Features used to implement the example

• Set a field as a function of other fields

Example: Assign issue to current user if the user is not member of a certain project role

I need to create a post-function to assign the issue to the current user only when the user is not member of a particular project role.
Is it possible?

You have to use Set a field as a function of other fields post-function with the following configuration:

Setting rule used is:

[!isInRole(%{00020}, "name_of_project_role")]%{00020}

Note that:

• %{00020} is field code for "Current user"
• Value selected for parameter "Field to be checked..." is irrelevant, since we only used a type 2 setting rule

Once configured, transition will look like this: