Automatic Updates For Private And Commercial Plugins

Last updated on May 17, 2014.

Since time immemorial, only plugins hosted in the official WordPress.org plugin directory have supported automatic updates. Now, I’ve written a PHP library that you can use to add automatic update capabilities to any plugin. Public, private and commercial plugins alike – all can now enjoy the benefits of automatic update notifications and one-click upgrades.

The custom update checker integrates closely with the upgrade system already built into WordPress, producing a seamless user experience. Observe :

An upgrade notice for a privately hosted plugin.

The ‘Plugin Information’ window with placeholder data.

Download

License




This library is licensed under the GPL and is distributed free of charge. If you find it useful, consider making a donation.

Commercial licensing (e.g. for projects that can’t use an open-source license) is available upon request.

Quick-start Guide

This section describes the quickest way to get automatic updates working for your plugin. Here’s what you’ll need to do: create a metadata file for your plugin, host it somewhere publicly accessible, and tell the update checker where to find it.

Lets start with the metadata. Copy the JSON code below into a new file and replace the placeholder values with your plugin’s info.

{
    "name" : "My Cool Plugin",
    "slug" : "my-cool-plugin",
    "download_url" : "http://example.com/plugins/my-cool-plugin.zip",
    "version" : "2.0",
    "author" : "John Smith",
    "sections" : {
        "description" : "Plugin description here. Basic HTML allowed."
    }
}

(This is the minimal amount data required to make automatic updates work. In most cases, you will probably want to add a couple more fields. See the metadata docs below for details.)

Most of the fields should be pretty self-explanatory, with one possible exception – the “slug”. WordPress expects all plugins that support automatic updates to have a unique textual identifier called the “slug”. Normally, slugs are assigned by the official plugin directory. For a private/commercial plugin that’s hosted elsewhere you’ll have to make something up. If unsure, just use the plugin’s file name without the “.php” extension (my-cool-plugin/my-cool-plugin.php becomes my-cool-plugin).

Upload the metadata file you just created to your web server. It doesn’t matter where exactly you put the file or how you name it. The important thing is for its URL to be accessible from wherever someone might install your plugin.

Next, copy the “update-checker” directory from the client library archive to your plugin’s directory. Then fire up your favourite code editor and add the following lines to the top of your plugin file:

require 'plugin-updates/plugin-update-checker.php';
$MyUpdateChecker = PucFactory::buildUpdateChecker(
    'http://example.com/path/to/metadata.json',
    __FILE__,
    'your-chosen-slug'
);

If you followed my advice and used the plugin’s file name as the slug, you can omit the third parameter of the PucFactory::buildUpdateChecker() call.

Tip: Sometimes you’ll run into a situation where another active plugin is also using this update checker. As a result, there could be several different versions of the library loaded at the same time. The above code snippet will always give you the latest available version. This can be a problem if your plugin expects an older version and is not API-compatible with the latest version.

To use a specific version of the update checker (e.g. the one included with your plugin), instantiate the PluginUpdateChecker_x_y class directly. Replace x and y with the major and minor version numbers:

//Use version 1.5 of the update checker.
require 'plugin-updates/plugin-update-checker.php';
$MyUpdateChecker = new PluginUpdateChecker_1_5 (
    'http://example.com/path/to/metadata.json',
    __FILE__,
    'your-chosen-slug'
);

And that, believe it or not, is it.

The PluginUpdateChecker class will handle the rest. It’ll check the metadata file every 12 hours and, if it discovers that a new version has been released, twiddle the right bits in the undocumented WP API to make it show up as a standard upgrade notification in the “Plugins” tab. Assuming you’ve set up the download_url correctly, users will be able to install the update with a single click.

The rest of this post will be devoted to a more in-depth discussion of the update checker class and the metadata format.

The PluginUpdateChecker class

This class is the core of the update checker. It’s also the only part of the updater that you should need to deal with unless you decide to  extend the library yourself.

Class constructor

All configuration settings should be specified by passing them to the PucFactory::buildUpdateChecker() factory method, or directly to the PluginUpdateChecker constructor. Both takes the following parameters:

  • $metadataUrl – The full URL of the plugin’s metadata file.
  • $pluginFile – The path to the plugin’s file. In most cases you can simply use the __FILE__ constant here.
  • $slug – The plugin’s ‘slug’. If not specified, the filename part of $pluginFile (sans “.php”) will be used as the slug.
  • $checkPeriod – How often to check for updates (in hours). Defaults to checking every 12 hours. Set to zero to disable automatic update checks.
  • $optionName – Where to store book-keeping info about updates. Defaults to “external_updates-$slug”.

checkForUpdates()

Manually trigger an update check. This is especially useful when you’ve disabled automatic checks by setting $checkPeriod (above) to zero. This method takes no parameters and returns nothing.

addQueryArgFilter($callback)

Register a callback for filtering query arguments. Whenever the update checker needs to retrieve the metadata file, it will first run each filter callback and attach the query arguments that they return to the metadata URL. This lets you pass arbitrary data to the server hosting the metadata. For example, commercial plugins could use it to implement some kind of authorization scheme where only users that have the right “key” get automatic updates.

The callback function will be passed an associative array of query arguments and should return a modified array. By default, the update checker will add these arguments to the metadata URL:

  • installed_version – set to the currently installed version of the plugin.
  • checking_for_updates – set to 1 if checking for updates, absent otherwise (i.e. when loading data for the “Plugin Information” box).

This method takes one parameter – the callback function.

addHttpRequestArgFilter($callback)

Register a callback for filtering the various options passed to the built-in helper function wp_remote_get that the update checker uses to periodically download plugin metadata. The callback function should take one argument – an associative array of arguments – and return a modified array or arguments. See the WP documentation on wp_remote_get for details about what arguments are available and how they work.

This method takes one parameter – the callback function.

addResultFilter($callback)

Register a callback for filtering plugin info retrieved from the metadata URL.

The callback function should take two arguments. If the metadata was retrieved successfully, the first argument passed will be an instance of PluginInfo (see the source for a description of this class). Otherwise, it will be NULL. The second argument will be the corresponding return value of wp_remote_get (see WP docs for details). The callback function should return a new or modified instance of PluginInfo or NULL.

This method takes one parameter – the callback function.

Metadata format

The automatic update system uses a JSON-based file format to describe plugins.  Essentially, the entire file is one big JSON-encoded object (AKA hash-table or associative array). Each field – or array key – represents a piece of information about the latest version of the plugin. The full description of all available fields is here.

For the sake of simplicity, both general metadata and update-related information are stored in the same file. If this is undesirable, you can replace the plain JSON file with a script that checks for the presence of the the “checking_for_updates” query parameter and emits just the update-related fields if its set to “1″.

Notes

Your plugin must be active for updates to work. The update checker is just another piece of PHP code loaded and run by your plugin, and it won’t be run if the plugin is inactive.

One consequence of this that may not be immediately obvious is that on a multisite installation updates will only show up if the plugin is active on the main site. This is because update notifications usually appear in the network admin, and only plugins active on the main site are loaded in that case. The main site of a WordPress network is the one that was created first and has the path “/” in the Sites -> All Sites list.

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255 Responses to “Automatic Updates For Private And Commercial Plugins”

  1. Jānis Elsts says:

    When the notification is displayed, what URL do you see in the address bar? Is it the same for all plugins, or different? Normally it would be different for each plugin.

  2. Bill Phelps says:

    All 3 URLs are identical:
    http://www.chapeltowncohousing.org.uk/2012/cms/wp-admin/plugins.php?puc_update_check_result=no_update

    ie: nothing to identify which plugin is being checked.

    However, the 3 identical notifications are the correct response for whichever “Check for updates” link was clicked.

  3. Jānis Elsts says:

    It sounds like you’re using an old version of the library. Try the GitHub version.

  4. Bill Phelps says:

    Janis – Yes, that fixed it :)

    Don’t know how I ended up with the wrong one.

    Many thanks for your help!

    Bill

  5. Incredibly useful, thank you for distributing this library.

  6. Pratik says:

    Hi, is there a way to make this work for themes as well?

  7. Pratik says:

    nevermind, just saw another post in related posts :D

  8. Andrea Leti says:

    I have used this class.
    Very nice and work!

    But when update the plugin this after return Deactivate! :(

    Why?

  9. Jānis Elsts says:

    But when update the plugin this after return Deactivate! Why?

    That’s probably not directly related to this class. It could be some kind of a plugin conflict, or perhaps a configuration problem. For example, if the plugin directory name in your update ZIP file doesn’t match the original directory name, WordPress might not know how to re-activate the plugin after the update.

  10. Darren says:

    Hi,
    Any idea why after updating it’s renamed the ‘plugin-slug’ directory to ‘.tmp’?

    -d

  11. Jānis Elsts says:

    Is you .zip directory structure correct? All plugin files should be inside a “plugin-slug” directory. If they’re at the root of the archive, you can get strange results.

  12. Darren says:

    This fixed the issue, thanks for responding so quickly and for such a great script.

    cheers,
    -d

  13. Hi,

    Great module ! I have been using it for my first WP plugin and it worked great.

    My first plugin directory name was “soundy-background-music” for the free version hosted on WordPress.org and “soundy-music-pro” for the PRO version hosted on webartisan.ch. In both cases, the main file in the plugin directory was soundy.php.

    Everything worked well.

    For my second plugin, I’ve decided to use the same directory name and the same main file name for both plugins and it looks like it was not a good decision as the PRO version is taken over by WP’s default update checker and it seems that the embedding of your update checker is ignored for the PRO version.

    Is it correct ? Should the free and the PRO plugins have different directory/main file names in order to have them updated correctly from each side, WordPress.org and WebArtisan.ch ?

    Or is there a way to have the updates correctly taken over despite the same names ?

    Thanks in advance for your answer.

    Bertrand

  14. Jānis Elsts says:

    Which version of the library are you using? In theory, the latest version should overwrite the update info from wordpress.org with your Pro version info.

    In practice, I would strongly recommend giving the Pro version a different slug (directory name). Trying to hijack existing WP updates is generally a bad idea. The update checker can do it with the right configuration, but it’s not designed for that.

  15. I’m using Plugin Update Checker Library 1.5.

    I will follow your recommendation and revert to different slug names for the free and PRO versions.

    Thanks for your answer.

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