How do I pass custom fields using Chat REST API?

Environment:

Chat
Oracle B2C Service

Resolution:

To pass the custom field in an EstablishSession REST call you will need to include the prefix "c." or "c$" to the name value when passing custom fields.

For example {\"name\" : \"c$location\", \"type\" : \"string\", \"value\" : \"200 Test Parkway Redwood Shores NJ 07036 USA\"} or you can also use ID values for example {\"name\" : \"c$location\", \"type\" : \"string\", \"value\" : \"102\"}

You can get further information on Chat REST API here then APIs & Schema -> REST API for Chat in B2C Service.

Note that the value of the custom field will not be bypassed if the request contains the incidentId attribute to associate the chat to an existing incident. See also Answer ID 13030: Incident values not being bypassed through Chat REST API requests.