According to Postgres documentation:
to_jsonb(anyelemnt)
Returns the value as json or jsonb. Arrays and composites are
converted (recursively) to arrays and objects; otherwise, if there is
a cast from the type to json, the cast function will be used to
perform the conversion; otherwise, a scalar value is produced. For any
scalar type other than a number, a Boolean, or a null value, the text
representation will be used, in such a fashion that it is a valid json
or jsonb value.
IMHO you are providing a JSON formatted string, then you should use the first method.
to_json('Fred said "Hi."'::text) --> "Fred said \"Hi.\""
If you try to get an array of element using to_json(text) you’ll get the next error:
select *
from jsonb_array_elements_text(to_jsonb('[{"field":15,"operator":0,"value":"1"},{"field":15,"operator":0,"value":"2"},55]'::text));
cannot extract elements from a scalar
But if you previously cast it to json:
select *
from jsonb_array_elements_text(to_jsonb('[{"field":15,"operator":0,"value":"1"},{"field":15,"operator":0,"value":"2"},55]'::json));
+--------------------------------------------+
| value |
+--------------------------------------------+
| {"field": 15, "value": "1", "operator": 0} |
+--------------------------------------------+
| {"field": 15, "value": "2", "operator": 0} |
+--------------------------------------------+
| 55 |
+--------------------------------------------+