SoapUI how to get property transfer TestStep in Script Assertion of the next step - groovy

Question

I'm using SoapUi 5.3.0 to test a case like this:
I have 3 apis: Book list, Add a book to favorite list, and Favorite list.
I add 3 apis to a TestCase as TestSteps to test the case: User views book list, choose the first book in the list then adds to favorite list, after that user goes to favorite list to verify that the book is displayed in the first place in Favorite list.
I add a propertyTransfer between step 1 and step 2, to get book_id from respond of step 1, then use to a param of the next step's request.
At step 3, I add an assertion by Script Assertion like below:
import groovy.json.JsonSlurper
//get propertyTransfer value
def tcProperty = messageExchange.modelItem.testStep.testCase.getTestStepByName("propertyTransfer").getPropertyValue("book_id")
// get response message of Favorite book api
def responseMessage = messageExchange.response.responseContent
// get book_id of the first book in favorite list
def jsonSlurper = new JsonSlurper().parseText(responseMessage)
bookId = jsonSlurper.data[0].book_id
// verify
assert bookId == tcProperty
But the script returns failed, and an error displays like attach photo
It seems tcProperty is null, means I could not get propertyTransfer value.
So where am I wrong?

Answer 1

You can either use Property Transfer test step or without it i.e., using Script Assertion for the request step itself.
If Script Assertion is used, then Property Transfer step is not needed at all.
The idea is extract the required value, and set it at test case level custom property in the Script Assertion.
Now, you want to use the above extracted value in the next step, which can be done using property expansion.
Here is the script assertion:
//Check if the response is not empty
assert context.response, 'Response is empty or null'
def jsonSlurper = new groovy.json.JsonSlurper().parseText(context.response)
bookId = jsonSlurper.data[0].book_id
assert bookId, 'Book id is empty or null'
//Set the bookId as test case level property
context.testCase.setPropertyValue('BOOK_ID', bookId)
In the next step, use property expansion i.e., ${#TestCase#BOOK_ID} where ever you needed book id