Postgres 9.5 update inner json field

Question

I have a json column. The object has nested fields eg

{
  "logo": {
    "url": "https://foo.bar"
    ...
  }
  ...
}

The object has more fields, but the url field is the one that I want to update. I believe I should use something like json_set, but I'm lost regarding the json path. Can I have an example?

Answer 1

You can't do that with json only with jsonb (but you can easily cast the existing value)

With jsonb_set you need to provide the path to the object you want to change, so that would be '{logo,url}' :

The following:

with t (data) as (
  values
    ('{
        "logo": { "url": "https://foo.bar", "something" : "some value"}, 
        "other" : { "one": "two"}
      }'::jsonb
    )
)
select jsonb_set(data, '{logo,url}', to_jsonb('http://bar.foo'::text))
from t;

^{(The WITH part is only there to generate dummy data)}

returns:

jsonb_set                                                                              
---------------------------------------------------------------------------------------
{"logo": {"url": "http://bar.foo", "something": "some value"}, "other": {"one": "two"}}

As you can see, only the url attribute was replaced, everything else is left as it is.

If your column is really a json, just use your_column::jsonb so that you can use jsonb_set()