How to alter the state of a radio button in an exposed filter to "checked" based on the view URL?

Question

I have a D7 site where I have several main topics, each containing subtopics. I've made a views block which is shown on each of the pages of the main topics where you have two filter options:

• Filter on main topic
• Filter on subtopic

The idea is that when the user enters a URL like www.mysite.com/topics/maintopic, the main topic filter radio button is set automatically to the main topic the user entered and the first sub-topic for that main topic.

So how can I do that? I tried with a contextual filter, but unless I missed something I don't see an option to preselect a radio button in an exposed filter (nor in fact to filter basing on the last part of a URL, unless it's an argument). I also tried the following code.

function MYMODULE_form_views_exposed_form_alter(&$form, &$form_state) {
  // ...
} 

I didn't see any option to alter which radio button is selected.

Answer 1

You will need to use 2 contextual filters as each one takes a different argument, for example www.mysite.com/filter1/filter2.

You're confusing the difference between exposed filters and contextual filters, and their behaviour. An exposed filter is form based. As you want a radio button, that's perfect. However, an exposed filter passes its values either via POST or GET; the only way to get these values through the URL is via the query string.

Answer 2

You can use hook_form_alter or hook_views_pre_render and check the url with $_GET or current_path() ,it's the fast and easy way.

Or you can play with Views create entity reference Filter (entityreference_filter) add your CONTEXTUAL FILTERS after that in your view add Reference Filter in Filter Criteria.