Use a form to filter table data in a module

Question

I have made a module in Drupal 6 that builds a page that shows some data taken from an external database. I want to add a form that let the user filter the data (for example, limit the data output to a specific city instead all the cities). How can I get the value of the submitted form and use it as a filter condition on the page rendering function? The $form_state variable doe not exist when running the page function and I have no way to load the value.

Answer 1

It sounds like your problem is about passing the selected value to your page rendering function, upon form submission. There are a few different ways to pass that value from within the form_submit function, including via a URL argument, or setting a cookie, or using some javascript to post the value - or even using variable_set() in the right circumstances. There might be easier better ways than those, and I'd like to know what they are if they exist.

Here's a way to do it via a URL argument:

1. In the form_submit() function, pass the select data to the page rendering function via drupal_goto(). Eg: drupal_goto( 'this/page/' . $form_state['values']['city']

2. Be sure that your page rendering function can accept the right argument. in your hook_menu:
   'page arguments' => array( 2 ),
   (or you can just grab the argument using arg( 2 ) from within the page rendering function)

I'm not saying this is necessarily the best way to get the job done, but this should work.

Answer 2

You could make the external database table visible to Views by using hook_views_data(). Rather than add in a form, you could then leverage the power of Views and have exposed filters.