{"id":11635,"date":"2009-07-13T14:01:48","date_gmt":"2009-07-13T12:01:48","guid":{"rendered":"https:\/\/mamchenkov.net\/blog\/?p=200"},"modified":"2010-03-21T17:28:05","modified_gmt":"2010-03-21T15:28:05","slug":"building-a-classified-ads-directory-with-wordpress","status":"publish","type":"post","link":"https:\/\/mamchenkov.net\/wordpress\/2009\/07\/13\/building-a-classified-ads-directory-with-wordpress\/","title":{"rendered":"Building a classified ads directory with WordPress"},"content":{"rendered":"\n

When talking about what else WordPress could be used for except blogs, classified ads directories come up high on the list.\u00a0 It’s one of those examples which illustrate the scenario nicely and doesn’t require a lot of work.<\/p>\n

So, how can WordPress be used to build a classified ads directory?\u00a0 Here is a list of a few ways you might go:<\/p>\n

    \n
  1. Buy and install ClassiPress<\/a> – a theme and plugin to do just that – build a classified ads directory.\u00a0 This is probably the fastest, cheapest, and simplest option.\u00a0 If you want one of those directories up and running within a few minutes, that’s the way to go.<\/li>\n
  2. Install wp-classified plugin<\/a> and tweak it until you are happy.\u00a0 You’ll pay with your time, not your money.\u00a0 And you won’t have to start from scratch.<\/li>\n
  3. Build your own, from scratch.\u00a0 This is suitable for those who want to have 100% understanding of how their directory works, and for those who want learn how WordPress can be customized beyond blogging.<\/li>\n<\/ol>\n

    In this post, I’ll focus only on the third option.<\/p>\n

    <\/p>\n

    So, before we start building something, it’s good to get a better idea of what is that we are actually about to build.\u00a0 Here are the things that I think a reasonable classified ads directory should have:<\/p>\n

      \n
    1. Multiple categories for ads<\/strong> (cars, electronics, books, etc.).\u00a0 Ideally, each ad should be in one category only, but we are not going to force that limitation for now.<\/li>\n
    2. Search<\/strong>.\u00a0 Categories are good, but we should be able to just type whatever is that we are looking for and find it.<\/li>\n
    3. User submitted ads, with some moderation<\/strong>.\u00a0 SPAM bots will probably be all over this, so we need some protection, without making it too hard for legitimate users.<\/li>\n
    4. Notification system for new ads<\/strong> – RSS feeds, email notifications, Twitter updates, or any combination of these.<\/li>\n
    5. Content rich, template ads<\/strong>.\u00a0 So that we can have pictures associated with ads, as well as custom data.\u00a0 For example, for cars we could ask about manual or automatic gearbox, etc.<\/li>\n<\/ol>\n

      There are of course a gadzillion of other things that we can add, but the point is to demonstrate WordPress-based problem solving within realistic scenarios, not to build a perfect classified ads directory.<\/p>\n

      Now that we know what we want (not to be confused with what women want), how can we build it?\u00a0 From the top of my head, I can suggest three possible directions:<\/p>\n

        \n
      1. Completely customized solution within WordPress.\u00a0 That would probably be packaged as a plugin, which creates and populates its own database tables, has its own administration interface, and such.<\/li>\n
      2. Re-use WordPress comments.<\/li>\n
      3. Re-use WordPress posts and post by email functionality.<\/li>\n<\/ol>\n

        Option 1 will require us to build a lot of stuff from scratch.\u00a0 The good things about this approach is that we can have a high degree of fine-tuning. For example, in such a system, we’d have custom tables to hold our ads, with very specific fields that we want.\u00a0 And we can have really specific administration interface.\u00a0 On the WordPress side, we’d probably reuse user permissions, friendly URLs, and plugin architecture (installation, upgrade, initialization, options, etc).\u00a0 The downside of this approach is the same – a lot of development.\u00a0 It will take some time to write all that code and fit it into WordPress.\u00a0 Then debug and maintain it.\u00a0 And then solve all the problems that will arise, like SPAM control and moderation of ads.\u00a0 While it can work, it’s not what I’d go for.<\/p>\n

        Option 2 is based around WordPress comments.\u00a0 We can create an empty post for each ad category that we want (cars, books, electronics, etc).\u00a0 Then a customized comment form could be used to submit ads to the specific category.\u00a0 The pros of this approach are: very little coding to be done (most of it is already there), moderation system is built-in and SPAM control can be handled by plugins like Akismet.\u00a0 Additional benefits include Gravatar support, and threads, which could be used as comments to ads (first level \/ parent comments).\u00a0 Also the RSS feeds are there.\u00a0 And even search problem could be solved with one of those enhanced search plugins.\u00a0 Rich content is also not a big problem with advanced editor plugins.\u00a0 In the cons, I’d specify flexibility.\u00a0 Since there are only so many things that you can do with comments.<\/p>\n

        Option 3 is based on WordPress posts.\u00a0 We’ll have regular categories like in the blog, and each ad would be a separate post.\u00a0 We can extend the post_type field in wp_posts table with pretty much anything we want, which would give us the control of custom fields for different ad types (fields for cars are different from fields for electronics).\u00a0 Search is ready.\u00a0 As are RSS feeds.\u00a0 And integration with notification emails, Twitter updates, etc. is trivial.\u00a0 Just install any of the plugins that broadcasts your posts and you are done.\u00a0 Figuring out the user submission and moderation processes might take some time, but with posts being more flexible (IMHO) than comments, it seems There Is More Than One Way To Do It.\u00a0 That’s a Perl motto if you didn’t know.<\/p>\n

        One of the ways to submit user content with SPAM filtering and pre-moderation might be via post by email functionality available in WordPress.\u00a0 The idea is the following.\u00a0 We create a new POP3 mailbox for those incoming ads.\u00a0 Ideally, we should probably open Gmail account, as it both supports POP3 and has excellent SPAM filtering.\u00a0 Once the POP3 account is working, we can configure WordPress post by email options.\u00a0 We’d want a separate category for these incoming messages (“new”, “incoming”, “to-moderate”) or something like that. Not one of the categories that we feature on the front page (“cars”, “books”, “electronics”, etc).\u00a0\u00a0 Once this is done, we can install one of those Contact Form plugins which helps to configure a form for site visitors and sends submitted results by email.\u00a0 In the destination mailbox we need to put the POP3 mailbox.\u00a0 Additional bonus: most of the Contact Form plugins have some sort of SPAM filtering capabilities as well.\u00a0 So we’d be protected both by the form plugin and POP3 SPAM filtering system.<\/p>\n

        As you might have guessed, Option 3 is my favourite direction.\u00a0 It seems more natural to handle ads as posts than anything else.\u00a0 And if I were to build a classifieds ads directory, that would probably be the approach that I’d take.<\/p>\n

        Let’s see if I can pull it off.\u00a0 So, the implementation plan so far is:<\/p>\n

          \n
        1. Create a new POP3 mailbox with some SPAM filtering (Gmail to the rescue).<\/li>\n
        2. Install fresh WordPress (not required, but since I don’t have anything else to play with I’ll go for that).<\/li>\n
        3. Configure posting by email in WordPress via the POP3 account created in step 1.<\/li>\n
        4. Install some Contact Form plugin that can send submitted results to email. Set it to use the POP3 account from step 1.<\/li>\n
        5. Create a page with the contact form.<\/li>\n
        6. Create categories for ads (cars, books, electronics).<\/li>\n
        7. Create a custom theme (very basic, for the sake of the example) to display ads from difference categories, and show the search form as well.<\/li>\n
        8. Submit some ads via contact form in page created by step 5.<\/li>\n
        9. Moderate the incoming ads from step 8 to approve some and decline the others.<\/li>\n
        10. Summarize the experience, provide useful links, ???, PROFIT<\/strong>.<\/li>\n<\/ol>\n

          Let’s go!<\/p>\n

          Step 1<\/strong>.<\/p>\n

          Creating a new Gmail mailbox is as easy as installing WordPress these days.\u00a0 Make sure that you follow WordPress recommendation (from the Post via e-mail<\/em> section of the Writing<\/em> administration screen):<\/p>\n

          To post to WordPress by e-mail you must set up a secret e-mail account with POP3 access. Any mail received at this address will be posted, so it\u2019s a good idea to keep this address very secret.<\/p><\/blockquote>\n

          to Once registered, you need to go to Settings<\/em>, Fowarding and POP\/IMAP<\/em>, and in POP Downloads<\/em> section Enable POP for all mail<\/em>.<\/p>\n

          Step 2<\/strong>.<\/p>\n

          Installing a new WordPress is trivial.\u00a0 Download<\/a> the archive, unzip into the folder where web server can see it, create a new MySQL database, copy wp-config-sample.php<\/em> file to wp-config.php<\/em> and update it with the location and credentials of that database.\u00a0 Now visit the the URL of your new WordPress site and finish the installation by specifying the blog title and admin email, and changing random password of administrator account to something that you can actually remember.\u00a0 Done.<\/p>\n

          Step 3<\/strong>. Configuration of POP3 access in WordPress turned out to be a bit trickier than I expected, but I managed to get through anyway.\u00a0 By default, WordPress suggests the plain-text POP3 connection (port 110).\u00a0 However, Gmail insists on encrypted connection (port 995), which is better, because it is more secure. Just changing the port in configuration didn’t help.\u00a0 But once I stumbled upon this thread in WordPress Ideas<\/a>, everything started to fall into place.\u00a0 My problem was that in Mail Server<\/em> field I had pop.gmail.com<\/em> .\u00a0 When I changed that to ssl:\/\/pop.gmail.com<\/em> (with port still set to 995), it worked liked a charm.<\/p>\n

          One thing that you would probably be confused about after setting up the above is how to actually tell WordPress to import messages from the POP3 account.\u00a0 It doesn’t do it automatically.\u00a0 To force it, you’ll need to visit yourdomain.com\/path\/to\/your\/wordpress\/wp-mail.php<\/em> .\u00a0 And since we are all about automation, I suggest that you tell your scheduler to fetch this page automatically every few minutes (“\/usr\/bin\/wget -O \/dev\/null -q URL<\/em>“, or something like that).<\/p>\n

          I also recommend to create a separate category, like “Moderatorial”, where all posts from email will go.\u00a0 When doing approvals, we’ll remove them from this category and place in the appropriate ad category.<\/p>\n

          If you did everything right and all stars aligned properly, your WordPress will now import emails from that POP3 account into your blog.\u00a0 Try sending a few emails to that secret account of yours and see.\u00a0 Also, try sending emails from several different emails there.\u00a0 You might notice that something cool is happening.\u00a0 Looking through wp-mail.php source code, I noticed that WordPress does the following check:<\/p>\n