将嵌套的json插入Postgres中的列

Question

I'm writing an insert function and I have a nested dictionary that I want to insert into a column in postgres, is there a way to insert the whole json into the column? Lets say I have to insert the value of the key "val" into a column, how can I achieve that? I'm using psycopg2 library in my python code.

"val": {
  "name": {
    "mike": "2.3",
    "roy": "4.2"
     }
 }

Answer 1

Yes, you can extract nested JSON using at least Postgres 9.4 and up by casting your string to JSON and using the "Get JSON object field by key" operator:

YOUR_STRING ::CAST JSON_OPERATOR
'{"val":1}' ::JSON -> 'val'

This works in at least Postgres 9.4 and up:

INSERT INTO my_table (my_json)
    VALUES ('"val":{"name":{"mike":"2.3"}}'::JSON->'val');

Depending on your column type you may choose to cast to JSONB instead of JSON (the above will only work for TEXT and JSON).

INSERT INTO my_table (my_json) 
    VALUES ('"val":{"name":{"mike":"2.3"}}'::JSONB->'val');

See: https://www.postgresql.org/docs/9.5/static/functions-json.html