J2.5 talk:Developing a MVC Component/Adding an install-uninstall-update script file

I vote for some additional code in the preflight method, since everybody should check against a suitable version prior to install. Here is the code from the v1.6 preflight method example. I will wait for a week, before adding it to the page. Maybe there are suggestions for V2.5, that should be merged into this code, before we publish it. --gorgonz 06:05, 26 May 2012 (CDT)

First we must add some private members to the com_helloWorldInstallerScript class

        /*
         * The release value to be displayed and checked against throughout this file.
         */
        private $release = '1.0';
 
        /*
         * Find mimimum required joomla version for this extension. It will be read from the version attribute (install tag) in the manifest file
         */
        private $minimum_joomla_release = '2.5.0';

And here is the implementation

        /*
         * $parent is the class calling this method.
         * $type is the type of change (install, update or discover_install, not uninstall).
         * preflight runs before anything else and while the extracted files are in the uploaded temp folder.
         * If preflight returns false, Joomla will abort the update and undo everything already done.
         */
        function preflight( $type, $parent ) {
 
                // this component does not work with Joomla releases prior to 2.5
                // abort if the current Joomla release is older
                $jversion = new JVersion();
 
                // Extract the version number from the manifest. This will overwrite the 1.0 value set above 
                $this->release=$parent->get("manifest")->version;
 
                // Find mimimum required joomla version
                $this->minimum_joomla_release=$parent->get("manifest")->attributes()->version;    
 
                if( version_compare( $jversion->getShortVersion(), $this->minimum_joomla_release, 'lt' ) ) {
                        Jerror::raiseWarning(null, 'Cannot install com_helloWorld update in a Joomla release prior to '.$this->minimum_joomla_release);
                        return false;
                }
 
                // abort if the component being installed is not newer than the currently installed version
                if ( $type == 'update' ) {
                        $oldRelease = $this->getParam('version');
                        $rel = $oldRelease . ' to ' . $this->release;
                        if ( version_compare( $this->release, $oldRelease, 'le' ) ) {
                                Jerror::raiseWarning(null, 'Incorrect version sequence. Cannot upgrade ' . $rel);
                                return false;
                        }
                }
                else { $rel = $this->release; }
 
                echo '<p>' . JText::_('COM_HELLOWORLD_UPDATE_PREFLIGHT_' . $type . ' ' . $rel) . '</p>';
        }