How to write a if condition to set a variable value based on another variable value in Watson assistant

I am working on Watson assistant. I need to set the value of a variable "service_option" based on the value of the variable "service_line". I need to write the code within Watson assistant expression. I heard that Watson assistant Uses Spring Boot Expression Language with some modification but I still couldn't figure out how to write the if condition and then set the variable value. The closest I came was like this: $service_line == "Cloud" ? service_option = {"AWS","Azure","Google"} but the above code is not working.there was no error but the variable "service_option" is not getting assigned and when I assigned it for dynamic option, no options are being displayed.

service_line can has any value of "Cloud", "Machine Learning" and "Full stack" and based on the value of the service_line I need to set the value of service_option which should be an array so that I can pass the service_line option as a dynamic variable for the "option" user response type.

It's Spring Expression Language (SpEL).

As to how to do this.

Dialog

The following should work in dialog.

$response = "<? $service_line == \"Cloud\" ? \"Yes\" : \"No\" ?>"

The <? ?> means to execute the code block replace that block with the response.

Dialog uses what is called Autoboxing. So although a string returns, later logic can read it as a different object type.

Actions

There are two approaches.

You can add the following as an expression response to assigning to a variable.

${service_line} == "Cloud" ? "Yes" : "No"

In actions the <? ?> doesn't work anymore and should not be used. Instead you just wrap the piece with ( ) so that it executes first. Like so.

${response} = (${service_line} == "Cloud" ? "Yes" : "No")

Here is an example image of the UI (You only need one of the lines).

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To cover the second part of your question. (Which I will explain in Actions but you should be able to convert over)

To check an array you would do something like this:

${response} = (["AWS","Azure","Google"].contains(${service_line}) ? "Yes" : "No")