Faceted search with categories using Low Search

Question

So I am trying to set up a faceted search which is based on categories - but EE's default category parameters aren't clever enough for me with just the & or | separators, so I was wondering if I could do what I need to with Low Search.

I have 5 category groups: Age, Artists, Type, Medium and Topic. In each of these is an unknown number of categories. I am displaying checkboxes on the front end for each category group, and have entries assigned to at least 1 category in each group. Here is my list of filters so you can see the options:

The default view when nothing is ticked is all entries. If I tick 'Multiple' I want all entries categorised with 'Multiple' to show. When I have 'Multiple' and '8-10' ticked I would like everything categorised as both 'Multiple' and '8-10' to show. So far so easy - but here is where EE's default breaks:

I tick 'Multiple', '8-10' and '11-14' I want to show everything that is categorised as 'Multiple' and '8-10' or 'Multiple' and '11-14'.

I hope this makes sense and isn't too long winded - ask if something isn't clear and I'll try to clarify. Does anyone know if this is possible with Low Search, and if not - how might I go about it?

Thanks!

Answer 1

Yep, that would be a job for the Categories filter.

For each group of categories, use a category:group_name parameter name to combine AND and OR matching. For example:

{exp:channel:categories category_group="1" style="linear"}
  <label>
    <input type="checkbox" name="category:group1[]" value="{category_id}"
    {if category_id IN ({low_search_category:group1})} checked="checked"{/if} />
    {category_name}
  </label>
{/exp:channel:categories}

{exp:channel:categories category_group="2" style="linear"}
  <label>
    <input type="checkbox" name="category:group2[]" value="{category_id}"
    {if category_id IN ({low_search_category:group2})} checked="checked"{/if} />
    {category_name}
  </label>
{/exp:channel:categories}

...

And repeat for each other category group. Note: this code should be put inside the Form tag.

Answer 2

If hitting "Unexpected ‘IN’ (VARIABLE); expected RD in Template" error in EE 2.9.2 try swapping conditional from

{if category_id IN ({low_search_category:group2})} checked="checked"{/if} />

to

{if category_id ~ '/(^|\|)'.low_search_category:group2.'($|\|)/'} checked="checked" {/if}