We're trying to automate the transfer of data from Hubspot to WordPress via Zapier. We've created "partners" in our WordPress app, which we create by posting to:
Do we need to do something special to make these fields writable via the API?
We tried using register_meta, but, that obviously just makes identically named fields become writable in the meta hash, but doesn't allow us to modify the values in toolset-meta.
The REST API add-on for Types is used to expose the formatted values of Types custom fields to REST read requests.
Types custom fields are regular custom fields, i.e. stored in wp_postmeta, accessible via the normal WordPress functions such as update_post_meta and get_post_meta, with one proviso: the meta_key is the Types field slug with a 'wpcf-' prefix (e.g. a 'priority' custom field is stored with a meta_key of 'wpcf-priority).
Many fields which are stored as simple text. Some have formatting options when they are output by types shortcodes (or, now, using blocks), e.g. to output a date field in a specified date format.
The fields are always accessible (and writable) in the same way as standard post meta, including when using the REST API, so if you need to update custom fields via REST, that's the way to go.
The Toolset custom fields are exactly like WordPress default ones, so if for the default custom fields you will need the register_meta then for Toolset fields you also need that.