Update json string column with proper json in Postgres SQL

Question

I have a column which type is JSON but it contains JSON strings like this:

"{\"a\":1,\"b\":2,\"c\":3}"

I want to update the values in the column with proper JSON objects without the quotes and escapes like this:

{"a":1,"b":2,"c":3}

I've tried the following statement even tough it says it does update rows, the columns are still the same.

UPDATE table SET column = to_json(column);

It seems like the to_json function doesn't work since it is a JSON string?

How can I update those values?

Answer 1

You could cast the JSON column as text, remove the unwanted quotes and escapes, and then cast the resulting text as JSON.

update tbl
set js = trim(replace(js::text, '\',''), '"')::json 

demo

Answer 2

You can use the #>> operator to extract the string and then convert it back to JSON with ::json:

UPDATE your_table
SET your_column = (your_column #>> '{}')::json;

A fully working demo:

create table your_table (
    your_column json
);

insert into your_table (your_column) values ('"{\"a\":1,\"b\":2,\"c\":3}"'::json);

select your_column, your_column #>> '{}'
from your_table ;

your_column	?column?
"{\"a\":1,\"b\":2,\"c\":3}"	{"a":1,"b":2,"c":3}

update your_table
set your_column = (your_column #>> '{}')::json;

select *
from your_table;

your_column
{"a":1,"b":2,"c":3}