This is an ExpressionEngine extension that creates global variables from channels and fields which outputs the channel/field id.
This is useful especially when writing queries using the Query module. Imagine there is a channel named blog
and a field named blog_location
. Normally, you would hardcode the field id and the channel id in the query.
{exp:query sql="SELECT field_id_1 AS blog_location FROM exp_channel_data WHERE channel_id = 1"}
{blog_location}
{/exp:query}
In the next example, we will use the global variables for field id and channel channel_id
{exp:query sql="SELECT {field_blog_location} AS blog_location FROM exp_channel_data WHERE channel_id = {channel_blog}"}
{blog_location}
{/exp:query}
Another example would be for use in a module or fieldtype. This is not a good solution for distributable add-ons, but if a custom add-on is being written for a client, it is a good way to keep from having to always use the channel or field id.
$blog_location = $this->EE->config->_global_vars['field_blog_location'];
$blog_channel_id = $this->EE->config->_global_vars['channel_blog'];