Creating table views with columns from nested value of a jsonb column - postgresql

Question

I have a jsonb column in one of the tables that has the following structure:
{
"3424": {
"status": "pending",
"remarks": "sample here"
},
"6436": {
"status": "new",
"remarks": "sample here"
},,
"9768": {
"status": "cancelled",
"remarks": null,
"by": "customer"
}
}
I am trying to create a view that will put the statuses in individual columns and the key will be their value:
pending | new | cancelled | accepted | id | transaction
3424 | 6436 | 9768 | null | 1 | testing
The problem is the key is dynamic (numeric and corresponds to some id) so I cannot pinpoint the exact key to use the functions/operations stated here: https://www.postgresql.org/docs/9.5/functions-json.html
I've read about json_path_query and was able to extract the statuses here without the need to know the key but I cannot combine it with the integer key yet.
select mt.id, mt.transaction, hstatus from mytable mt
cross join lateral jsonb_path_query(mt.hist, '$.**.status') hstatus
where mt.id = <id>
but this returns the statuses as rows for now. I'm pretty noob with (postgre)sql so I've only gotten this far.

Answer 1

You can indeed use a PATH query. Unfortunately it's not possible to access the "parent" inside a jsonpath in Postgres. But you can workaround that, by expanding the whole value to a list of key/values so that id value you have, can be accessed through .key
select jsonb_path_query_first(the_column, '$.keyvalue() ? (#.value.status == "pending").key') #>> '{}' as pending,
jsonb_path_query_first(the_column, '$.keyvalue() ? (#.value.status == "new").key') #>> '{}' as new,
jsonb_path_query_first(the_column, '$.keyvalue() ? (#.value.status == "cancelled").key') #>> '{}' as cancelled,
jsonb_path_query_first(the_column, '$.keyvalue() ? (#.value.status == "accepted").key') #>> '{}' as accepted,
id,
"transaction"
from the_table
The jsonpath function $.keyvalue() returns something like this:
{"id": 0, "key": "3424", "value": {"status": "pending", "remarks": "sample here"}}
This is then used to pick the an element through a condition on #.value.status and the accessor .key then returns the corresponding key value (e.g. 3424)
The #>> '{}' is a hack to convert the returned jsonb value into a proper text value (otherwise the result would be e.g. "3424" instead of just 3424.