WordPress query builder class

Builder.php

<?php

/**
 * Builds a WP_Query object using a fluent interface.
 *
 * @author Carl Alexander <contact@carlalexander.ca>
 */
class WP_Query_Builder
{
    /**
     * The query arguments collected by the query builder.
     *
     * @var array
     */
    private $query_arguments;

    /**
     * Constructor.
     *
     * @param array $query_arguments
     */
    public function __construct(array $query_arguments = array())
    {
        $this->query_arguments = array_merge(array(
            'no_found_rows' => true,
            'update_post_meta_cache' => false,
            'update_post_term_cache' => false,
        ), $query_arguments);
    }

    /**
     * Generates a group of query arrays using the given query arrays. The query
     * result must match all the given query arrays.
     *
     * @param array ...$query_arrays
     *
     * @return array
     */
    public function and_where()
    {
        $query_arrays = func_get_args();

        $query_arrays['relation'] = 'AND';

        return $query_arrays;
    }

    /**
     * Generates a taxonomy array for a category.
     *
     * @param array|string $categories
     * @param string $field
     * @param string $operator
     * @param bool $include_children
     *
     * @return array
     */
    public function category($categories, $field = 'term_id', $operator = 'IN', $include_children = true)
    {
        return $this->taxonomy('category', $categories, $field, $operator, $include_children);
    }

    /**
     * Specify the post types that the query will retrieve.
     *
     * Can be a comma separated string or an array. Overwrites previous
     * specification criteria if called multiple times.
     *
     * @param string|array $from
     *
     * @return self
     */
    public function from($from)
    {
        if (is_string($from)) {
            $from = array_map('trim', explode(',', $from));
        } elseif (!is_array($from)) {
            return $this;
        }

        $this->query_arguments['post_type'] = $from;

        return $this;
    }

    /**
     * Query WordPress using the current specifications of the builder.
     *
     * @return WP_Post[]
     */
    public function get_results()
    {
        var_dump($this->query_arguments);
        $query = new WP_Query($this->query_arguments);

        return $query->posts;
    }

    /**
     * Generates a taxonomy array where posts have one of the given categories.
     *
     * @param array|string $categories
     * @param string $field
     * @param bool $include_children
     *
     * @return array
     */
    public function in_category($categories, $field = 'term_id', $include_children = true)
    {
        return $this->in_taxonomy('category', $categories, $field, $include_children);
    }

    /**
     * Generates a taxonomy array where posts have one of the given
     * taxonomy terms.
     *
     * @param string $taxonomy
     * @param array|string $terms
     * @param string $field
     * @param bool $include_children
     *
     * @return array
     */
    public function in_taxonomy($taxonomy, $terms, $field = 'term_id', $include_children = true)
    {
        return $this->taxonomy($taxonomy, $terms, $field, 'IN', $include_children);
    }

    /**
     * Specify the maximum number of results that the query will retrieve.
     *
     * Overwrites previous specification criteria if called multiple times.
     *
     * @param int $limit
     *
     * @return self
     */
    public function limit($limit)
    {
        if (!is_numeric($limit)) {
            return $this;
        }

        $this->query_arguments['posts_per_page'] = (int) $limit;

        return $this;
    }

    /**
     * Generates a taxonomy array where posts don't have one of the given categories.
     *
     * @param array|string $categories
     * @param string $field
     * @param bool $include_children
     *
     * @return array
     */
    public function not_in_category($categories, $field = 'term_id', $include_children = true)
    {
        return $this->not_in_taxonomy('category', $categories, $field, $include_children);
    }

    /**
     * Generates a taxonomy array where posts don't have one of the given
     * taxonomy terms.
     *
     * @param string $taxonomy
     * @param array|string $terms
     * @param string $field
     * @param bool $include_children
     *
     * @return array
     */
    public function not_in_taxonomy($taxonomy, $terms, $field = 'term_id', $include_children = true)
    {
        return $this->taxonomy($taxonomy, $terms, $field, 'NOT IN', $include_children);
    }

    /**
     * Generates a group of query arrays using the given query arrays. The query
     * result must match one of the given query arrays.
     *
     * @param array ...$query_arrays
     *
     * @return array
     */
    public function or_where()
    {
        $taxonomy = func_get_args();

        $taxonomy['relation'] = 'OR';

        return $taxonomy;
    }

    /**
     * Specify the order of the query results.
     *
     * Overwrites previous specification criteria if called multiple times.
     *
     * @param string|array $sort
     * @param string $order
     *
     * @return self
     */
    public function order_by($sort, $order = 'DESC')
    {
        if (empty($sort) || (!is_array($sort) && !is_string($sort))) {
            return $this;
        } elseif (!is_string($order) || !in_array(strtoupper($order), array('ASC', 'DESC'))) {
            $order = 'DESC';
        }

        $this->query_arguments['orderby'] = $sort;
        $this->query_arguments['order'] = $order;

        return $this;
    }

    /**
     * Specify the columns that the query will retrieve.
     *
     * Overwrites previous specification criteria if called multiple times.
     *
     * @param string $select
     *
     * @return self
     */
    public function select($select)
    {
        if (empty($select) || !is_string($select)) {
            return $this;
        }

        $this->query_arguments['fields'] = $select;

        return $this;
    }


    /**
     * Generates a taxonomy array for a tag.
     *
     * @param array|string $tags
     * @param string $field
     * @param string $operator
     * @param bool $include_children
     *
     * @return array
     */
    public function tag($tags, $field = 'term_id', $operator = 'IN', $include_children = true)
    {
        return $this->taxonomy('tag', $tags, $field, $operator, $include_children);
    }

    /**
     * Generates a taxonomy array.
     *
     * @param string $taxonomy
     * @param array|string $terms
     * @param string $field
     * @param string $operator
     * @param bool $include_children
     *
     * @return array
     */
    public function taxonomy($taxonomy, $terms, $field = 'term_id', $operator = 'IN', $include_children = true)
    {
        if (!is_array($terms)) {
            $terms = array($terms);
        }

        return array(
            'taxonomy' => $taxonomy,
            'field' => $field,
            'terms' => $terms,
            'operator' => $operator,
            'include_children' => $include_children,
        );
    }

    /**
     * Specify the taxonomy of the posts that the query will retrieve.
     *
     * @param array ...$taxonomies
     *
     * @return self
     */
    public function where_taxonomy()
    {
         $this->query_arguments['tax_query'] = array_reduce(func_get_args(), array($this, 'merge_query_argument'));

        return $this;
    }

    /**
     * Merges the given query array argument into the given query.
     *
     * @param mixed $query
     * @param array $query_argument
     *
     * @return array
     */
    private function merge_query_argument($query, array $query_argument)
    {
        if (!is_array($query)) {
            $query = array();
        }

        if (!isset($query_argument['relation'])) {
            $query_argument = array($query_argument);
            $query_argument['relation'] = 'AND';
        }

        $query['relation'] = $query_argument['relation'];
        unset($query_argument['relation']);

        foreach ($query_argument as $query_array) {
            $query[] = $query_array;
        }

        return $query;
    }
}