Ninja Form=8 provides the fields for collecting information needed to create the Campaign or used by the theme. Generally to set the field “x”, use a field key of “x”; that is, the field with key “post_title” sets the “post_title” of the Campaign post. The exception is the thumbnail image; since a field key that starts with underscore (_) is illegal, a key with “thumbnail_id” sets the post_meta field of “_thumbnail_id”.
The plugin provides an extension to Ninja Forms for selecting items whose key ends in “_causeid”. By having a field with key kids_causeid, that
select field is populated with a drop-down of the titles of all items of custom_post_type “kids” with values of their post ID. Likewise, the field with key “projects_causeid” populates a drop-down with the titles and IDs of all “projects”.
The plugin also provides an extension to Ninja Forms for setting the post_meta. Any form field that is not already handled (such as post_title) and doesn’t end in “_” (which is the autogenerated field keys) is used in update_post_meta.