How to add entry to associated tables

I am using postgres database

I am having two collection category and services

Category hasMany association with services

So if need to put entry category table and service table with newly created categoryid means. how can i do that ?

Ex: POST http://localhost:1337/category

    "category_name": "Mobile",
    "services": [{
        "service_name": "repair"

It throwing error invalid input syntax for type integer: "{