Extracting info out of lists inside a jsonb - postgresql

Question

I have a with a jsonb column called jsonb that contains data in the following format.
{
"stuff": [
{
"name": "foo",
"percent": "90.0000"
},
{
"name": "bar",
"percent": "10.0000"
}
],
"countries": [
{
"name": "USA",
"value": "30"
},
{
"name": "Canada",
"value": "25"
},
{
"name": "Mexico",
"value": "20"
},
{
"name": "Ecuador",
"value": "10"
}
]
}
I am having a lot of trouble working with this data. Specifically what I want to do is find all the different values "name" can have in "stuff" as well as in "countries", kind of like a SELECT distinct.
But my problem is that I can't seem to extract anything useful from this jsonb. My approach so far was to do
SELECT jsonb->>'stuff' FROM table, but this only gave me a column of type text which contained [{"name": "foo","percent": "90.0000"},{"name": "bar","percent": "10.0000"}].
But since this is text I can't really do anything with it. I also tried SELECT jsonb_array_elements_text(jsonb) FROM table but that returned the following Error:
ERROR: cannot extract elements from an object
SQL state: 22023
Any help with working with this format of data is greatly appreciated!

Answer 1

You need to unnest each array separately and then create a union on the result of those two steps:
select c.x ->> 'name'
from the_table
cross join lateral jsonb_array_elements(json_column -> 'countries') as c(x)
union
select s.x ->> 'name'
from the_table
cross join lateral jsonb_array_elements(json_column -> 'stuff') as s(x);
Online example: https://rextester.com/ZEOIXF91294