WRITE YOUR OWN BLOG ENGINE // direct to post page to eliminate repeat posts header(”Location: post.php?post_id=$post_id&message=$message”); } } This code inserts a new comment into the database and e-mails you when a new comment is added. Stepping through the code: if (isset($_POST[”postcomment”]) != “”) { If the Post comment button has been pressed, the comment can be added to the database. $posttitle = addslashes(trim(strip_tags($_POST[”posttitle”]))); $name = addslashes(trim(strip_tags($_POST[”name”]))); $email = addslashes(trim(strip_tags($_POST[”email”]))); $website = addslashes(trim(strip_tags($_POST[”website”]))); $comment = addslashes(trim(strip_tags($_POST[”comment”]))); The post title (sent as a hidden field), commenter s name, e-mail address, website, and comment are all gathered from the query string and are tidied up by nesting three functions. Firstly strip_tags eliminates any HTML and PHP from the comment input, then trim removes white space (such as spaces and line breaks) from either end of the input, and finally addslashes ensures the text is formatted suitably for database entry. $sql = “INSERT INTO comments (post_id,name,email,website,comment) VALUES (’$post_id’, ‘$name’, ‘$email’, ‘$website’, ‘$comment’)”; $result2 = mysql_query($sql); if (!$result2) { $message = “Failed to insert comment.”; } else { $message = “Comment added.”; The database insert is performed. Note that the post_id is inserted with the comment so in future the blogging engine will know which comments go with which posts. $comment_id = mysql_insert_id(); As when inserting a new post, the comment_id for a new comment is automatically generated by MySQL. The latest id can be retrieved using the mysql_insert_id function. Now comes part of the script which e-mails yourself the comment so you know as soon as someone comments on your blog. PHP uses the mail function to send e-mail. An e-mail is made up of 4 four parts: the to address, the subject, the body, and the headers (which contain additional information such as the sender s details and cc d addresses). The mail function works like this: mail(to address, subject, body, headers) 315

BLOG DESIGN SOLUTIONS } ?>

Name:

Email:

Website:

Comment:

Now add the following script to the end of the PHP code (just before the closing ?> delimiter) at the top of your document: // If comment has been submitted and post exists then add comment to database if (isset($_POST[”postcomment”]) != “”) { $posttitle = addslashes(trim(strip_tags($_POST[”posttitle”]))); $name = addslashes(trim(strip_tags($_POST[”name”]))); $email = addslashes(trim(strip_tags($_POST[”email”]))); $website = addslashes(trim(strip_tags($_POST[”website”]))); $comment = addslashes(trim(strip_tags($_POST[”comment”]))); $sql = “INSERT INTO comments (post_id,name,email,website,comment) VALUES (’$post_id’, ‘$name’, ‘$email’, ‘$website’, ‘$comment’)”; $result2 = mysql_query($sql); if (!$result2) { $message = “Failed to insert comment.”; } else { $message = “Comment added.”; $comment_id = mysql_insert_id(); // Send yourself an email when a comment is successfully added $emailsubject = “Comment added to: “.$posttitle; $emailbody = “Comment on ‘”.$posttitle.”‘”.”\r\n” .”http://www.your-domain-name.com/post.php?post_id=”.$post_id . .”#c”.$comment_id.”\r\n\r\n” .$comment.”\r\n\r\n” .$name.” (”.$website.”)\r\n\r\n”; $emailbody = stripslashes($emailbody); $emailheader = “From: “.$name.” <".$email.">\r\n”.”Reply-To: ” . .$email; mail(”you@your-domain-name.com”, $emailsubject, $emailbody, . $emailheader);

WRITE YOUR OWN BLOG ENGINE Figure 7-15. Creating a new table On the next screen, input the table definition for each field, as shown in Figure 7-16. Note that for the comment_id field you should also select auto_increment in the Extra column and click the primary column. This procedure ensures that each new comment automatically gets its own unique id number. 7 Figure 7-16. Creating the comments table in phpMyAdmin Click Save and the table should be created you will see comments added to the left column. Now that you have a database table in which to store comments, you can add a form to collect comments and a script to insert to those comments into the database. Add this form to the sidebar in post.php, just after the searchform include:

BLOG DESIGN SOLUTIONS As with the edit post page in your CMS, the blog post page is called with a post_id in the query string so it knows which blog post to display. The blog homepage (index.php) you just created links to the post page like this: post.php?post_id=n where n is the post_id of a post. Clicking a link on your homepage should take you to a blog post that looks something like Figure 7-14 (if you haven t already, make sure you have added some blog posts using your CMS). Figure 7-14. The post page for your first blog post At this point, you could have a little play by adding a few new posts through your CMS and see how they appear on the homepage and on their individual post pages. Adding comments One of the great attractions of blogging is allowing your readers to comment on what you have written. I ll now show you how to add commenting to your blog engine. Each comment will be stored in the database, so first you need to create a table in which to store the comments. Open up PHPMyAdmin in your browser. Select the database blog in the left side and then click the Structure tab. In the Create new table on database blog area, type comments into the Name input box and 7 into the Number of fields input box, as shown in Figure 7-15, then click Go.

WRITE YOUR OWN BLOG ENGINE

311

BLOG DESIGN SOLUTIONS if($myposts) { echo “

\n”; do { $post_id = $myposts[”post_id”]; $title = $myposts[”title”]; echo “
• . $title

\n”; } while ($myposts = mysql_fetch_array($result)); echo “

“; } ?>