We have this beautiful Postgres tree generator. Yet it kind of produces cuts of a tree not a whole tree all at once:
item_id jsonb_pretty1 {"title": "PARENT","item_id": 1,"children": {"title": "LEVEL 2","item_id": 2,"children": {"title": "LEVEL 3.2","item_id": 6 } }}1 {"title": "PARENT","item_id": 1,"children": {"title": "LEVEL 2","item_id": 2,"children": {"title": "LEVEL 3.1","item_id": 3,"children": {"title": "LEVEL 4.1","item_id": 4 } } }}1 {"title": "PARENT","item_id": 1,"children": {"title": "LEVEL 2","item_id": 2,"children": {"title": "LEVEL 3.1","item_id": 3,"children": {"title": "LEVEL 4.2","item_id": 5 } } }}I want to get a single tree object out from it with an array like this:
1 {"title": "PARENT","item_id": 1,"children": [{"title": "LEVEL 2","item_id": 2,"children": [{"title": "LEVEL 3.2","item_id": 6 }, {"title": "LEVEL 3.1","item_id": 3,"children": [{"title": "LEVEL 4.1","item_id": 4 }, {"title": "LEVEL 4.2","item_id": 5 }] }] }]}Here is the generator:
CREATE TABLE items ( item_id serial PRIMARY KEY, title text);CREATE TABLE joins ( id serial PRIMARY KEY, item_id int, child_id int);INSERT INTO items (item_id,title) VALUES (1,'PARENT'), (2,'LEVEL 2'), (3,'LEVEL 3.1'), (4,'LEVEL 4.1'), (5,'LEVEL 4.2'), (6,'LEVEL 3.2');INSERT INTO joins (item_id, child_id) VALUES (1,2), (2,3), (3,4), (3,5), (2,6);WITH RECURSIVE t(item_id, json, level) AS ( SELECT item_id, to_jsonb(items), 1 FROM items WHERE NOT EXISTS ( SELECT 2 FROM joins WHERE items.item_id = joins.item_id ) UNION ALL SELECT parent.item_id, to_jsonb(parent) || jsonb_build_object( 'children', t.json ), level + 1 FROM t JOIN joins AS j ON t.item_id = j.child_id JOIN items AS parent ON j.item_id = parent.item_id WHERE level < 7)SELECT item_id, jsonb_pretty(json)FROM tWHERE item_id = 1;How would I change such a generator to produce one single tree in Postgres 13+?
