add_where() causes the view not to be displayed

Question

have a page that features a few views based on content types. Each content type includes a keyword field. This page is reached from a short quiz. I'm trying to limit the content in the views based on responses in the quiz by pulling the $_POST data and comparing it to the keyword field. The code is executing, and I'm fairly sure I have the join right, but instead of limiting the content to matching keywords, the entire display block just disappears.

Here is my module code:

<?php

if (!empty($_POST["q1"])) {

    $q1 = $_POST['q1'];
    $q3 = $_POST['q3'];

    /**
     * Implements hook_views_query_alter to add a where clause to the views queries
     */
    function iamru_keyword_filter_views_query_alter(&$view, &$query) {

        global $q1, $q3;

        if ($view->name == 'iamru_prepared_statement') {
            $query->add_table('field_data_field_keyword');
            $query->add_where(1,'field_data_field_keyword.field_keyword_value', $q1, '=' );
        }

        if ($view->name == 'iamru_word_for_you_view') {
            $query->add_table('field_data_field_keyword');
            $query->add_where(1,'field_data_field_keyword.field_keyword_value', $q3, '=' );
        }

    }

}

Can anyone see where I've gone wrong here?

Interesting update: If I replace $q1 with 'somekeyword' in the add_where call, it actually works.

Answer 1

It was a problem with accessing the global variables. In the end, I got it working with the following function:

function iamru_keyword_filter_views_query_alter(&$view, &$query) {

        $q1 = $GLOBALS["_POST"]["q1"];
        $q3 = $GLOBALS["_POST"]["q3"];

        if ($view->name == 'iamru_prepared_statement') {
            $query->add_table('field_data_field_keyword');
            $query->add_where(1,'field_data_field_keyword.field_keyword_value',  $q1, '=' );
        }

        if ($view->name == 'iamru_word_for_you_view') {
            $query->add_table('field_data_field_keyword');
            $query->add_where(1,'field_data_field_keyword.field_keyword_value',  $q3, '=' );
        }

    }

Answer 2

You can access the content of a where condition modifying its value:

$query->where[0]['field_condition'][0]['value'] = 'something...';

Pretty similar what you did with orderby. Also you can add custom where conditions add_where_expression