Using years as facets in Low Search faceted search

Question

I am creating a faceted search using Low Search with the help of this post. I would like to include a list of years as a facet, too, but I only want years listed where there is an entry. For example, if I had an entries in 2004, 2005, 2007, 2010 and 2014, I'd want those to be what displays, but not 2006, 2008, 2009, etc. I'm stumped.

UPDATE APRIL 10: I've made some headway! Using Low's "Ranges" examples (scroll down to "Show entries for a given month"), I created my list of years. I'd really like to be able to generate the range dynamically so that I don't have to manually change the range every year. I created a low variable that outputs the year, but when I use it as the parameter value it creates a list of numbers starting from zero.

Here's my search code with the manual range that works:

{exp:low_search:form form_id="search" result_page="docs/index" query="{segment_2}"}

…other facets…

<fieldset>
    <legend>Year</legend>
    {exp:low_list:each items="2014|2003" as="year" range="yes"}
        <label>
        <input type="checkbox" name="year" value="{year}"{if low_search_year == year} checked{/if} />
            {year}
        </label>
    {/exp:low_list:each}
</fieldset>
<input type="submit" class="btn btn-small" value="Filter" />
{/exp:low_search:form}

And here's my search code with the low variable used in the range, which outputs a list of numbers starting at 0 (the variable when not used as a parameter value outputs just fine):

{exp:low_search:form form_id="search" result_page="docs/index" query="{segment_2}"}

…other facets…

<fieldset>
    <legend>Year</legend>
    {exp:low_list:each items="{exp:low_variables:single var='lv_var_doc_library_published_year' preparse:var_doc_library_sort='desc'}|2003" as="year" range="yes"}
        <label>
        <input type="checkbox" name="year" value="{year}"{if low_search_year == year} checked{/if} />
            {year}
        </label>
    {/exp:low_list:each}
</fieldset>
<input type="submit" class="btn btn-small" value="Filter" />
{/exp:low_search:form}

Does anybody have any ideas about how I can dynamically populate the parameter value?

Answer 1

How about using the Query module? Something like...

<select name="year">
  {exp:query sql="SELECT DISTINCT year FROM exp_channel_titles WHERE channel_id = X ORDER BY year DESC"}
    <option value="{year}">{year}</option>
  {/exp:query}
</select>

...where X is the channel ID you want to target.

Answer 2

I would honestly consider using some PHP snippet's and PHP Parsing set to input. It'd come out much cleaner! This way your php can populate the attributes for you. I assume you want 2003 to current year right?

<?php
    $startYear = 2003;
    $endYear = intval(date("Y",time()));
?>

{exp:low_search:form form_id="search" result_page="docs/index" query="{segment_2}"}

    …other facets…

    <fieldset>
        <legend>Year</legend>
        {exp:low_list:each items="<?php echo $startYear . '|' . $endYear; ?>" as="year" range="yes"}
            <label>
                <input type="checkbox" name="year" value="{year}"{if low_search_year == year} checked{/if} />
                {year}
            </label>
        {/exp:low_list:each}
    </fieldset>

    <input type="submit" class="btn btn-small" value="Filter" />

{/exp:low_search:form}