Grouping or Aggregating items in workflow based on a field value

Hi @pemontto,
This is a sample/example output from (API call + SET module) to filter out unnecessary fields (for this mock data, I have limited the output to 10 items, with each item representing 1 product):

[
  {
    "id": 1612,
    "producer_id": 131,
    "on_hand": 1,
    "price": "1.12",
    "product_name": "Yarrow - Terracotta"
  },
  {
    "id": 1611,
    "producer_id": 131,
    "on_hand": 2,
    "price": "2.75",
    "product_name": "Rose - Distant Drums"
  },
  {
    "id": 1610,
    "producer_id": 145,
    "on_hand": 0,
    "price": "2.75",
    "product_name": "Rose - Distant Drums"
  },
  {
    "id": 1609,
    "producer_id": 145,
    "on_hand": 4,
    "price": "10.0",
    "product_name": "Falda Light Apricot"
  },
  {
    "id": 1608,
    "producer_id": 145,
    "on_hand": 5,
    "price": "5.23",
    "product_name": "Northern Sea Oats"
  },
  {
    "id": 1606,
    "producer_id": 223,
    "on_hand": 10,
    "price": "6.38",
    "product_name": "Pomegranate"
  },
  {
    "id": 593,
    "producer_id": 145,
    "on_hand": 3,
    "price": "6.38",
    "product_name": "Strawflower - Golden Short"
  },
  {
    "id": 592,
    "producer_id": 223,
    "on_hand": 7,
    "price": "8.27",
    "product_name": "Celway Pink Mix"
  },
  {
    "id": 591,
    "producer_id": 145,
    "on_hand": 7,
    "price": "9.93",
    "product_name": "Ornamental - White"
  },
  {
    "id": 590,
    "producer_id": 145,
    "on_hand": 2,
    "price": "9.43",
    "product_name": "Ornamental - Pink"
  }
]

This sample data contains 10 products from 3 producers (identified by the producer_id field - 131,145, and 223). Now, I want to generate 3 CSV files containing all the fields (id, price, on_hand, product_name, producer_id), one for each producer.

Therefore,
Producer no. 131’s CSV should have 2 products, Producer 145’s CSV should have 6 products, and Producer 223’s CSV should have 2 products.

When I use Spreadsheet module directly, I get everything in 1 CSV (Which I don’t want)

Using Item List: Aggregate Module, I get different arrays/list for each field I choose to aggregate, rather than all the field grouped by producer_id.