Unable to add columns to the Terms List table

[dglingren]

The base class WP_List_Table and its extended family is a great addition to the WordPress administration API. The WP_Posts_List_Table class has well-documented filters that support adding custom columns to the default table.

However, custom column support in the WP_Terms_List_Table class is incomplete. There is a filter in the column_default method, but it is useless because there is no filter in the get_columns method to allow expanding the column array.

Please consider changing the last line of the get_columns method to something like:

return apply_filters( "manage_{$taxonomy}_custom_get_columns", $columns );

or

return apply_filters( "manage_{$taxonomy}_columns", $columns );

The affected file is wp-admin/includes/class-terms-list-table.php. The choice for the filter name depends on whether you want to follow the convention used in the WP_Terms_List_Table class (first alternative) or the convention used in the WP_Posts_List_Table class (second alternative).

This one-line change would finish the job of making the default table expandable. Thank you for your consideration.

[SergeyBiryukov]

You can use manage_{$screen->id}_columns filter from WP_List_Table:
​http://core.trac.wordpress.org/browser/tags/3.4.1/wp-admin/includes/class-wp-list-table.php#L89

For categories and tags, it's manage_edit-category_columns and manage_edit-post_tag_columns.

Closing as a duplicate of #20913.

[michelwppi]

To add the columns this filter manage_edit-category_columns is ok (add columns and title)

BUT

to fill each line of terms the filter "manage_{$screen->taxonomy}_custom_column" must not be a filter(if used: only first filter is possible as returned content and the other filter must echo the row ;-).

It must be an action like in line 671 of wp-posts-list-table

do_action( "manage_{$post->post_type}_posts_custom_column", $column_name, $post->ID );

so in line 318 solution fixe is

do_action( "manage_{$screen->taxonomy}_custom_column",  $column_name, $tag->term_id );

Hope that help to understand our tests

M.

[nacin]

Line 319, give or take:

return apply_filters( "manage_{$screen->taxonomy}_custom_column", '', $column_name, $tag->term_id );

Return your content (rather than echoing, as occurs with the posts table).

[michelwppi]

BUT if you have two (or more filters), only the first returned value is displayed and for the second filter (another added column) you must echo..

[nacin]

Works fine for me:

add_filter( 'manage_edit-post_tag_columns', function( $cols ) {
	$cols['col1'] = 'Column 1';
	$cols['col2'] = 'Column 2';
	return $cols;
} );

add_filter( 'manage_post_tag_custom_column', function( $content, $column, $term_id ) {
	return "We are in $column for $term_id";
}, 10, 3 );

[michelwppi]

OK, you are right - the mistake came from first param 'empty' kept as a dummy var and not the content ... I change my way to manage content like here:

function co_manage_tax_column ( $content, $name, $id ) {
	if( $name != 'linked-post' )
			return $content;
	global $taxonomy ;
	$term = get_term((int)$id , $taxonomy ) ;	
	$a = $term->slug;
		
	//echo '<div>*'. $a .'</div>';	
	return $content.$a;	
}
add_filter( 'manage_category_custom_column', 'co_manage_tax_column', 12, 3);

and now, no interferences between the 2 filters for the two added columns.

Many thanks for your help to go deeper

M.