When creating class functions, it may be easy to forget to prefix the function definition with the "exposed" keyword. For example, here is an entity selection class function for Table_1:

Class extends EntitySelection Function test123    $0:="hello world"

Next, a POST request made to a class function "test123" via "http://localhost/rest/Table_1/test123".



Note that without the exposed keyword, the class function test123 is not found. When including it:

Class extends EntitySelection exposed Function test123    $0:="hello world"