Need a complex dispatcher on query parameter

[RKALPFR]

Hi all,
Firstly, i'm sorry if this question has been still asked but i didn't find it. And i didn't find similar point into documentation.

I'm looking for mock the following endpoint : /myApi/action?number=MYNUM

To be representative and usefull, we need to dispatch response to dynamics templates respecting the following rule :

1. All requests whose MYNUM starts with '1A' should respond with the file ex1.json
2. All requests whose MYNUM starts with '1B' should respond with the file ex2.json
3. All requests whose MYNUM starts with '3P' should respond with the file ex3.json
4. All others should respond with the file default.json

For automation use, the "start with" is very important.

I've tried with script but i've never access to the query_parameter.

Has someone a response?