Overview

An RSS feed is an XML format that is great for sharing and broadcasting content such as news, articles, events, etc. There are a number of feed readers (or “aggregators”) available for users to access multiple RSS feeds from one location. Most modern web browsers support RSS feeds, as well.

Inside every RSS feed there are at least two elements: channel, which provides information about the feed itself, and one or more items, which provide information about the content the feed represents.

If you have a blog or some other kind of publishing system, chances are it uses a database. With the Dynamic RSS PHP class, you can easily add an RSS feed using the information that’s stored in your MySQL database. Here’s a sample of what the code looks like. It may appear intimidating at first, but it’s actually quite easy. I’ll go over everything right after the example.

<?php

include("DynamicRSS.class.php");

$rss = new DynamicRSS();
$rss->db('localhost', 'dbname', 'dbuser', 'dbpass')
    ->query("
        SELECT id,
        title,
        CONCAT(email, ' (', author, ')') as author,
        article,
        DATE_FORMAT(article_date, '%a, %d %b %Y %H:%i:%s EST') as pubDate,
        'http://example.com/article?id={{id}}' as link
        FROM articles
        ORDER BY article_date DESC
        LIMIT 10
    ")
    ->channel( array(
        'title'=>'Example RSS Feed',
        'link'=>'http://example.com/',
        'description'=>'The best RSS feed you will ever encounter',
        'language'=>'en-us',
        'copyright'=>'Copyright 2008 Example.com',
        'managingEditor'=>'editor@example.com (Editor Name)',
        'ttl'=>60
    ))
    ->image('http://example.com/images/logo.png', 200, 100)
    ->item( array(
        'title'=>'title',
        'link'=>'link',
        'author'=>'author',
        'description'=>'article',
        'guid'=>'link',
        'pubDate'=>'pubDate'
    ))
    ->generate();

?>

Implementing the DynamicRSS class

The DynamicRSS class supports method chaining, which makes it possible to generate your RSS feed in just two PHP statements. The first statement simply creates the DynamicRSS object. Let’s take a look at the methods being used in the second statement.

1. The db() method is used to setup a connection to your database.
2. The query() method defines the query that will pull information from your database
3. The channel() method defines information about your feed
4. The image() method lets you associate an image with your feed
5. The item() method defines information about the feed’s content
6. The generate() method produces the feed

Hopefully, that breakdown makes it seem a bit easier. Now, let’s look at a few specifics.

Creating Your Query

To the query() method, I’m passing a MySQL statement that will pull the 10 most recent articles from my database. The fields returned by this query will be used to generate items in the feed, so it’s important that they are formatted properly. For a valid RSS feed, the author field (and any other field requiring an email address) should be formatted as author@example.com (Author’s Name). In this case, since the email and the author’s name are stored in two separate fields, I’m using the CONCAT() function to produce the appropriate format:

CONCAT(email, ' (', author, ')') as author

You might also notice that I’m doing something strange with the publication date:

DATE_FORMAT(article_date, '%a, %d %b %Y %H:%i:%s EST') as pubDate

This simply formats a MySQL datetime field as an RFC 822 compliant date/time representation, which is required by the RSS 2.0 standard.

There’s also something strange going on with my link field:

'http://example.com/article?id={{id}}' as link

The {{id}} is referencing the id field of the same row in the same database table. This is useful because you’re going to want to link people to your articles from your RSS feed but, being dynamic and all, the page you will have to link to will change with each article. You can reference any field name in the query() method using the same curly bracket syntax described above.

Defining Your Channel

To the channel() method, I’m passing an array containing a list of element names and values that will be used in the feed. You can pass any of the valid channel elements in this array, but make sure you pass at least the title, link, and description, as those are required by the RSS 2.0 standard.

Associating an Image

The image method is optional, but when used will associate an image with your feed. The first paramter is a URL to the image. The second and third parameters are width and height, respectively.

Creating Items

To the item() method, I’m passing another array. This time, the array contains a list of elements that will be used to generate items in the RSS feed. Each array key represents the name of an item sub-element, and the corresponding value is the name of the corresponding database field to use:

array(
    'title'=>'title_field',
    'link'=>'link_field',
    'author'=>'author_field',
);

This will create each item in your RSS feed with three sub-elements:

<item>
    <title>Example Title</title>
    <link>http://example.com/article.php?id=1234</link>
    <author>John Doe</author>
</item>

Here is a list of valid item elements from the RSS 2.0 specification.

Note that each value in your array must be the name of a field in the database. But what if, for example, you are the author of all your articles and you designed your database without an author field? Simple, just fake one in your query:

SELECT id, title, 'John Doe' AS author, article_date, ...

In similar ways, you should be able to manipulate your query enough in pure SQL to accommodate your feed.

Generating the Feed

The generate() method, by default, outputs the RSS feed. This should be the very first output that occurs on the calling page, otherwise you will receive an error. Note that you can modify the output of this method by passing ‘string’ as a parameter. This will return the XML data as a string that you can store in a variable.

Method Table

Now that we’ve covered the basics, here’s a comprehensive method table that will provide some enhanced functionality for advanced users:

All of these methods can be chained as shown in the first example.

Download

Download the current version of the DynamicRSS PHP class: Version 1.0

This class is provided to you as-is, at absolutely no cost. If you would like to support its development, feel free to contribute any amount you prefer via PayPal. As always, you are welcome to contribute code for bug fixes and feature enhancements as well. Either way, thanks for supporting our efforts!

Known Issues

• Relative URLs will fire a warning in the feed validator. It is preferred to use absolute URLs in all of your articles for best compatibility with feed reading devices.
• The class currently uses htmlentities() to encode special characters. This function will not invalidate a feed, but it needs to be replaced with a similar xmlentities() function for optimal compatibility.

Please report any bugs you find using our contact form.

Resources

• Official RSS 2.0 documentation
• Required Channel Elements
• Optional Channel Elements
• Item Elements
• Atom and RSS FEED Validator

Licensing

This software is licensed under the GNU General Public License.