How to get flat aggregation of two calls to json_agg - postgresql

Question

I have the following tables:
products
id | name
----+-------------
1 | Shampoo
2 | Conditioner
productOptions
id | name | productId
----+-------------+-----------
1 | Hair Growth | 1
2 | Frizzy Hair | 1
images
id | fileName | productOptionId
----+-----------+-----------------
1 | bee.png | 1
2 | fancy.png | 2
3 | soap.png | 2
products have many productOptions, and productOptions have many images.
Following from this question, I have aggregated images.fileName twice to get an aggregated list of the fileNames for each product:
SELECT p.name, o.options, o.images
FROM products p
LEFT JOIN (
SELECT "productId", array_agg(name) AS options, json_agg(i.images) AS images
FROM "productOptions" o
LEFT JOIN (
SELECT "productOptionId", json_agg(i."fileName") AS images
FROM images i
GROUP BY 1
) i ON i."productOptionId" = o.id
GROUP BY 1
) o ON o."productId" = p.id;
name | options | images
-------------+-------------------------------+------------------------------------------
Shampoo | {"Hair Growth","Frizzy Hair"} | [["bee.png"], ["fancy.png", "soap.png"]]
Conditioner | |
I am wondering how to flatten the second json_agg so that the list of images is flat, and if my overall approach makes sense.

Answer 1

I didn't have to json_agg inside the inner-most JOIN, instead I can call array_agg(i.images) at the same point array_agg(name) AS options is called, to get a flat list of images:
SELECT p.name, o.options, o.images
FROM products p
LEFT JOIN (
SELECT "productId", array_agg(DISTINCT name) AS options, array_agg(i.images) AS images
FROM options o
LEFT JOIN (
SELECT "optionId", i."fileName" AS images
FROM images i
) i ON i."optionId" = o.id
GROUP BY 1
) o ON o."productId" = p.id;
name | options | images
-------------+-------------------------------+------------------------------
Shampoo | {"Frizzy Hair","Hair Growth"} | {bee.png,fancy.png,soap.png}
Conditioner |

Answer 2

A different approach:
I used DISTINCT in function json_agg() (you can use array_agg() instead), so as not to repeat the name of the product Options.
SELECT
p.name,
json_agg(DISTINCT po.name) AS options,
json_agg(i."fileName") AS images
FROM products p
LEFT JOIN "productOptions" po ON p.id = po."productId"
LEFT JOIN images AS i ON po.id = i."productOptionId"
GROUP BY p.name;
Or using subqueries:
SELECT
p.name,
po.options,
poi.images
FROM products p
LEFT JOIN (SELECT productId, json_agg(name) AS options
FROM productOptions
GROUP BY productId) AS po ON p.id = po.productId
LEFT JOIN (SELECT
productId,
json_agg(fileName) AS images
FROM productOptions po
INNER JOIN images i ON i.productOptionId = po.id
GROUP BY productId) AS poi ON p.id = poi.productId;