,
 publishers p

 where bs.book_isbn='$bookdetail' and
 b_covers.isbn_cover = '$bookdetail' and
 b_cats.isbn_category = '$bookdetail' and
 c.cover_id = b_covers.fk_cover_id and
 bs.fk_mth_id = mp.mth_id and
 bs.fk_yr_id = yp.yr_id and
 bs.fk_publisher_id = p.publisher_id";

 $result_bookdetail = mysql_query($query_bookdetail) or die("Error in query");
 $num_result_bookdetail = mysql_num_rows($result_bookdetail);

 if (mysql_num_rows($result_bookdetail) > 0) {
 while($row = mysql_fetch_object($result_bookdetail)) { ?>
 <? echo '<table border=0 bgcolor=#ffffff width=80%' ?>
 <? echo '<tr>' ?>
 <? echo '<td colspan=2>'
 .$row->title. ' </td>'; ?>
 <? echo '</tr>' ?>

 <? echo '<tr>' ?>
 <? echo '<td>' ?>
 <img src="<? echo $row->book_url; ?>" border=1>
 <? echo '</td>' ?>
 <? echo '<td valign=top>' ?>
 <? echo 'ISBN: '
 .$row->book_isbn. ''?>
 <? echo ' ' ?>
 <? echo 'Author:
 ' .$row->book_author. '' ?>
 <? echo ' ' ?>
 <? echo 'Pages:
 ' .$row->book_pages. ' pages.' ?>
 <? echo ' ' ?>
 <? echo 'Cover:
 ' .$row->cover. '' ?>
 <? echo ' ' ?>
 <? echo 'Published by:
 ' .$row->publisher_name. '' ?>
 <? echo ' ' ?>
 <? echo 'Date Published:
 ' .$row->mth. ', ' ?>
 <? echo ''
 .$row->yr. '' ?>
 <? echo ' ' ?>
 <? echo 'Price(RM):
 ' .$row->price. '' ?>
 <? echo '(Price is subject
 to change without prior notice)'?>
 <? echo ' ' ?>

// Here's where the problem is. I am trying to pass the variable's
// value from $row->book_isbn to $id.

 <? $isbn = $row->book_isbn; $id=$isbn; ?>
 <? echo $isbn; ?>
 <? echo '<a href="showcart.php?id=
 <? echo $id ?>">Add to cart</a>'; ?>
 <? echo '</td>' ?>
 <? echo '</tr>' ?>
 <? echo '</table>' ?>

 <? echo ' ' ?>
 <? echo '<table border=0 bgcolor=#ffffff width=80%>' ?>
 <? echo '<tr>' ?>
 <? echo '<td>' ?>
 <? echo '' ?>
 <? echo '
 [u]Description ' ?>
 <? echo ''
 .nl2br($row->book_description). '' ?>
 <? echo '</td>' ?>
 <? echo '</tr>' ?>
 <? echo '</table>' ?>
 <? }
 }

 mysql_close($connection);
 echo '</ul>';
?>

</body>
</html>

Below is the source code for showcart.php
=========================================
<html>
<head><title>showcart</title></head>

<body>

// Inside here, no value is printed out. Instead it prints $id on
// the screen.

<?php
 $isbn = $HTTP_GET_VARS['id'];

 echo $isbn;

?>

</body>
</html>

Snib · March 3rd, 2004, 09:58 PM

I don't know if this will help you or not, but HTTP_*_VARS is no longer in use (unless you're using a very old version, which you really shouldn't be :))

Use $_GET[]

Gotta go,

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major dynamic123 · March 3rd, 2004, 10:37 PM

No, the $_GET method didn't work for me. I tried that before this.

regards,
major

nikolai · March 4th, 2004, 06:05 PM

I didn't see anywhere in your code where you actually SET id in a URL parameter. You try to set it here:

Quote:

quote:
 <? $isbn = $row->book_isbn; $id=$isbn; ?>
 <? echo $isbn; ?>
 <? echo '<a href="showcart.php?id=
 <? echo $id ?>">Add to cart</a>'; ?>
 <? echo '</td>' ?>

But that won't work. You open a single quoted string, and echo everything up to the closing single quote mark.

Try this:

 echo "<a href=\"showcart.php?id={$id}\">Add to cart</a>";

See the difference? Your version would also work if you terminated your single-quoted string as follows:

 <? $isbn = $row->book_isbn; $id=$isbn; ?>
 <? echo $isbn; ?>
 <? echo '<a href="showcart.php?id='; ?>
 <? echo $id ?>
 <? echo '">Add to cart</a>'; ?>
 <? echo '</td>' ?>

I can't help but mention that your code is kinda sloppy... you enter and leave PHP blocks wayyyy too frequently (for my taste). In this case, it was your undoing.

What about using just ONE code block? For example:

<?php

 if (mysql_num_rows($result_bookdetail) > 0)
 {
 while ($row = mysql_fetch_object($result_bookdetail))
 {
 echo "<table border=0 bgcolor=#ffffff width=80%>"\n;
 echo " <tr>\n";
 echo ' <td colspan=2>'
 . $row->title
 . " </td>\n";

 etc..

?>

Take care,

Nik
http://www.bigaction.org/

major dynamic123 · March 5th, 2004, 04:16 AM

Hi, Nikolai. Thanks for your help. And thanks for mentioning about the repeating php blocks. Well, I am still learning how to do PHP myself.

I do not understand the "\" symbol. Can you explain to me what ie means? and the {} symbol too.

echo "<a href=\"showcart.php?id={$id}\">Add to cart</a>";

regards,
major

Snib · March 5th, 2004, 05:42 PM

The "\" indicates an escape:

http://www.php.net/types.string

echo "this " is bad because PHP thinks you ended the string there";

echo "this \" is good because PHP knows that it needs to PRINT the quote instead of using it as the end of the string";

I'm looking into the "{}", perhaps Nik can help you...

I'll let you know if I find out.

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---Snib---
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Snib · March 5th, 2004, 05:49 PM

Ah, I found it.

Same page about the strings, a little ways down (use find(on this page) for "braces").

PHP uses the {} to separate variables from text.

Code:

// if the variable is $page

echo "these web $pages are great"; // PHP thinks it is a variable called $pages
echo "these web {$page}s are great"; // PHP knows $page is the variable
echo "these web " . $page . "s are great"; // this also works, although it is a little longer

I hope I have helped you,

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