PHP tutorial: Blog (including commenting)
Posted: Tue Feb 19, 2013 10:26 am
I nearly have everything working except for new comment submissions. When I run the blog_read.php file I get an error message that we defined ourselves in the tutorial "Invalid Post ID." I have been troubleshooting for quite a while already and haven't come up with anything relating to this issue. My code matches the videos' exactly. Any help will be appreciated greatly as I am new to this and need a little nudge in the right direction. Cheers!
blog_read.php
blog_read.php
<?php
include('core2/init.inc.php');
if (isset($_GET['pid'], $_POST['user'], $_POST['body'])) {
if (add_comment($_GET['pid'], $_POST['user'], $_POST['body'])) {
header("Location: blog_read.php?pid={$_GET['pid']}");
}else {
header('Location: blog_list.php');
}
die();
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Blog Tutorial</title>
</head>
<body>
<div>
<?php
if (!isset($_GET['pid']) || valid_pid($_GET['pid']) !== true) {
echo 'Invalid post ID.';
} else {
$post = get_post($_GET['pid']);
?>
<h2><?php echo $post['title']; ?></h2>
<h4>By <?php echo $post['user']; ?> on <?php echo $post['date']; ?> (<?php echo count($post['comments']); ?> comments)</h4>
<hr />
<p><?php echo $post['body']; ?></p>
<hr />
<?php
foreach ($post['comments'] as $comment) {
?>
<h4>By <?php echo $comment['user']; ?> on <?php echo $comment['date']; ?></h4>
<p><?php echo $comment['body']; ?></p>
<hr />
<?php
}
?>
<form action="blog_read.php" method="POST">
<p>
<label for="user">Name</label>
<input type="text" name="user" id="user" maxlength="50" />
</p>
<p>
<textarea name="body" rows="20" cols="60"></textarea>
</p>
<p>
<input type="submit" value="Add Comment" />
</p>
</form>
<?php
}
?>
</div>
</body>
</html>
blog_post.php
<?php
include('core2/init.inc.php');
if (isset($_POST['user'], $_POST['title'], $_POST['body'])) {
add_post($_POST['user'], $_POST['title'], $_POST['body']);
header('Location: blog_list.php');
die();
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Blog</title>
</head>
<body>
<form action="" method="POST">
<p>
<label for="user">Name</label>
<input type="text" name="user" id="user" />
</p>
<p>
<label for="title">Title</label>
<input type="text" name="title" id="title" />
</p>
<p>
<textarea name="body" rows="20" cols="60"></textarea>
</p>
<p>
<input type="submit" value="Add Post" />
</p>
</form>
</body>
</html>
blog_list.php
<?php
include('core2/init.inc.php');
?>
<!DOCTYPE html>
<html lan="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>PHP Blog</title>
</head>
<body>
<div>
<?php
$posts = get_posts();
foreach ($posts as $post) {
?>
<h2><a href="blog_read.php?pid=<?php echo $post['id']; ?>"><?php echo $post['title']; ?></a></h2>
<h4>By <?php echo $post['user']; ?> on <?php echo $post['date']; ?></h4>
<h4>(<?php echo $post['total_comments']; ?> comments, last comment posted: <?php echo $post['last_comment']; ?>)</h4>
<hr />
<p><?php echo $post['preview']; ?></p>
<?php
}
?>
</div>
</body>
</html>
post.inc.php
<?php
//checks if the given post id is in the table.
function valid_pid($pid) {
$pid = (int)$pid; //making this an integer drops everything that isn't a number and helps prevent sql injection.
$total = mysql_query("SELECT COUNT(`post_id`) FROM `posts` WHERE `post_id` = {$pid}"); //COUNT counts the number of rows in the results and returns that in a single cell.
$total = mysql_result($total, 0);
if ($total != 1) {
return false;
} else{
return true;
}
}
//fetches a summary of all the blog posts.
function get_posts () {
$sql = "SELECT
`posts`.`post_id` AS `id`,
`posts`.`post_title` AS `title`,
LEFT(`posts`.`post_body`, 512) AS `preview`,
`posts`.`post_user` AS `user`,
DATE_FORMAT(`posts`.`post_date`, '%d/%m/%Y @ %H:%i:%s') AS `date`,
`comments`.`total_comments`,
DATE_FORMAT(`comments`.`last_comment`, '%d/%m/%Y @ %H:%i:%s') AS `last_comment`
FROM `posts`
LEFT JOIN (
SELECT
`post_id`,
COUNT(`comment_id`) AS `total_comments`,
MAX(`comment_date`) AS `last_comment`
FROM `comments`
GROUP BY `post_id`
) AS `comments`
ON `posts`.`post_id` = `comments`.`post_id`
ORDER BY `posts`.`post_date` DESC";
$posts = mysql_query($sql);
$rows = array();
while (($row = mysql_fetch_assoc($posts)) !== false) {
$rows[] = array(
'id' => $row['id'],
'title' => $row['title'],
'preview' => $row['preview'],
'user' => $row['user'],
'date' => $row['date'],
'total_comments' => ($row['total_comments'] === null) ? 0 : $row['total_comments'],
'last_comment' => ($row['last_comment'] === null) ? 'never' : $row['last_comment']
);
}
return $rows;
}
//fetches a single post from the table.
function get_post($pid) {
$pid = (int)$pid;
$sql = "SELECT
`post_title` AS `title`,
`post_body` AS `body`,
`post_user` AS `user`,
`post_date` AS `date`
FROM `posts`
WHERE `post_id` = {$pid}";
$post = mysql_query($sql);
$post = mysql_fetch_assoc($post);
$post['comments'] = get_comments($pid);
return $post;
}
//adds a new blog entry.
function add_post($name, $title, $body) {
$name = mysql_real_escape_string(htmlentities($name));
$title = mysql_real_escape_string(htmlentities($title));
$body = mysql_real_escape_string(nl2br(htmlentities($body))); //nl2br() convert any new lines into line break tags. mysql_real_escape_string() escapes new lines, so that is why we add the nl1br() function inside it.
mysql_query("INSERT INTO `posts` (`post_user`, `post_title`, `post_body`, `post_date`) VALUES ('{$name}', '{$title}', '{$body}', NOW())");
}
mysql_error();
?>
comment.inc.php
<?php
//fetches all of the comments for a given blog post.
function get_comments($pid) {
$pid = (int)$pid;
$sql = "SELECT
`comment_body` AS `body`,
`comment_user` AS `user`,
DATE_FORMAT(`comment_date`, '%d/%m/%Y @ %H:%i:%s') AS `date`
FROM `comments`
WHERE `post_id` = {$pid}";
$comments = mysql_query($sql);
$return = array();
while (($row = mysql_fetch_assoc($comments)) !== false) {
$return[] = $row;
}
return $return;
}
//adds a comment.
function add_comment($pid, $user, $body) {
if (valid_pid($pid) === false) {
return false;
}
$pid = (int)$pid;
$user = mysql_real_escape_string(htmlentities($user));
$body = mysql_real_escape_string(nl2br(htmlentities($body)));
mysql_query("INSERT INTO `comments` (`post_id`, `comment_user`, `comment_body`, `comment_date`) VALUES ({$pid}, '{$user}', '{$body}', NOW())");
return true;
}
?>
init.inc.php
<?php
error_reporting(E_ALL);
mysql_connect('127.0.0.1', 'xxxx', 'xxxx');
mysql_select_db('blog');
require('inc/comment.inc.php');
require('inc/posts.inc.php');
?>