I am able to upsert contact info using Email but when I try to do the same with MobilePhone (or Phone) I get the following error: "Provided external ID field does not exist or is not accessible: MobilePhone". The input includes a MobilePhone value and I am able to create a contact using the exact same input values.

I am using the restforce Ruby gem.

I'm creating an integration with Salesforce that just upserts a contact using an ID from my system. When my app user authorizes the oAuth integration in Salesforce I want to automatically create a new custom Contact field. Is that possible using the REST API? If so, how? Or is there an alternative automatic method I can use?

I'm using the restforce Ruby gem.

I'm creating an integration with Salesforce that just upserts a contact using an ID from my system. When my app user authorizes the oAuth integration in Salesforce I want to automatically create a new custom Contact field. Is that possible using the REST API? If so, how? Or is there an alternative automatic method I can use?

I'm using the restforce Ruby gem.