Hello team,
Some properties only allow us to set a value on creation of a new object, but not when we update it. However, there doesn’t appear to be any way for us to validate if a property can be used this way - this obviously isn’t ideal at all when allowing end users to map an integration themeselves, and they can choose any writeable property, but then their edits fail because some of the properties aren’t editable after creation. How can we manage this?
Hey @JP98,
Currently, HubSpot does not expose a flag in the properties API to indicate if a property is only writable at creation. This creates uncertainty in integration setups where users can map to any “writable” property.
You can use GET /crm/v3/properties/{objectType} to fetch the list and filter out readOnlyValue: true and readOnlyDefinition: true, but keep in mind that this still won’t catch “write-once” cases.
Refer:
Regards,
Great answer, @kosalaindrasiri 
Thank you! — Jaycee
Thanks @kosalaindrasiri - that’s what I had already been using, but it’s still super unhelpful that a property doesn’t show as readonly, yet when we push data to it, it rejects it as being read only after creation. We have no reliable way of capturing this to alert the user when they choose to push data to this property that it will only work once, and after that will break the integration.
Hey, @JP98 If you have the time, submitting your feedback for developer-related product functionality would be appreciated — Developer Feedback form. Please note, it is not a support form, but it is designed for these types of comments from developers.
Best,
Jaycee