Setting selected term_id with wp_dropdown_categories?

Question

I'm using this code to get the term_id of a custom taxonomy. The drop down does list the terms of the taxonomy Type. When I print the $terms variable I see the term ID of the post i'm editing on the front end. Why isn't the term ID being set as the selected option?

$terms = get_the_terms( $current_post, 'Type' );
print_r($terms);
wp_dropdown_categories( 'taxonomy=Type&hierarchical=1&hide_empty=0&id=cat&show_count=0&selected=' . $terms[0]->term_id );

This is the output of the array

Array ( [25] => stdClass Object ( [term_id] => 25 [name] => Sativa [slug] => sativa [term_group] => 0 [term_icon] => http://pothwy.com/wp-content/themes/GeoPlaces/images/default.png [term_price] => 0 [term_taxonomy_id] => 53 [taxonomy] => Type [description] => [parent] => 0 [count] => 4 [object_id] => 563 ) )

Output of HTML

<select name="cat" id="cat" class="postform">
    <option class="level-0" value="25">Sativa</option>
    <option class="level-0" value="52">Indica</option>
</select>

Answer 1

That's because you don't have the $terms[0] element. Use following code to get the first key of $terms array:

<?php
// Set the pointer to the first element
// you don't need this if there is the only array element
reset($terms);
// get the key of the current position
$selected_id = key($terms);

You MUST enable WP_DEBUG when on develop stage to see important information you don't see now:

Notice: Undefined offset: 0 in /home/...
Notice: Trying to get property of non-object in /home/...