Get the value of a custom field

Summary

How to fetch a custom field value from the contact table in PHP

Content

Hello,

I have a PHP page that needs to know whether a boolean custom field is set to Yes or No. The custom field is for the Contacts table.

I have tried to use the approaches from several of the other questions that were answered in this space about fetching values from custom fields or custom objects. However I keep getting errors.

The custom field is called "consultant", and  I've tried several iterations of the code below and it is always throwing errors when I load the page.