Create json with column values as object keys

问题:

I have a table defined like this:

CREATE TABLE data_table AS (
  id bigserial,
  "name" text NOT NULL,
  "value" text NOT NULL,
  CONSTRAINT data_table_pk PRIMARY KEY (id)
);

INSERT INTO data_table ("name", "value") VALUES
('key_1', 'value_1'),
('key_2', 'value_2');

I would like to get a JSON object from this table content, which will look like this:

{
  "key_1":"value_1",
  "key_2":"value_2"
}

Now I'm using the client application to parse the result set into JSON format. Is it possible to accomplish this by a postgresl query?

回答1:

If you're on 9.4 you can do the following:

$ select json_object_agg("name", "value") from data_table;
           json_object_agg
----------------------------------------------
{ "key_1" : "value_1", "key_2" : "value_2" }

回答2:

select
    format(
        '{%s}',
        string_agg(format(
            '%s:%s',
            to_json("name"),
            to_json("value")
        ), ',')
    )::json as json_object
from data_table;
          json_object              
---------------------------------------
 {"key_1":"value_1","key_2":"value_2"}