Smart Search plug-ins are gathered together for convenience into a plug-in group called "finder". Take a look in the plugins/finder directory and you will see the plug-ins that support the core Joomla content types. It is best to create your own plug-in by taking a copy of one of these plug-ins and adapting it to meet your specific needs.
All Smart Search plug-ins extend the FinderIndexerAdapter class which contains a good many methods to deal with maintaining the index. For the vast majority of custom content requirements you will only need to override a few of these methods.
There is some additional information on writing a Smart Search plug-in here.
The principal properties
Before looking at the methods, there are a few properties that need to be set up correctly:
- This should be a unique identifier for the plug-in and establishes the context that the plug-in will respond to (eg. "Content").
- The name of the extension (component) that handles the content type (eg. "com_content").
- The sublayout to use when rendering search results. For example, of $layout is set to "article" then the default view will look for a layout file called default_article.php when it needs to render a search result of this type. If no such file is found then the layout file called default_result.php will be used instead.
- The name of the table to retrieve data from (eg. "#__content").
- The database field in your table that the published state of an item is stored in; default's to "state".
The principal methods
The first methods you will want to override when developing a new Smart Search plug-in are the setup, index and getListQuery methods. In the vast majority of cases those three methods will be enough to get your content indexed, although the plug-in will not be complete as there are other methods that must be implemented to deal with issues such as updating the index when the content changes. But those three methods are the working core of the plug-in.
- This method is called by the indexer once before an indexing run begins. It can be used to load libraries or initialise variables for the plug-in. Must return true.
- This is the main method called by the indexer. It is called once for each content item that is to be indexed (or the index updated). The index method essentially describes the content to the indexer by telling the indexer which fields to parse for terms/phrases and their relative weights, which fields to map into branches of the content map and what data to include in the index as "payload". This method is described in more detail later.
- This method must return a JDatabaseQuery object that will form the basis of a query that will return a list of objects of the given content type. There are constraints on this query to ensure that it is compatible with other methods used by the indexer. This method is described in more detail later.
Some other methods
For a complete Smart Search plug-in there are a number of other methods you may need to override.
- Given a content item this method translates the native state of the content item into a state that the indexer can use. It must return an integer 0 if the content item is not to appear in search results, or an integer 1 if the content item can appear in search results.
- Returns the non-SEF URL for an item. The default return, using plg_finder_content for example, is 'index.php?option=com_content&view=article&id=1'.
- This method is used to build a generic query for checking the access and state of items and their parent categories. This method uses the $table and $state_field properties to select the correct data.
The following methods are called via the Smart Search content plug-in in response to specific trigger events in Joomla.
- Called in response to an onContentBeforeSave event.
- Called in response to an onContentAfterSave event.
- Called in response to an onContentDelete event.
- Called in response to an onContentChangeState event.
- Called in response to an onCategoryChangeState event.
Methods in more details
This method must return a JDatabaseQuery object that will form the basis of a query that will return a list of objects of the given content type. There are constraints on this query to ensure that it is compatible with other methods used by the indexer. If the following conditions are not true then you will need to override other methods in the FinderIndexerAdapter class.
- The primary database table that is being indexed must have an alias of "a".
This method is called whenever a content item needs to be indexed (or re-indexed). It is passed an object of type FinderIndexerResult and its purpose is to make adjustments to that object and to add metadata before handing control to FinderIndexer::index method to do the indexing proper.
This method is called prior to the index method and is used to set up the index process. In this method is where you would typically include any externally required classes to allow for proper indexing.
- extension (only used in core for com_categories plugin)
Testing a finder plugin can be a bit difficult due to the fact that it is typically run using an ajax process, so you don't tend to actually see any results from the process.
As such, one way to test is to use the command line indexer.
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