Summary of Changes

A customer of mine gave me feedback that they would like to be able to influence the ordering of search results in Smart Search. Specifically, they have content that doesn't contain the key words very often, but is nearly always more relevant to the searching user than other, more keyword-dense content. They would like a feature to push that content further up in the search results.

I've been thinking about ways to do this and there would be several options. We could introduce a "featured" flag and then sort by "featured" and then by relevance or we could add a modifier/multiplier to the contexts for the content of such featured content. Both proposals have their downsides, quite a few being the complexity to implement in the current structure.

This implementation allows to set an integer modifier per content item in the index, which the weight for the relevance is multiplied with for the right ordering. There is no direct GUI to modify this, but this is supposed to be handled by the developer of the finder plugin. As an example, featured articles and contacts get a modifier of 5 and thus a higher relevance than non-featured items. You could expose this in the GUI of your extension directly or you could use a ridiculously high modifier to sort by type before relevance. (For example in a site with a shop, you might want to give all products a modifier of a million, so that in the search results products always come first.)

NOTICE: Since we are adding a new column to the #__finder_links table and a new attribute to the Result object, we unfortunately invalidate all serialised objects in that table from earlier indexing and will get errors in the frontend when we want to use this old data. Thus we need to reindex the content. We DON'T need to clear the index first. By setting the md5sum column to an empty string, we are forcing a reindexing without clearing the index first and with that clearing all of the filters and their IDs.

Testing Instructions

1. Setup a site with Smart Search
2. Mark an article as featured.
3. Search for something and remember the ordering. The featured article shouldn't be at the top of the results.
4. Apply the patch including the database changes.
5. Click the Index button in the backend.
6. Search for the term from 3. again

Actual result BEFORE applying this Pull Request

You get the same result as in 3.

Expected result AFTER applying this Pull Request

The featured article shows up a lot further up than in 3.