Gravity Forms API traps that cost us hours (and how to post code here)

<p>Four lessons from production code on our own sites. Each one cost us an afternoon.</p><ol><li><strong>REST <code>PUT</code> replaces the whole object.</strong> <code>PUT /gf/v2/entries/{id}</code> with one field in the body wipes every other field on the entry. <code>PUT /gf/v2/forms/{id}</code> does the same to a form, notifications and confirmations included. Fetch the full object, change it, and send all of it back.</li><li><strong>For one field, use <code>GFAPI::update_entry_field()</code>.</strong> It changes a single value without touching the rest of the entry, and it doesn't fire feeds or notifications.</li><li><strong>Custom merge tags shaped like <code>{label:123}</code> get eaten.</strong> Gravity Forms treats any <code>{anything:digits}</code> as a field merge tag and substitutes it before <code>gform_replace_merge_tags</code> runs. Handle your tag in <code>gform_pre_replace_merge_tags</code>, or use a shape that doesn't collide, like <code>{label|123}</code>.</li><li><strong><code>gform_merge_tag_filter</code> doesn't get the tag's label.</strong> Its second argument is the field or input ID, so checking it for a label string never matches.</li></ol><p><strong>Posting code here</strong></p><ul><li>Say where it runs: <code>functions.php</code>, a snippet plugin, or an mu-plugin, plus the hook and priority.</li><li>Include the Gravity Forms version you tested on.</li><li>Strip API keys, license keys, and URLs you don't want public.</li><li>Keep short snippets inline. Put anything longer in a GitHub Gist so the indentation survives.</li></ul><p>Looking for something ready-made? Our <a href="https://brightleafdigital.io/code/">snippet library</a> is free, and every snippet links to its GitHub source.</p>