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A search module (requires Q2A 1.5+) enables plugins to create a custom index of the content in a Q2A site, including questions, answers, comments and custom pages. If a search module is selected by the site administrator, it can replace the default Q2A search results with its own, and optionally include pages from external websites in those results.

The PHP class for a search module may contain the following functions (all are optional):

  • index_post($postid, $type, $questionid, $parentid, $title, $content, $format, $text, $tagstring, $categoryid). If defined, this function is called when a post should be added to the search index, either because it is new, or because it has just been edited. The parameter $postid contains the postid from the database. The $type will be 'Q' for questions, 'A' for answers, 'C' for comments or 'NOTE' for a note (currently used for question closing explanations). The $questionid is the postid of the question to which the post belongs and the $parentid is the postid of its immediate parent, or null if it has none. For questions, $title contains the title in UTF-8 format, otherwise it is null. The $content and $format parameters describe the post's content. If $format is '', then $content contains plain text in UTF-8 encoding. If $format is 'html', then $content contains HTML with UTF-8 encoding. Other values of $format may be present if a non-standard editor module is installed. The $text parameter contains a UTF-8 plain text rendering of the post, which is particularly useful for building a search index. For questions, $tagstring contains a comma-separated list of tags, otherwise it is null. Finally, $categoryid contains the category ID of the post, or null if there is none. Note that index_post() is only called when a post has been made visible on the Q2A site - it is not called if a new post was marked for moderation.

  • unindex_post($postid). If defined, this function is called when a post should be removed from the search index, because it has been hidden, deleted, or is about to be edited (in which case index_post() will be called immediately after). Generally, the parameter $postid matches a value previously passed to index_post() when the post was indexed. However in some circumstances the $postid might never have been indexed, in which case the function should do nothing.

  • move_post($postid, $categoryid). If defined, this function is called when a post's category is changed. The parameter $postid is the post's postid from the database, and $categoryid is its new categoryid. Generally, the parameter $postid matches a value previously passed to index_post() when the post was indexed. However in some circumstances the $postid might never have been indexed, in which case the function should do nothing.

  • index_page($pageid, $request, $title, $content, $format, $text). If defined, this function is called when a custom page should be added to the search index, because it is new or has just been edited. The parameter $pageid contains the pageid from the database. The $request parameter contains the URL fragment used to view the page - this can be passed to qa_path() to generate a URL. The $title parameter contains the page's title in UTF-8 format. The $content, $format and $text parameters work the same as for index_post() above, but $format is currently always 'html'.

  • unindex_page($pageid). If defined, this function is called when a custom page should be removed from the search index, because it has been delted or is about to be edited (in which case index_page() will be called immediately after). Generally, the parameter $pageid matches a value previously passed to index_page() when the page was indexed. However in some circumstances the $pageid might never have been indexed, in which case the function should do nothing.

  • process_search($query, $start, $count, $userid, $absoluteurls, $fullcontent). If defined, this function allows the search module to replace the default Q2A search results with its own, if the module is selected by the site administrator. The $query parameter contains the entered search query in UTF-8 encoding. The parameter $userid identifies the user performing the query, or null if no user is logged in. The $absoluteurls and $fullcontent parameters are explained below. The function should return a nested array of up to $count search results for this query, starting at position $start>=0. Each element of the outer array is itself an inner array, which can contain one or more elements with the following keys:

    • 'question_postid' => the postid of the matching question. Use this to indicate a question page in general.
    • 'match_postid' => the postid of a specific matching question, answer or comment.
    • 'page_pageid' => the pageid of a matching custom page.
    • 'title' => the title to display for the search result.
    • 'url' => the URL for the search result, which must be absolute if $absoluteurls is true.

    A search result can refer to an external website by using only the 'title' and 'url' elements in the result's array. However, if one or both of these elements are present along with 'question_postid', 'match_postid' or 'page_pageid', then they are used to override the title or URL displayed for the question or page as appropriate.

    To save additional database queries, it is also possible to pass through more information about a matching question, post or page in 'question', 'match_type' or 'page' elements. This requires knowledge of Q2A's internals - see qa-app-search.php for more information on how these elements are used with the $fullcontent parameter.

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