How to integrate tables to one document

Elastic Search
1

I have three tables as RDS, each refers to products, categories and genres
The relation is that a product has many genres and a category has many genres and foreign keys tie them up.

I want to make it possible to search them by product name, genres and categories.
Could you show me the best practice to integrate them into documents.

2

Our usual recommendation is to flatten your data. So flatten everything down to a single record that has the genre and category inlined...

{
  "product": "1",
  "genre": ["comedy", "romance"],
  "category" ["entertainment"]
},
{
  "product": "2",
  "genre": ["comedy"],
  "category" ["entertainment", "sports"]
}